5 Common Misconceptions About OAuth
OAuth is widely used, particularly in systems that need to secure APIs, enable delegated access or implement modern access control strategies. Yet despite its growing adoption, it’s often misunderstood.
This post looks at five common misconceptions that can lead teams down the wrong path — and explains what to focus on instead to build secure and maintainable systems.
1. “OAuth Is Just Access Tokens”
It’s easy to associate OAuth with access tokens, since that’s often the most visible part of the system. However, OAuth isn’t just tokens, tokens are just a mechanism. The real value of OAuth lies in the framework — defining who gets access to what, under which conditions and externalizing those decisions from individual applications into a centralized authorization server.
OAuth helps ensure that authorization policies are consistent, centralized, and separate from business logic, allowing each service to focus on what it does best.
Another important aspect that’s often overlooked when talking about OAuth is the data itself. Authorization doesn’t happen in a vacuum — it exists to protect access to sensitive data that APIs expose. So, OAuth is not just about guarding endpoints, it’s about securing the data behind them, which in many cases is subject to regulatory and privacy controls like GDPR..
2. “OAuth Is Only for Third-Party Applications”
This idea stems from OAuth’s original purpose — enabling third-party applications to access user data on another service without sharing credentials. But that’s just one specific use case. It doesn’t reflect the full scope of what OAuth is designed to handle.
OAuth has long been used in first-party application scenarios — where the API provider, the client and the user all belong to the same organization. These scenarios are extremely common in modern software environments: securing internal APIs, enabling service-to-service communication in microservice architectures and supporting distributed cloud-native systems. In these cases, OAuth provides a consistent, scalable way to implement centralized access control, manage privileges across multiple services and enforce least privilege — all while maintaining visibility into who is doing what across the system. Even for internal systems, strong access control is essential. Internal APIs are just as vulnerable to attacks and misconfigurations as public ones. It also helps reduce complexity by separating security logic from business logic, allowing each component to focus on its core responsibility.
3. “OAuth Handles Authentication”
OAuth is not an authentication protocol. It was never designed to tell you who the user is. Its purpose is to manage authorization, i.e. to control what access is granted to which clients under which conditions. Think of it this way: OAuth tells you what a client can do — not who the user is.
Securing the login flow is important, but the heart of OAuth lies in the access token — in the scopes and claims that define what actions an API should allow. Unfortunately, many newcomers focus only on the authentication side and miss this entirely. No wonder broken authorization consistently ranks at the top of the OWASP Top 10 API Security Vulnerabilities list.
If your system needs to establish user identity, that’s where OpenID Connect (OIDC) comes in. OIDC extends OAuth by adding an ID token, which provides verifiable identity information in a standardized way. Blurring the lines between authorization and authentication often leads to fragile, insecure systems, and attackers know how to exploit those cracks.
4. “API Keys Are Easier and Just as Good”
API keys might look simpler on the surface, but they’re also inherently vulnerable. They’re typically static, lack any meaningful context and offer very limited control. In many cases, they were introduced early in an API’s lifecycle as a quick way to authenticate requests — and then never replaced as the system grew more complex.
The problem is that today’s APIs often handle sensitive and high-value data. Relying on a basic shared secret with no concept of user identity, scopes or claims is potentially dangerous.
OAuth access tokens, in contrast, are purpose-built for secure, contextual access:
- Who the user is (identity and roles)
- What they’re allowed to access (scopes and claims)
- Under what conditions (like tenant boundaries or business constraints)
This makes it possible to enforce fine-grained, auditable, and time-limited access.
5. “Let’s Just Put Everything in the Access Token”
A common pitfall is designing access tokens that are too large or too specific, stuffing them with every bit of context imaginable. This can lead to performance issues, stale data and unnecessary coupling between services.
For example, don’t include user metadata, such as full profile details or location history, inside a token. That information is better retrieved on demand.
Instead, tokens should:
- Be lightweight
- Contain stable claims
- Reflect only what’s needed for immediate authorization decisions
Use scopes to define access boundaries and leave complex or frequently updated data to be retrieved dynamically by the API when needed.
Conclusion: OAuth Is a Design Approach
OAuth isn’t a plug-and-play solution. It’s a framework for designing authorization, with flexibility to adapt to the needs of your architecture. It doesn’t belong in every situation. But where strong, flexible access control is needed — especially across APIs and distributed services — OAuth isa powerful enabler when used thoughtfully.
Our identity specialists wrote a book that debunks many myths about OAuth, helps utilize the building blocks OAuth provides and provides guidance on how to combine them with cloud-native technology to protect business assets in a secure and scalable way. Download Cloud Native Data Security with OAuth: A Scalable Zero Trust Architecture here.
