File: README — Documentation by YARD 0.9.37

📍 NOTE
RubyGems (the GitHub org, not the website) suffered a hostile takeover in September 2025.
Ultimately 4 maintainers were hard removed and a reason has been given for only 1 of those, while 2 others resigned in protest.
It is a complicated story which is difficult to parse quickly.
I’m adding notes like this to gems because I don’t condone theft of repositories or gems from their rightful owners.
If a similar theft happened with my repos/gems, I’d hope some would stand up for me.
Disenfranchised former-maintainers have started gem.coop.
Once available I will publish there exclusively; unless RubyCentral makes amends with the community.
The “Technology for Humans: Joel Draper” podcast episode by reinteractive is the most cogent summary I’m aware of.
See here, here and here for more info on what comes next.
What I’m doing: A (WIP) proposal for bundler/gem scopes, and a (WIP) proposal for a federated gem server.

# 🔐 OAuth 2.0 Authorization Framework

⭐️ including OAuth 2.1 draft spec & OpenID Connect (OIDC)

`if ci_badges.map(&:color).detect { it != "green"}` ☝️ let me know, as I may have missed the discord notification.

`if ci_badges.map(&:color).all? { it == "green"}` 👇️ send money so I can do more of this. FLOSS maintenance is now my full-time job.

## 🌻 Synopsis

OAuth 2.0 is the industry-standard protocol for authorization.
OAuth 2.0 focuses on client developer simplicity while providing specific authorization flows for web applications,
desktop applications, mobile phones, and living room devices.
This is a RubyGem for implementing OAuth 2.0 clients (not servers) in Ruby applications.

### Quick Examples

Convert the following `curl` command into a token request using this gem...

    curl --request POST \
      --url 'https://login.microsoftonline.com/REDMOND_REDACTED/oauth2/token' \
      --header 'content-type: application/x-www-form-urlencoded' \
      --data grant_type=client_credentials \
      --data client_id=REDMOND_CLIENT_ID \
      --data client_secret=REDMOND_CLIENT_SECRET \
      --data resource=REDMOND_RESOURCE_UUID

NOTE: In the ruby version below, certain params are passed to the `get_token` call, instead of the client creation.

    OAuth2::Client.new(
      "REDMOND_CLIENT_ID", # client_id
      "REDMOND_CLIENT_SECRET", # client_secret
      auth_scheme: :request_body, # Other modes are supported: :basic_auth, :tls_client_auth, :private_key_jwt
      token_url: "oauth2/token", # relative path, except with leading `/`, then absolute path
      site: "https://login.microsoftonline.com/REDMOND_REDACTED",
    ). # The base path for token_url when it is relative
      client_credentials. # There are many other types to choose from!
      get_token(resource: "REDMOND_RESOURCE_UUID")

NOTE: `header` - The content type specified in the `curl` is already the default!

Complete E2E single file script against mock-oauth2-server

- E2E example uses navikt/mock-oauth2-server, which was added in v2.0.11
- E2E example does not ship with the released gem, so clone the source to play with it.

    docker compose -f docker-compose-ssl.yml up -d --wait
    ruby examples/e2e.rb
    # If your machine is slow or Docker pulls are cold, increase the wait:
    E2E_WAIT_TIMEOUT=120 ruby examples/e2e.rb
    # The mock server serves HTTP on 8080; the example points to http://localhost:8080 by default.

The output should be something like this:

    ➜  ruby examples/e2e.rb
    Access token (truncated): eyJraWQiOiJkZWZhdWx0...
    userinfo status: 200
    userinfo body: {"sub" => "demo-sub", "aud" => ["demo-aud"], "nbf" => 1757816758000, "iss" => "http://localhost:8080/default", "exp" => 1757820358000, "iat" => 1757816758000, "jti" => "d63b97a7-ebe5-4dea-93e6-d542caba6104"}
    E2E complete

Make sure to shut down the mock server when you are done:

    docker compose -f docker-compose-ssl.yml down

Troubleshooting: validate connectivity to the mock server

- Check container status and port mapping:
  - `docker compose -f docker-compose-ssl.yml ps`
- From the host, try the discovery URL directly (this is what the example uses by default):
  - `curl -v http://localhost:8080/default/.well-known/openid-configuration`
  - If that fails immediately, also try: `curl -v --connect-timeout 2 http://127.0.0.1:8080/default/.well-known/openid-configuration`
- From inside the container (to distinguish container vs. host networking):
  - `docker exec -it oauth2-mock-oauth2-server-1 curl -v http://127.0.0.1:8080/default/.well-known/openid-configuration`
- Simple TCP probe from the host:
  - `nc -vz localhost 8080 # or: ruby -rsocket -e 'TCPSocket.new("localhost",8080).close; puts "tcp ok"'`
- Inspect which host port 8080 is bound to (should be 8080):
  - `docker inspect -f '{{ (index (index .NetworkSettings.Ports "8080/tcp") 0).HostPort }}' oauth2-mock-oauth2-server-1`
- Look at server logs for readiness/errors:
  - `docker logs -n 200 oauth2-mock-oauth2-server-1`
- On Linux, ensure nothing else is bound to 8080 and that firewall/SELinux aren’t blocking:
  - `ss -ltnp | grep :8080`

Notes

- Discovery URL pattern is: `http://localhost:8080/<realm>/.well-known/openid-configuration`, where `<realm>` defaults to `default`.
- You can change these with env vars when running the example:
  - `E2E_ISSUER_BASE` (default: http://localhost:8080)
  - `E2E_REALM` (default: default)

If it seems like you are in the wrong place, you might try one of these:

- OAuth 2.0 Spec
- doorkeeper gem for OAuth 2.0 server/provider implementation.
- oauth sibling gem for OAuth 1.0a implementations in Ruby.

