API Validation - a guide

What is API validation – a guide

API validation is an important part of the development process and can help catch errors early on - here is a short guide.

API validation is the process of checking to see if an API meets certain requirements for how it works, how well it performs, how safe it is, and other things.

It is an important part of developing software because it helps make sure that an API meets the needs of its users and works as expected.

Validation can be done by hand or automatically, and there are a number of tools and services that can help.

Validating an API is an important part of making sure it works well.

What to validate?

By checking that an API meets expectations in terms of functionality, performance, security, and other quality attributes.

You can ask yourself these questions when validating your API:

  • Is the API able to perform the tasks it is designed to do?
  • How fast is the API? Does it respond quickly to requests?
  • Is the API secure? Is the data and connections properly encrypted?
  • Does the API comply with relevant standards and regulations?

How to validate?

API validation can be accomplished in a variety of ways, but the most common are static analysis, dynamic analysis, and fuzz testing. Static analysis is the process of manually going through an API’s code to look for security holes. Dynamic analysis is the process of running an API and watching how it works to look for security holes. Fuzz testing is the process of sending random data to an API to see how it responds in order to look for potential security vulnerabilities. API validation is an important part of the API development process. It helps make sure that an API is safe and doesn’t have any flaws that attackers could take advantage of.

There are a number of things to consider when validating an API:

  • What types of requests does the API support (e.g. GET, POST)?
  • What are the expected inputs and outputs for each request? 
  • What are the error conditions that the API should handle gracefully?
  • How does the API handle pagination or rate-limiting? 
  • Security: Is the API secure?
  • Are the data and communications between the API and its clients encrypted?

In order to validate APIs, you need some sort of specification that outlines how the API is supposed to work. This is typically referred to as an API contract.

The contract defines the expectations for how the API should work, including the input and output formats, the types of data that can be passed through the API, the available methods, and so on.

The OpenAPI Specification (OAS), which used to be called the Swagger Specification and is a standard way to describe APIs, is a format that is often used for API contracts.

OAS is a widely used and well-supported format, and so it is a good choice for defining API contracts.

Once you have an OAS file that defines your API contract, you can use it to generate test cases for your API. There are a number of tools that can be used for this purpose, but one that is particularly well-suited for OAS-based API testing is CherryBomb. CherryBomb is an open source tool that can be used to automatically generate test cases from an OAS API contract. It can be used to test APIs that are written in any programming language, and it has a number of features that make it particularly well-suited for API testing, including the ability to validate both the request and response bodies against the API contract. To use Cherrybomb, you first need to install it.

You can do this by using:

curl https://cherrybomb.blstsecurity.com/install | /bin/bash

Then run :

Cherrybomb oas -f openapi.json

In conclusion

API validation is a very important part of the development process, as it can help catch errors early on. It is also good practice to perform regular validation checks during the API lifecycle, in case any changes have been made that break the contract.

Developers can be sure that their API is safe to use and won’t cause any security problems if they validate it. Keep in mind that there are many ways a developer can validate an API, but a good start would be to have an API validation tool that is a seamless part of the SDLC CI pipeline.

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