A Quick and Simple Guide to API Authentication Methods

Imagine you’re trying to enter a high-security library filled with valuable information. Before you can get in, the guards need to know who you are (authentication) and what you can do once you are inside (authorization).

Authentication lets the guards know if you have access to the library. Authorization helps them understand your level of access to the library, whether you’re a student or the librarian himself.

In the digital world, APIs connect different software applications like this library. To protect data and prevent attacks, APIs use authentication and authorization methods. In this article, we’ll look at the most common authentication methods. The articles will become more technical and less story-like, as I am running out of ideas☹.

Image created using Ideogram.ai

Authentication vs. Authorization: What’s the Difference?

Authentication: Proving your identity like showing your ID at the gate, lets the guards know if you have access to the library

Authorization: Determining your level of access, like deciding whether you’re a student or the librarian himself

The Most Common API Authentication Methods

1. Basic Authentication: The Simplest Method

Basic Authentication is the easiest to understand. You provide a username and password, which are encoded and sent in the request header. While this method is simple, it is not very secure because your credentials could be intercepted if not sent over HTTPS.

2. Bearer Authentication: Token-Based Access

Bearer Authentication involves using a security token, known as a bearer token. After you log in, the server gives you a token to use in the request header. This bearer token allows you to access the API resources. It’s more secure than Basic Authentication, but HTTPS should always be used to ensure safety.

3. API Keys: A Unique Identifier

API Keys can be viewed as a unique membership card. You receive a fixed key to access an API, and you must use it every time you make a request. API keys are simple and effective for some cases but can be intercepted if not handled securely.

4. OAuth 2.0: The Secure and Flexible Method

OAuth 2.0 is a more advanced and secure method that uses tokens to grant access. When you log in, you get an access token that allows you to access specific parts of the API for a limited time.

The best part about OAuth 2.0 is that it supports different flows (scenarios) depending on the situation. For example, Authorization Code is used for web and mobile apps, Implicit is used for single-page apps and Client Credentials can be used for server-to-server communication.

OAuth 2.0 provides stronger security and flexibility, making it a good choice for most situations.

5. OpenID Connect: Adding Identity Verification

OpenID Connect builds on OAuth 2.0 by adding an extra layer to verify a user’s identity. It uses an ID token that contains basic information about the user, such as their name or email. This method is perfect when you need to know exactly who the user is, and access has to be provided to only specific users.

Which one do you think is the best? Image created using Ideogram.ai

Quick Summary

1. Basic Authentication: Simple but insecure.
2. Bearer Tokens: More secure; requires HTTPS.
3. API Keys: Easy to use but can be insecure if exposed.
4. OAuth 2.0: Secure and flexible, best for most cases.
5. OpenID Connect: Adds identity verification on top of OAuth 2.0.

For the majority of situations, OAuth 2.0 or OpenID Connect offers the best security and scalability, keeping the API interactions safe and efficient.

As a product manager, understanding the basics of technology goes a long way. You will have to interact and ideate with engineers and developers daily. Knowing the basics first-hand is always suitable for making better product decisions and creating an impeccable user experience.

This blog post is part of a series — Technology for New PMs.