## 💡 Info you can shake a stick at

Tokens to Remember |
--- | ---
Works with JRuby |
Works with Truffle Ruby |
Works with MRI Ruby 3 |
Works with MRI Ruby 2 |
Support & Community |
Source |
Documentation |
Compliance |
Style |
Maintainer 🎖️ |
`...` 💖 | 🧊 🐙 🛖 🧪

### Compatibility

Compatible with MRI Ruby 2.2.0+, and concordant releases of JRuby, and TruffleRuby.

🚚 Amazing test matrix was brought to you by | 🔎 appraisal2 🔎 and the color 💚 green 💚
--- | ---
👟 Check it out! | ✨ github.com/appraisal-rb/appraisal2 ✨

### Federated DVCS

Find this repo on federated forges (Coming soon!)

Federated DVCS Repository | Status | Issues | PRs | Wiki | CI | Discussions
--- | --- | --- | --- | --- | --- | ---
🧪 ruby-oauth/oauth2 on GitLab | The Truth | 💚 | 💚 | 💚 | 🐭 Tiny Matrix | ➖
🧊 ruby-oauth/oauth2 on CodeBerg | An Ethical Mirror (Donate) | 💚 | 💚 | ➖ | ⭕️ No Matrix | ➖
🐙 ruby-oauth/oauth2 on GitHub | Another Mirror | 💚 | 💚 | 💚 | 💯 Full Matrix | 💚
🎮️ Discord Server |  | Let’s | talk | about | this | library!

### Enterprise Support

Available as part of the Tidelift Subscription.

Need enterprise-level guarantees?

The maintainers of this and thousands of other packages are working with Tidelift to deliver commercial support and maintenance for the open source packages you use to build your applications. Save time, reduce risk, and improve code health, while paying the maintainers of the exact packages you use.

- 💡Subscribe for support guarantees covering all your FLOSS dependencies
- 💡Tidelift is part of Sonar
- 💡Tidelift pays maintainers to maintain the software you depend on!
  📊`@`Pointy Haired Boss: An enterprise support subscription is “never gonna let you down”, and supports open source maintainers

Alternatively:

## ✨ Installation

Install the gem and add to the application’s Gemfile by executing:

    bundle add oauth2

If bundler is not being used to manage dependencies, install the gem by executing:

    gem install oauth2

### 🔒 Secure Installation

For Medium or High Security Installations

This gem is cryptographically signed, and has verifiable SHA-256 and SHA-512 checksums by stone_checksums. Be sure the gem you install hasn’t been tampered with by following the instructions below.

Add my public key (if you haven’t already, expires 2045-04-29) as a trusted certificate:

    gem cert --add <(curl -Ls https://raw.github.com/galtzo-floss/certs/main/pboling.pem)

You only need to do that once. Then proceed to install with:

    gem install oauth2 -P MediumSecurity

The `MediumSecurity` trust profile will verify signed gems, but allow the installation of unsigned dependencies.

This is necessary because not all of `oauth2`’s dependencies are signed, so we cannot use `HighSecurity`.

If you want to up your security game full-time:

    bundle config set --global trust-policy MediumSecurity

`MediumSecurity` instead of `HighSecurity` is necessary if not all the gems you use are signed.

NOTE: Be prepared to track down certs for signed gems and add them the same way you added mine.

## What is new for v2.0?

- Works with Ruby versions >= 2.2
- Drop support for the expired MAC Draft (all versions)
- Support IETF rfc7515 JSON Web Signature - JWS (since v2.0.12)
  - Support JWT `kid` for key discovery and management
- Support IETF rfc7523 JWT Bearer Tokens (since v2.0.0)
- Support IETF rfc7231 Relative Location in Redirect (since v2.0.0)
- Support IETF rfc6749 Don’t set oauth params when nil (since v2.0.0)
- Support IETF rfc7009 Token Revocation (since v2.0.10, updated in v2.0.13 to support revocation via URL-encoded parameters)
- Support OIDC 1.0 Private Key JWT; based on the OAuth JWT assertion specification (RFC 7523)
- Support new formats, including from jsonapi.org: `application/vdn.api+json`, `application/vnd.collection+json`, `application/hal+json`, `application/problem+json`
- Adds option to `OAuth2::Client#get_token`:
  - `:access_token_class` (`AccessToken`); user specified class to use for all calls to `get_token`
- Adds option to `OAuth2::AccessToken#initialize`:
  - `:expires_latency` (`nil`); number of seconds by which AccessToken validity will be reduced to offset latency
- By default, keys are transformed to snake case.
  - Original keys will still work as previously, in most scenarios, thanks to snaky_hash gem.
  - However, this is a breaking change if you rely on `response.parsed.to_h` to retain the original case, and the original wasn’t snake case, as the keys in the result will be snake case.
  - As of version 2.0.4 you can turn key transformation off with the `snaky: false` option.
- By default, the `:auth_scheme` is now `:basic_auth` (instead of `:request_body`)
  - Third-party strategies and gems may need to be updated if a provider was requiring client id/secret in the request body
- … A lot more

## Compatibility

Targeted ruby compatibility is non-EOL versions of Ruby, currently 3.2, 3.3, and 3.4.
Compatibility is further distinguished as “Best Effort Support” or “Incidental Support” for older versions of Ruby.
This gem will install on Ruby versions >= v2.2 for 2.x releases.
See `1-4-stable` branch for older rubies.

Ruby Engine Compatibility Policy

This gem is tested against MRI, JRuby, and Truffleruby. Each of those has varying versions that target a specific version of MRI Ruby. This gem should work in the just-listed Ruby engines according to the targeted MRI compatibility in the table below. If you would like to add support for additional engines, see gemfiles/README.md, then submit a PR to the correct maintenance branch as according to the table below.

