> For the complete documentation index, see [llms.txt](https://docs.serverlessapigateway.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.serverlessapigateway.com/glossary/o/oauth.md). # OAuth OAuth (Open Authorization) is an open standard protocol for token-based authorization on the internet. It allows users to grant third-party applications limited access to their resources on another service without sharing their credentials. OAuth 2.0 is the current version and is widely adopted across the industry. OAuth 2.0 defines several authorization flows (called grant types) for different scenarios: Authorization Code for server-side applications, Implicit for browser-based apps (now deprecated in favor of PKCE), Client Credentials for machine-to-machine communication, and Device Code for devices with limited input capabilities. Each flow results in the issuance of an access token that the client uses to authenticate API requests. API gateways commonly validate OAuth tokens as part of their authentication pipeline. The gateway can verify token signatures, check expiration, validate scopes, and reject unauthorized requests before they reach backend services. This centralizes token validation logic and ensures consistent security enforcement across all API endpoints. Integration with OAuth providers like Auth0, Okta, or Supabase is a common API gateway feature. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.serverlessapigateway.com/glossary/o/oauth.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.