API authentication

What is API authentication?

API authentication is the process of verifying the identity of a user who is making an API request, and it is a crucial pillar of API security. There are many types of API authentication, such as HTTP basic authentication, API key authentication, JWT, and OAuth, and each one has its own benefits, trade-offs, and ideal use cases. Nevertheless, all API authentication mechanisms share the goal of protecting sensitive data and ensuring the API is not misused.

Here, we'll discuss the primary benefits of API authentication, review some common methods of API authentication, explain the difference between API authentication and API authorization, and explore some API authentication best practices. We'll also highlight how the Postman API Platform supports healthy API authentication practices for producers and consumers alike.

What are the benefits of API authentication?

Today, an increasing number of organizations are focusing on APIs in order to unlock new features and advance business objectives. In fact, many teams have adopted the API-first development model, in which applications are conceptualized and built as a collection of services that are delivered through APIs. With this approach, teams prioritize API quality and security in order to ensure that their APIs remain highly performant and scalable—without serving as entry points for attackers. API authentication is a primary way in which APIs are secured, and it enables teams to protect sensitive data, build trust with users, and safeguard the company's reputation.

What are the most common methods of API authentication, and how do they work?

There are many API authentication mechanisms, and each one operates differently. These four methods are among the most common:

HTTP basic authentication

HTTP basic authentication is the most rudimentary way to implement API authentication. It involves sending credentials as user/password pairs in an Authorization header field, where the credentials are encoded using Base64. However, these credentials are not hashed or encrypted, which makes this authentication mechanism insecure unless it is used in conjunction with HTTPS.

API key authentication

An API key is a unique identifier that an API provider issues to registered users in order to control usage and monitor access. The API key must be sent with every request—either in the query string, as a request header, or as a cookie. Like HTTP basic authentication, API key authentication must be used with HTTPS to ensure the API key remains secure.

JWT authentication

JWT, which stands for JSON Web Token, is a compact, stateless mechanism for API authentication. When a user logs into an application, the API server creates a digitally signed and encrypted JWT that includes the user's identity. The client then includes the JWT in every subsequent request, which the server deserializes and validates. The user's data is therefore not stored on the server's side, which improves scalability.

OAuth authentication

OAuth is a token-based authentication mechanism that enables a user to grant third-party access to their account without having to share their login credentials. OAuth 2.0, which provides greater flexibility and scalability than OAuth 1.0, has become the gold standard for API authentication, and it supports extensive API integration without putting user data at risk.

What is the difference between API authentication and API authorization?

API authentication is often used alongside API authorization, but they are not the same thing. While API authentication involves verifying a user's identity, API authorization is the process of checking whether a user has the correct permissions to perform a specific task. It is often based on a user's role within an organization, which may have a predefined access level. For instance, junior-level developers may only be able to read data from certain endpoints, while engineering managers might have read and write access to every API endpoint within their team's scope.

What are some best practices for API authentication?

API authentication is critical to your application's overall security posture, so it's imperative that you adhere to the following best practices as you design and develop your API:

• Use a well-established authentication framework: Authentication is a complex process with high stakes, so it's important to use a well-established framework instead of writing your own authentication code from scratch. Protocols such as OAuth, OpenID Connect, and JWT have been thoroughly tested and are more secure than homegrown solutions.
• Choose an authentication method that is appropriate for your use case: When deciding how to authenticate users, it's important to consider the sensitivity of your data and the overall needs of your application. For example, HTTP basic authentication is easy to implement, but it has significant vulnerabilities and scalability issues that make it ill-suited for most production environments.
• Implement two-factor authentication: Two-factor authentication (2FA) requires a user to provide two forms of authentication, such as a password and a token. This approach adds an extra layer of security and makes it more difficult for attackers to gain access to the API.
• Use HTTPS: Some authentication mechanisms, such as HTTP basic authentication and API key authentication, are not secure because they do not encrypt credentials. It's therefore essential to use HTTPS to prevent eavesdropping and keep sensitive data secure.
• Monitor API access with logs: Even if you're confident in your API's authentication workflow, it's important to monitor logs that record access to your API. This practice will help you detect suspicious activity, such as a spike in failed login attempts or logins from an unusual location.

How can Postman help with API authentication?

The Postman API Platform comes equipped with many features that support healthy API authentication practices—whether you're producing an API or consuming one. With Postman, you can:

• Leverage a wide range of authentication mechanisms: Postman provides built-in support for several authentication types, including OAuth 2.0, API keys, JWT bearer tokens, and AWS signature. These authentication methods can be defined at the request, collection, or folder level, which facilitates inheritance and improves consistency.
• Receive security warnings about authentication issues: Postman API Governance can automatically warn you of authentication-related issues, such as exposed authentication data or a missing authentication scheme. The warning will also include a suggested fix, so you can resolve the issue quickly.
• Automatically surface exposed authentication tokens: The Postman Token Scanner scans your public workspaces, collections, and environments for exposed authentication tokens. It includes default support for tokens from over 30 service providers, and it can be customized to look for any other proprietary or third-party app tokens, as well.
• Refresh your OAuth 2.0 access tokens: Postman can automatically refresh OAuth 2.0 access tokens before they expire, which saves the user time by eliminating the need to repeat the entire authorization process.
• Quickly authenticate with public APIs: Postman will guide users through the authentication process for several popular APIs, including OpenAI, Notion, and Twilio. This feature streamlines the authentication process and significantly reduces your time to first call.
• Correlate API audit logs with other security data: Teams can monitor audit logs on a built-in dashboard to ensure that only legitimate users are interacting with their API. Audit logs can also be accessed with the Postman API, which allows teams to analyze these logs alongside security data from third-party SIEM tools.