Ruby Version Compatibility Policy

If something doesn’t work on one of these interpreters, it’s a bug.

This library may inadvertently work (or seem to work) on other Ruby implementations; however, support will only be provided for the versions listed above.

If you would like this library to support another Ruby version, you may volunteer to be a maintainer. Being a maintainer entails making sure all tests run and pass on that implementation. When something breaks on your implementation, you will be responsible for providing patches in a timely fashion. If critical issues for a particular implementation exist at the time of a major release, support for that Ruby version may be dropped.

| Ruby OAuth2 Version | Maintenance Branch | Targeted Support | Best Effort Support | Incidental Support
--- | --- | --- | --- | --- | ---
1️⃣ | 2.0.x | `main` | 3.2, 3.3, 3.4 | 2.5, 2.6, 2.7, 3.0, 3.1 | 2.2, 2.3, 2.4
2️⃣ | 1.4.x | `1-4-stable` | 3.2, 3.3, 3.4 | 2.5, 2.6, 2.7, 3.0, 3.1 | 1.9, 2.0, 2.1, 2.2, 2.3, 2.4
3️⃣ | older | N/A | Best of luck to you! | Please upgrade! |

NOTE: The 1.4 series will only receive critical security updates.
See SECURITY.md and IRP.md.

## ⚙️ Configuration

You can turn on additional warnings.

    OAuth2.configure do |config|
      # Turn on a warning like:
      #   OAuth2::AccessToken.from_hash: `hash` contained more than one 'token' key
      config.silence_extra_tokens_warning = false # default: true
      # Set to true if you want to also show warnings about no tokens
      config.silence_no_tokens_warning = false # default: true,
    end

The “extra tokens” problem comes from ambiguity in the spec about which token is the right token.
Some OAuth 2.0 standards legitimately have multiple tokens.
You may need to subclass `OAuth2::AccessToken`, or write your own custom alternative to it, and pass it in.
Specify your custom class with the `access_token_class` option.

If you only need one token, you can, as of v2.0.10,
specify the exact token name you want to extract via the `OAuth2::AccessToken` using
the `token_name` option.

You’ll likely need to do some source diving.
This gem has 100% test coverage for lines and branches, so the specs are a great place to look for ideas.
If you have time and energy, please contribute to the documentation!

## 🔧 Basic Usage

### `authorize_url` and `token_url` are on site root (Just Works!)

    require "oauth2"
    client = OAuth2::Client.new("client_id", "client_secret", site: "https://example.org")
    # => #<OAuth2::Client:0x00000001204c8288 @id="client_id", @secret="client_sec...
    client.auth_code.authorize_url(redirect_uri: "http://localhost:8080/oauth2/callback")
    # => "https://example.org/oauth/authorize?client_id=client_id&redirect_uri=http%3A%2F%2Flocalhost%3A8080%2Foauth2%2Fcallback&response_type=code"

    access = client.auth_code.get_token("authorization_code_value", redirect_uri: "http://localhost:8080/oauth2/callback", headers: {"Authorization" => "Basic some_password"})
    response = access.get("/api/resource", params: {"query_foo" => "bar"})
    response.class.name
    # => OAuth2::Response

### Relative `authorize_url` and `token_url` (Not on site root, Just Works!)

In the above example, the default Authorization URL is `oauth/authorize` and default Access Token URL is `oauth/token`, and, as they are missing a leading `/`, both are relative.

    client = OAuth2::Client.new("client_id", "client_secret", site: "https://example.org/nested/directory/on/your/server")
    # => #<OAuth2::Client:0x00000001204c8288 @id="client_id", @secret="client_sec...
    client.auth_code.authorize_url(redirect_uri: "http://localhost:8080/oauth2/callback")
    # => "https://example.org/nested/directory/on/your/server/oauth/authorize?client_id=client_id&redirect_uri=http%3A%2F%2Flocalhost%3A8080%2Foauth2%2Fcallback&response_type=code"

### Customize `authorize_url` and `token_url`

You can specify custom URLs for authorization and access token, and when using a leading `/` they will not be relative, as shown below:

    client = OAuth2::Client.new(
      "client_id",
      "client_secret",
      site: "https://example.org/nested/directory/on/your/server",
      authorize_url: "/jaunty/authorize/",
      token_url: "/stirrups/access_token",
    )
    # => #<OAuth2::Client:0x00000001204c8288 @id="client_id", @secret="client_sec...
    client.auth_code.authorize_url(redirect_uri: "http://localhost:8080/oauth2/callback")
    # => "https://example.org/jaunty/authorize/?client_id=client_id&redirect_uri=http%3A%2F%2Flocalhost%3A8080%2Foauth2%2Fcallback&response_type=code"
    client.class.name
    # => OAuth2::Client

### snake_case and indifferent access in Response#parsed

    response = access.get("/api/resource", params: {"query_foo" => "bar"})
    # Even if the actual response is CamelCase. it will be made available as snaky:
    JSON.parse(response.body)         # => {"accessToken"=>"aaaaaaaa", "additionalData"=>"additional"}
    response.parsed                   # => {"access_token"=>"aaaaaaaa", "additional_data"=>"additional"}
    response.parsed.access_token      # => "aaaaaaaa"
    response.parsed[:access_token]    # => "aaaaaaaa"
    response.parsed.additional_data   # => "additional"
    response.parsed[:additional_data] # => "additional"
    response.parsed.class.name        # => SnakyHash::StringKeyed (from snaky_hash gem)

#### Serialization

As of v2.0.11, if you need to serialize the parsed result, you can!

There are two ways to do this, globally, or discretely. The discrete way is recommended.

