OAuth and JWT Explained: Their Roles in Access and Identity Management

Read full article from Descope here:  https://www.descope.com/blog/post/jwt-vs-oauth/?utm_source=nhimg

When building secure web and mobile applications, authentication and authorization are two pillars you cannot ignore. Developers often encounter JSON Web Tokens (JWT) and Open Authorization (OAuth), which are sometimes mentioned together—but serve very different purposes.

• JWT is a token format for securely transmitting claims.
• OAuth is a framework for granting access without sharing passwords.

This guide explains their key differences, common use cases, and how they can work together to secure modern applications.

JWT vs OAuth at a Glance

What is JWT?

JSON Web Tokens (JWTs) are a compact, URL-safe way to transmit claims between parties using JSON. They are self-contained, meaning they carry all the necessary information for authentication and authorization, reducing the need for repeated database lookups.

A JWT consists of three parts:

1. Header: Token type and signing algorithm (e.g., HS256, RS256)
2. Payload: Claims such as iss (issuer), sub (subject), exp (expiration), and optional custom claims like user roles
3. Signature: Ensures token integrity and authenticity

Common uses:

• ID tokens in OpenID Connect (OIDC)
• Access tokens for OAuth-protected APIs
• Stateless authentication in web and mobile apps

Considerations:

• JWTs are harder to revoke before expiration
• Tokens can become large if overloaded with claims
• Proper key management and claim validation are critical

What is OAuth?

OAuth is a delegated authorization framework that allows applications to access a user’s resources without sharing passwords. Instead, users grant permission, and the application receives access tokens, which can be JWTs or opaque tokens.

Key roles in OAuth:

• Resource owner: The user granting access
• Client: The application requesting access
• Resource server: The server hosting the data or API
• Authorization server: Authenticates the user and issues tokens

Common OAuth flows:

• Authorization Code with PKCE: Recommended for browsers and mobile apps
• Client Credentials: Server-to-server access
• Device Code: For input-constrained devices
• Implicit: Deprecated in favor of Authorization Code with PKCE

Example: A project management app accessing a user’s Google Drive without requesting their password. OAuth handles token issuance and access control securely.

JWT vs OAuth: Key Differences

• Purpose: JWT structures and signs claims; OAuth defines how access is delegated and tokens are used.
• Use case: JWTs transmit identity/permissions; OAuth grants controlled API access without passwords.
• Relationship: OAuth can issue JWTs, but JWTs can exist outside OAuth.
• State management: JWTs are stateless; OAuth tokens can be stateless (JWT) or stateful (opaque).
• Revocation: JWTs are harder to revoke mid-lifecycle; OAuth can revoke opaque tokens in real time.

In short: JWT = the envelope; OAuth = the process for securely granting and managing access.

Can You Use JWT and OAuth Together?

Yes. They complement each other:

• OAuth handles secure delegated access
• JWT provides compact, self-contained tokens

For example, OpenID Connect (OIDC) uses OAuth 2.0 flows and issues JWT ID tokens for authentication and access.

Best practices:

• Use short-lived JWTs with rotation
• Validate signatures and claims
• Enforce secure OAuth flows with proper redirect URIs, scopes, and storage

When to Use JWT, OAuth, or Both