Best practices for building secure API Keys

Ramesh Lingappan
5 min readSep 30, 2018

We all know how valuable APIs are. They’re the gateway to exploring other services, integrating with them, and building great solutions faster.

You might have built or are thinking of building APIs for other developers to use. An API needs some form of authentication to provide authorised access to the data it returns.

There are several authentication standards available today such as API Keys, OAuth, JWT, etc.

In this article, we’ll look at how to correctly manage API Keys to access APIs.

So Why API Keys?

API Keys are simple to use, they’re short, static, and don’t expire unless revoked. They provide an easy way for multiple services to communicate.

If you provide an API for your clients to consume, it’s essential for you to build it in the right way.

Let’s get started, and I’ll show you how to build API Keys the right way.

API Key Generation

Since the API key itself is an identity by which to identify the application or the user, it needs to be unique, random and non-guessable. API keys that are generated must also use Alphanumeric and special characters. An example of such an API key is zaCELgL.0imfnc8mVLWwsAawjYr4Rx-Af50DDqtlx.

Secure API Key Storage

Since the API key provides direct access to data, it’s pretty much like a password that a user of a web or mobile app provides to gain access to the same data.

Think about it. The reason we need to store API keys is to make sure that the API key in the request is valid and issued by us (just like a password).

We don’t need to know the raw API key, but just need to validate that the key is correct. So instead of storing the key in plain text (bad) or encrypting it, we should store it as a hashed value within our database.

A hashed value means that even if someone gains unauthorised access to our database, no API keys are leaked and it’s all safe. The end user would send the raw API key in each API request, and we can validate it by hashing the API key in the request and compare the hashed key with the hash stored within our database…