##### Global Serialization Config

Globally configure `SnakyHash::StringKeyed` to use the serializer. Put this in your code somewhere reasonable (like an initializer for Rails).

    SnakyHash::StringKeyed.class_eval do
      extend SnakyHash::Serializer
    end

##### Discrete Serialization Config

Discretely configure a custom Snaky Hash class to use the serializer.

    class MySnakyHash < SnakyHash::StringKeyed
      # Give this hash class `dump` and `load` abilities!
      extend SnakyHash::Serializer
    end

    # And tell your client to use the custom class in each call:
    client = OAuth2::Client.new("client_id", "client_secret", site: "https://example.org/oauth2")
    token = client.get_token({snaky_hash_klass: MySnakyHash})

##### Serialization Extensions

These extensions work regardless of whether you used the global or discrete config above.

There are a few hacks you may need in your class to support Ruby < 2.4.2 or < 2.6.
They are likely not needed if you are on a newer Ruby.
Expand the examples below, or the ruby-oauth/snaky_hash gem,
or response_spec.rb, for more ideas, especially if you need to study the hacks for older Rubies.

See Examples

    class MySnakyHash < SnakyHash::StringKeyed
      # Give this hash class `dump` and `load` abilities!
      extend SnakyHash::Serializer

      #### Serialization Extentions
      #
      # Act on the non-hash values (including the values of hashes) as they are dumped to JSON
      # In other words, this retains nested hashes, and only the deepest leaf nodes become bananas.
      # WARNING: This is a silly example!
      dump_value_extensions.add(:to_fruit) do |value|
        "banana" # => Make values "banana" on dump
      end

      # Act on the non-hash values (including the values of hashes) as they are loaded from the JSON dump
      # In other words, this retains nested hashes, and only the deepest leaf nodes become ***.
      # WARNING: This is a silly example!
      load_value_extensions.add(:to_stars) do |value|
        "***" # Turn dumped bananas into *** when they are loaded
      end

      # Act on the entire hash as it is prepared for dumping to JSON
      # WARNING: This is a silly example!
      dump_hash_extensions.add(:to_cheese) do |value|
        if value.is_a?(Hash)
          value.transform_keys do |key|
            split = key.split("_")
            first_word = split[0]
            key.sub(first_word, "cheese")
          end
        else
          value
        end
      end

      # Act on the entire hash as it is loaded from the JSON dump
      # WARNING: This is a silly example!
      load_hash_extensions.add(:to_pizza) do |value|
        if value.is_a?(Hash)
          res = klass.new
          value.keys.each_with_object(res) do |key, result|
            split = key.split("_")
            last_word = split[-1]
            new_key = key.sub(last_word, "pizza")
            result[new_key] = value[key]
          end
          res
        else
          value
        end
      end
    end

#### Prefer camelCase over snake_case? => snaky: false

    response = access.get("/api/resource", params: {"query_foo" => "bar"}, snaky: false)
    JSON.parse(response.body)         # => {"accessToken"=>"aaaaaaaa", "additionalData"=>"additional"}
    response.parsed                   # => {"accessToken"=>"aaaaaaaa", "additionalData"=>"additional"}
    response.parsed["accessToken"]    # => "aaaaaaaa"
    response.parsed["additionalData"] # => "additional"
    response.parsed.class.name        # => Hash (just, regular old Hash)

Debugging & Logging

Set an environment variable as per usual (e.g. with dotenv).

    # will log both request and response, including bodies
    ENV["OAUTH_DEBUG"] = "true"

By default, debug output will go to `$stdout`. This can be overridden when initializing your OAuth2::Client.

    require "oauth2"
    client = OAuth2::Client.new(
      "client_id",
      "client_secret",
      site: "https://example.org",
      logger: Logger.new("example.log", "weekly"),
    )

### OAuth2::Response

The `AccessToken` methods `#get`, `#post`, `#put` and `#delete` and the generic `#request`
will return an instance of the #OAuth2::Response class.

This instance contains a `#parsed` method that will parse the response body and
return a Hash-like `SnakyHash::StringKeyed` if the `Content-Type` is `application/x-www-form-urlencoded` or if
the body is a JSON object. It will return an Array if the body is a JSON
array. Otherwise, it will return the original body string.

The original response body, headers, and status can be accessed via their
respective methods.

### OAuth2::AccessToken

If you have an existing Access Token for a user, you can initialize an instance
using various class methods including the standard new, `from_hash` (if you have
a hash of the values), or `from_kvform` (if you have an
`application/x-www-form-urlencoded` encoded string of the values).

Options (since v2.0.x unless noted):

- `expires_latency` (Integer | nil): Seconds to subtract from expires_in when computing #expired? to offset latency.

- `token_name` (String | Symbol | nil): When multiple token-like fields exist in responses, select the field name to use as the access token (since v2.0.10).

- `mode` (Symbol | Proc | Hash): Controls how the token is transmitted on requests made via this AccessToken instance.

  - `:header` — Send as Authorization: Bearer header (default and preferred by OAuth 2.1 draft guidance).
  - `:query` — Send as access_token query parameter (discouraged in general, but required by some providers).
  - Verb-dependent (since v2.0.15): Provide either:
    - a `Proc` taking `|verb|` and returning `:header` or `:query`, or
    - a `Hash` with verb symbols as keys, for example `{get: :query, post: :header, delete: :header}`.

Note: Verb-dependent mode supports providers like Instagram that require query mode for `GET` and header mode for `POST`/`DELETE`

- Verb-dependent mode via `Proc` was added in v2.0.15
- Verb-dependent mode via `Hash` was added in v2.0.16

### OAuth2::Error

On 400+ status code responses, an `OAuth2::Error` will be raised. If it is a
standard OAuth2 error response, the body will be parsed and `#code` and `#description` will contain the values provided from the error and
`error_description` parameters. The `#response` property of `OAuth2::Error` will
always contain the `OAuth2::Response` instance.

If you do not want an error to be raised, you may use `:raise_errors => false`
option on initialization of the client. In this case the `OAuth2::Response`
instance will be returned as usual and on 400+ status code responses, the
Response instance will contain the `OAuth2::Error` instance.

### Authorization Grants

Note on OAuth 2.1 (draft):

- PKCE is required for all OAuth clients using the authorization code flow (especially public clients). Implement PKCE in your app when required by your provider. See RFC 7636 and RFC 8252.
- Redirect URIs must be compared using exact string matching by the Authorization Server.
- The Implicit grant (response_type=token) and the Resource Owner Password Credentials grant are omitted from OAuth 2.1; they remain here for OAuth 2.0 compatibility but should be avoided for new apps.
- Bearer tokens in the query string are omitted due to security risks; prefer Authorization header usage.
- Refresh tokens for public clients must either be sender-constrained (e.g., DPoP/MTLS) or one-time use.
- The definitions of public and confidential clients are simplified to refer only to whether the client has credentials.

References:

- OAuth 2.1 draft: https://datatracker.ietf.org/doc/html/draft-ietf-oauth-v2-1-13
- Aaron Parecki: https://aaronparecki.com/2019/12/12/21/its-time-for-oauth-2-dot-1
- FusionAuth: https://fusionauth.io/blog/2020/04/15/whats-new-in-oauth-2-1
- Okta: https://developer.okta.com/blog/2019/12/13/oauth-2-1-how-many-rfcs
- Video: https://www.youtube.com/watch?v=g_aVPdwBTfw
- Differences overview: https://fusionauth.io/learn/expert-advice/oauth/differences-between-oauth-2-oauth-2-1/

Currently, the Authorization Code, Implicit, Resource Owner Password Credentials, Client Credentials, and Assertion
authentication grant types have helper strategy classes that simplify client
use. They are available via the `#auth_code`,
`#implicit`,
`#password`,
`#client_credentials`, and
`#assertion` methods respectively.

These aren’t full examples, but demonstrative of the differences between usage for each strategy.

    auth_url = client.auth_code.authorize_url(redirect_uri: "http://localhost:8080/oauth/callback")
    access = client.auth_code.get_token("code_value", redirect_uri: "http://localhost:8080/oauth/callback")

    auth_url = client.implicit.authorize_url(redirect_uri: "http://localhost:8080/oauth/callback")
    # get the token params in the callback and
    access = OAuth2::AccessToken.from_kvform(client, query_string)

    access = client.password.get_token("username", "password")

    access = client.client_credentials.get_token

    # Client Assertion Strategy
    # see: https://tools.ietf.org/html/rfc7523
    claimset = {
      iss: "http://localhost:3001",
      aud: "http://localhost:8080/oauth2/token",
      sub: "me@example.com",
      exp: Time.now.utc.to_i + 3600,
    }
    assertion_params = [claimset, "HS256", "secret_key"]
    access = client.assertion.get_token(assertion_params)

    # The `access` (i.e. access token) is then used like so:
    access.token # actual access_token string, if you need it somewhere
    access.get("/api/stuff") # making api calls with access token

If you want to specify additional headers to be sent out with the
request, add a ‘headers’ hash under ‘params’:

    access = client.auth_code.get_token("code_value", redirect_uri: "http://localhost:8080/oauth/callback", headers: {"Some" => "Header"})

You can always use the `#request` method on the `OAuth2::Client` instance to make
requests for tokens for any Authentication grant type.

## 📘 Comprehensive Usage

### Common Flows (end-to-end)

- Authorization Code (server-side web app):

    require "oauth2"
    client = OAuth2::Client.new(
      ENV["CLIENT_ID"],
      ENV["CLIENT_SECRET"],
      site: "https://provider.example.com",
      redirect_uri: "https://my.app.example.com/oauth/callback",
    )

    # Step 1: redirect user to consent
    state = SecureRandom.hex(16)
    auth_url = client.auth_code.authorize_url(scope: "openid profile email", state: state)
    # redirect_to auth_url

    # Step 2: handle the callback
    # params[:code], params[:state]
    raise "state mismatch" unless params[:state] == state
    access = client.auth_code.get_token(params[:code])

    # Step 3: call APIs
    profile = access.get("/api/v1/me").parsed

- Client Credentials (machine-to-machine):

    client = OAuth2::Client.new(ENV["CLIENT_ID"], ENV["CLIENT_SECRET"], site: "https://provider.example.com")
    access = client.client_credentials.get_token(audience: "https://api.example.com")
    resp = access.get("/v1/things")

- Resource Owner Password (legacy; avoid when possible):

    access = client.password.get_token("jdoe", "s3cret", scope: "read")

#### Examples

JHipster UAA (Spring Cloud) password grant example (legacy; avoid when possible)

    # This converts a Postman/Net::HTTP multipart token request to oauth2 gem usage.
    # JHipster UAA typically exposes the token endpoint at /uaa/oauth/token.
    # The original snippet included:
    # - Basic Authorization header for the client (web_app:changeit)
    # - X-XSRF-TOKEN header from a cookie (some deployments require it)
    # - grant_type=password with username/password and client_id
    # Using oauth2 gem, you don't need to build multipart bodies; the gem sends
    # application/x-www-form-urlencoded as required by RFC 6749.

    require "oauth2"

    client = OAuth2::Client.new(
      "web_app",            # client_id
      "changeit",           # client_secret
      site: "http://localhost:8080/uaa",
      token_url: "/oauth/token",      # absolute under site (or "oauth/token" relative)
      auth_scheme: :basic_auth,         # sends HTTP Basic Authorization header
    )

    # If your UAA requires an XSRF header for the token call, provide it as a header.
    # Often this is not required for token endpoints, but if your gateway enforces it,
    # obtain the value from the XSRF-TOKEN cookie and pass it here.
    xsrf_token = ENV["X_XSRF_TOKEN"] # e.g., pulled from a prior set-cookie value

    access = client.password.get_token(
      "admin",                 # username
      "admin",                 # password
      headers: xsrf_token ? {"X-XSRF-TOKEN" => xsrf_token} : {},
      # JHipster commonly also accepts/needs the client_id in the body; include if required:
      # client_id: "web_app",
    )

    puts access.token
    puts access.to_hash # full token response

Notes:

- Resource Owner Password Credentials (ROPC) is deprecated in OAuth 2.1 and discouraged. Prefer Authorization Code + PKCE.
- If your deployment strictly demands the X-XSRF-TOKEN header, first fetch it from an endpoint that sets the XSRF-TOKEN cookie (often “/” or a login page) and pass it to headers.
- For Basic auth, auth_scheme: :basic_auth handles the Authorization header; you do not need to base64-encode manually.

### Instagram API (verb‑dependent token mode)

Providers like Instagram require the access token to be sent differently depending on the HTTP verb:

- GET requests: token must be in the query string (?access_token=…)
- POST/DELETE requests: token must be in the Authorization header (Bearer …)

Since v2.0.15, you can configure an AccessToken with a verb‑dependent mode. The gem will choose how to send the token based on the request method.

Example: exchanging and refreshing long‑lived Instagram tokens, and making API calls

    require "oauth2"

    # NOTE: Users authenticate via Facebook Login to obtain a short‑lived user token (not shown here).
    # See Facebook Login docs for obtaining the initial short‑lived token.

    client = OAuth2::Client.new(nil, nil, site: "https://graph.instagram.com")

    # Start with a short‑lived token you already obtained via Facebook Login
    short_lived = OAuth2::AccessToken.new(
      client,
      ENV["IG_SHORT_LIVED_TOKEN"],
      # Key part: verb‑dependent mode
      mode: {get: :query, post: :header, delete: :header},
    )

    # 1) Exchange for a long‑lived token (Instagram requires GET with access_token in query)
    #    Endpoint: GET https://graph.instagram.com/access_token
    #    Params: grant_type=ig_exchange_token, client_secret=APP_SECRET
    exchange = short_lived.get(
      "/access_token",
      params: {
        grant_type: "ig_exchange_token",
        client_secret: ENV["IG_APP_SECRET"],
        # access_token param will be added automatically by the AccessToken (mode => :query for GET)
      },
    )
    long_lived_token_value = exchange.parsed["access_token"]

    long_lived = OAuth2::AccessToken.new(
      client,
      long_lived_token_value,
      mode: {get: :query, post: :header, delete: :header},
    )

    # 2) Refresh the long‑lived token (Instagram uses GET with token in query)
    #    Endpoint: GET https://graph.instagram.com/refresh_access_token
    refresh_resp = long_lived.get(
      "/refresh_access_token",
      params: {grant_type: "ig_refresh_token"},
    )
    long_lived = OAuth2::AccessToken.new(
      client,
      refresh_resp.parsed["access_token"],
      mode: {get: :query, post: :header, delete: :header},
    )

    # 3) Typical API GET request (token in query automatically)
    me = long_lived.get("/me", params: {fields: "id,username"}).parsed

    # 4) Example POST (token sent via Bearer header automatically)
    # Note: Replace the path/params with a real Instagram Graph API POST you need,
    # such as publishing media via the Graph API endpoints.
    # long_lived.post("/me/media", body: {image_url: "https://...", caption: "hello"})

Tips:

- Avoid query‑string bearer tokens unless required by your provider. Instagram explicitly requires it for `GET` requests.
- If you need a custom rule, you can pass a `Proc` for `mode`, e.g. `mode: ->(verb) { verb == :get ? :query : :header }`.

### Refresh Tokens

When the server issues a refresh_token, you can refresh manually or implement an auto-refresh wrapper.

- Manual refresh:

    if access.expired?
      access = access.refresh
    end

- Auto-refresh wrapper pattern:

    class AutoRefreshingToken
      def initialize(token_provider, store: nil)
        @token = token_provider
        @store = store # e.g., something that responds to read/write for token data
      end

      def with(&blk)
        tok = ensure_fresh!
        blk ? blk.call(tok) : tok
      rescue OAuth2::Error => e
        # If a 401 suggests token invalidation, try one refresh and retry once
        if e.response && e.response.status == 401 && @token.refresh_token
          @token = @token.refresh
          @store.write(@token.to_hash) if @store
          retry
        end
        raise
      end

    private

      def ensure_fresh!
        if @token.expired? && @token.refresh_token
          @token = @token.refresh
          @store.write(@token.to_hash) if @store
        end
        @token
      end
    end

    # usage
    keeper = AutoRefreshingToken.new(access)
    keeper.with { |tok| tok.get("/v1/protected") }

Persist the token across processes using `AccessToken#to_hash` and `AccessToken.from_hash(client, hash)`.

### Token Revocation (RFC 7009)

You can revoke either the access token or the refresh token.

    # Revoke the current access token
    access.revoke(token_type_hint: :access_token)

    # Or explicitly revoke the refresh token (often also invalidates associated access tokens)
    access.revoke(token_type_hint: :refresh_token)

### Client Configuration Tips

#### Mutual TLS (mTLS) client authentication

Some providers require OAuth requests (including the token request and subsequent API calls) to be sender‑constrained using mutual TLS (mTLS). With this gem, you enable mTLS by providing a client certificate/private key to Faraday via connection_opts.ssl and, if your provider requires it for client authentication, selecting the tls_client_auth auth_scheme.

Example using PEM files (certificate and key):

    require "oauth2"
    require "openssl"

    client = OAuth2::Client.new(
      ENV.fetch("CLIENT_ID"),
      ENV.fetch("CLIENT_SECRET"),
      site: "https://example.com",
      authorize_url: "/oauth/authorize/",
      token_url: "/oauth/token/",
      auth_scheme: :tls_client_auth, # if your AS requires mTLS-based client authentication
      connection_opts: {
        ssl: {
          client_cert: OpenSSL::X509::Certificate.new(File.read("localhost.pem")),
          client_key: OpenSSL::PKey::RSA.new(File.read("localhost-key.pem")),
          # Optional extras, uncomment as needed:
          # ca_file: "/path/to/ca-bundle.pem",   # custom CA(s)
          # verify: true                           # enable server cert verification (recommended)
        },
      },
    )

    # Example token request (any grant type can be used). The mTLS handshake
    # will occur automatically on HTTPS calls using the configured cert/key.
    access = client.client_credentials.get_token

    # Subsequent resource requests will also use mTLS on HTTPS endpoints of `site`:
    resp = access.get("/v1/protected")

Notes:

- Files must contain the appropriate PEMs. The private key may be encrypted; if so, pass a password to `OpenSSL::PKey::RSA.new(File.read(path), ENV["KEY_PASSWORD"])`.
- If your certificate and key are in a PKCS#12/PFX bundle, you can load them like:
  - `p12 = OpenSSL::PKCS12.new(File.read("client.p12"), ENV["P12_PASSWORD"])`
  - `client_cert = p12.certificate; client_key = p12.key`
- Server trust:
  - If your environment does not have system CAs, specify `ca_file` or `ca_path` inside the `ssl:` hash.
  - Keep `verify: true` in production. Set `verify: false` only for local testing.
- Faraday adapter: Any adapter that supports Ruby’s OpenSSL should work. `net_http` (default) and `net_http_persistent` are common choices.
- Scope of mTLS: The SSL client cert is applied to any HTTPS request made by this client (token and resource requests) to the configured site base URL (and absolute URLs you call with the same client).
- OIDC tie-in: Some OPs require tls_client_auth at the token endpoint per OIDC/OAuth specifications. That is enabled via `auth_scheme: :tls_client_auth` as shown above.

#### Authentication schemes for the token request

    OAuth2::Client.new(
      id,
      secret,
      site: "https://provider.example.com",
      auth_scheme: :basic_auth, # default. Alternatives: :request_body, :tls_client_auth, :private_key_jwt
    )

#### Faraday connection, timeouts, proxy, custom adapter/middleware:

    client = OAuth2::Client.new(
      id,
      secret,
      site: "https://provider.example.com",
      connection_opts: {
        request: {open_timeout: 5, timeout: 15},
        proxy: ENV["HTTPS_PROXY"],
        ssl: {verify: true},
      },
    ) do |faraday|
      faraday.request(:url_encoded)
      # faraday.response :logger, Logger.new($stdout) # see OAUTH_DEBUG below
      faraday.adapter(:net_http_persistent) # or any Faraday adapter you need
    end

##### Using flat query params (`Faraday::FlatParamsEncoder`)

Some APIs expect repeated key parameters to be sent as flat params rather than arrays. Faraday provides `FlatParamsEncoder` for this purpose. You can configure the oauth2 client to use it when building requests.

    require "faraday"

    client = OAuth2::Client.new(
      id,
      secret,
      site: "https://api.example.com",
      # Pass Faraday connection options to make FlatParamsEncoder the default
      connection_opts: {
        request: {params_encoder: Faraday::FlatParamsEncoder},
      },
    ) do |faraday|
      faraday.request(:url_encoded)
      faraday.adapter(:net_http)
    end

    access = client.client_credentials.get_token

    # Example of a GET with two flat filter params (not an array):
    # Results in: ?filter=order.clientCreatedTime%3E1445006997000&filter=order.clientCreatedTime%3C1445611797000
    resp = access.get(
      "/v1/orders",
      params: {
        # Provide the values as an array; FlatParamsEncoder expands them as repeated keys
        filter: [
          "order.clientCreatedTime>1445006997000",
          "order.clientCreatedTime<1445611797000",
        ],
      },
    )

If you instead need to build a raw Faraday connection yourself, the equivalent configuration is:

    conn = Faraday.new("https://api.example.com", request: {params_encoder: Faraday::FlatParamsEncoder})

#### Redirection

The library follows up to `max_redirects` (default 5).
You can override per-client via `options[:max_redirects]`.

### Handling Responses and Errors

- Parsing:

    resp = access.get("/v1/thing")
    resp.status     # Integer
    resp.headers    # Hash
    resp.body       # String
    resp.parsed     # SnakyHash::StringKeyed or Array when JSON array

- Error handling:

    begin
      access.get("/v1/forbidden")
    rescue OAuth2::Error => e
      e.code         # OAuth2 error code (when present)
      e.description  # OAuth2 error description (when present)
      e.response     # OAuth2::Response (full access to status/headers/body)
    end

- Disable raising on 4xx/5xx to inspect the response yourself:

    client = OAuth2::Client.new(id, secret, site: site, raise_errors: false)
    res = client.request(:get, "/v1/maybe-errors")
    if res.status == 429
      sleep res.headers["retry-after"].to_i
    end

### Making Raw Token Requests

If a provider requires non-standard parameters or headers, you can call `client.get_token` directly:

    access = client.get_token({
      grant_type: "client_credentials",
      audience: "https://api.example.com",
      headers: {"X-Custom" => "value"},
      parse: :json, # override parsing
    })

### OpenID Connect (OIDC) Notes

- If the token response includes an `id_token` (a JWT), this gem surfaces it but does not validate the signature. Use a JWT library and your provider’s JWKs to verify it.
- For private_key_jwt client authentication, provide `auth_scheme: :private_key_jwt` and ensure your key configuration matches the provider requirements.
- See OIDC.md for a more complete OIDC overview, example, and links to the relevant specifications.

### Debugging

- Set environment variable `OAUTH_DEBUG=true` to enable verbose Faraday logging (uses the client-provided logger).
- To mirror a working curl request, ensure you set the same auth scheme, params, and content type. The Quick Example at the top shows a curl-to-ruby translation.

## 🦷 FLOSS Funding

While ruby-oauth tools are free software and will always be, the project would benefit immensely from some funding.
Raising a monthly budget of… “dollars” would make the project more sustainable.

We welcome both individual and corporate sponsors! We also offer a
wide array of funding channels to account for your preferences
(although currently Open Collective is our preferred funding platform).

If you’re working in a company that’s making significant use of ruby-oauth tools we’d
appreciate it if you suggest to your company to become a ruby-oauth sponsor.

You can support the development of ruby-oauth tools via
GitHub Sponsors,
Liberapay,
PayPal,
Open Collective
and Tidelift.

📍 NOTE
If doing a sponsorship in the form of donation is problematic for your company from an accounting standpoint, we’d recommend the use of Tidelift, where you can get a support-like subscription instead.

### Open Collective for Individuals

Support us with a monthly donation and help us continue our activities. [Become a backer]

NOTE: kettle-readme-backers updates this list every day, automatically.

No backers yet. Be the first!

### Open Collective for Organizations

Become a sponsor and get your logo on our README on GitHub with a link to your site. [Become a sponsor]

NOTE: kettle-readme-backers updates this list every day, automatically.

No sponsors yet. Be the first!

### Another way to support open-source

I’m driven by a passion to foster a thriving open-source community – a space where people can tackle complex problems, no matter how small. Revitalizing libraries that have fallen into disrepair, and building new libraries focused on solving real-world challenges, are my passions. I was recently affected by layoffs, and the tech jobs market is unwelcoming. I’m reaching out here because your support would significantly aid my efforts to provide for my family, and my farm (11 🐔 chickens, 2 🐶 dogs, 3 🐰 rabbits, 8 🐈‍ cats).

If you work at a company that uses my work, please encourage them to support me as a corporate sponsor. My work on gems you use might show up in `bundle fund`.

I’m developing a new library, floss_funding, designed to empower open-source developers like myself to get paid for the work we do, in a sustainable way. Please give it a look.

Floss-Funding.dev: 👉️ No network calls. 👉️ No tracking. 👉️ No oversight. 👉️ Minimal crypto hashing. 💡 Easily disabled nags

## 🔐 Security

To report a security vulnerability, please use the Tidelift security contact.
Tidelift will coordinate the fix and disclosure.

For more see SECURITY.md, THREAT_MODEL.md, and IRP.md.

## 🤝 Contributing

If you need some ideas of where to help, you could work on adding more code coverage,
or if it is already 💯 (see below) check reek, issues, or PRs,
or use the gem and think about how it could be better.

We so if you make changes, remember to update it.

See CONTRIBUTING.md for more detailed instructions.

### 🚀 Release Instructions

See CONTRIBUTING.md.

### Code Coverage

### 🪇 Code of Conduct

Everyone interacting with this project’s codebases, issue trackers,
chat rooms and mailing lists agrees to follow the .

## 🌈 Contributors

Made with contributors-img.

Also see GitLab Contributors: https://gitlab.com/ruby-oauth/oauth2/-/graphs/main

⭐️ Star History

## 📌 Versioning

This Library adheres to .
Violations of this scheme should be reported as bugs.
Specifically, if a minor or patch version is released that breaks backward compatibility,
a new version should be immediately released that restores compatibility.
Breaking changes to the public API will only be introduced with new major versions.

> dropping support for a platform is both obviously and objectively a breaking change
> —Jordan Harband (@ljharb, maintainer of SemVer) in SemVer issue 716

I understand that policy doesn’t work universally (“exceptions to every rule!”),
but it is the policy here.
As such, in many cases it is good to specify a dependency on this library using
the Pessimistic Version Constraint with two digits of precision.

For example:

    spec.add_dependency("oauth2", "~> 2.0")

📌 Is "Platform Support" part of the public API? More details inside.

SemVer should, IMO, but doesn’t explicitly, say that dropping support for specific Platforms is a breaking change to an API, and for that reason the bike shedding is endless.

To get a better understanding of how SemVer is intended to work over a project’s lifetime, read this article from the creator of SemVer:

- “Major Version Numbers are Not Sacred”

See CHANGELOG.md for a list of releases.

## 📄 License

The gem is available as open source under the terms of
the MIT License .
See LICENSE.txt for the official Copyright Notice.

### © Copyright

- Copyright (c) 2017 – 2025 Peter H. Boling, of Galtzo.com , and oauth2 contributors.
- Copyright (c) 2011 - 2013 Michael Bleigh and Intridea, Inc.

## 🤑 A request for help

Maintainers have teeth and need to pay their dentists.
After getting laid off in an RIF in March, and encountering difficulty finding a new one,
I began spending most of my time building open source tools.
I’m hoping to be able to pay for my kids’ health insurance this month,
so if you value the work I am doing, I need your support.
Please consider sponsoring me or the project.

To join the community or get help 👇️ Join the Discord.

To say “thanks!” ☝️ Join the Discord or 👇️ send money.

💌 💌 💌

### Please give the project a star ⭐ ♥.

Thanks for RTFM. ☺️

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