How to Evaluate an API as a Product Manager - ProductFTW #49

Throughout my career, I have been asked to evaluate partner APIs or define API requirements for my team. As someone without a deep technical background, I have had to develop a way to determine whether an API will be easy to integrate or a complete headache.

There are plenty of product managers who do not work with APIs regularly, and if that is the case, evaluating one can feel overwhelming. You might not have access to technical resources yet or even know how to generate API keys. However, waiting for an engineering team to do the initial evaluation can be a waste of time if the API turns out to be poorly documented, missing key functionality, or fundamentally difficult to work with.

Over time, I have developed an approach to evaluating APIs at the earliest stages, before involving an engineering team. If you are a product manager who needs to assess an API without being overly technical, this is how you can do it.

1. Start with the Documentation

An API is only as good as its documentation. No matter how well it functions, if the team behind it cannot clearly communicate what their API does and how to use it, your team will struggle with integration.

When evaluating an API, I first read through the documentation as if I were a regular person. I look for clarity, completeness, and structure. If I find myself confused about how the API works just from reading the documentation, that is a huge red flag.

Here is what I check for:

• The endpoints are clearly documented. I should be able to understand what each endpoint does without needing an engineer to explain it.
• Error cases are outlined. Good APIs provide error messages that help troubleshoot issues instead of just returning generic failures.
• Example requests and responses are included. If an API does not have examples, your engineers will have to spend time testing and reverse-engineering it.
• Pagination, filtering, and sorting options are explained. If the API returns a list of results, I want to know if I can control how many I get back at a time or filter them down to what I need.
• Rate limits and usage restrictions are clear. If the API limits the number of requests that can be made in a given time frame, that needs to be documented upfront.

A well-documented API means that the team behind it cares about their product and is making it easier for developers to use. If the documentation is incomplete, vague, or nonexistent, that is an immediate sign that your engineers are going to have to spend a lot of time figuring things out on their own.

2. Evaluate Security and Authentication

Even without a technical background, there are basic security checks you can look for when reviewing an API. Security is one of those areas that, if overlooked, can lead to serious problems down the line.

Some key questions to ask:

• Does the API use OAuth, API keys, or some other form of authentication?
• How are API keys or access tokens handled? Are they encrypted? Does the documentation mention key rotation?
• Are there any IP allow listing or permission settings? Some APIs allow access only from approved IP addresses, which adds an extra layer of security.
• Does the API discuss rate limiting and thresholds? If an API allows unlimited requests, that can lead to abuse or performance issues. Good APIs define request limits.

If security and authentication are not well-documented, that is a red flag. Even if an API functions well, poor security practices can lead to compliance issues or expose your company to risk.

3. Check for Developer-Friendliness

An API should be easy to use, not just for the provider’s team but for the developers integrating it. Even if you are not the one coding, you can evaluate how developer-friendly an API is by looking at a few key factors.

A good API should:

• Have consistent endpoint naming and structure. If one request is /getUserData and another is /fetch-orders, that inconsistency makes it harder to use.
• Use standard HTTP methods properly. GET requests should be used to retrieve data, POST to create, PUT to update, and DELETE to remove records.
• Provide meaningful error messages rather than generic 400 Bad Request errors.
• Offer sandbox environments for testing so that engineers do not have to use live data just to see how the API works.

If an API lacks consistency or requires many custom workarounds, it will add unnecessary complexity to your project.

4. Test the API in Postman (Optional but Helpful)

If I have access to API keys, I like to test the API myself in Postman. While this is not required for every product manager, it is a useful way to validate whether the API works as expected.

The goal here is not to build anything complex but to confirm that:

1. The API does what the documentation says it does. If the documentation says a GET request should return a list of transactions, I check that it actually does.
2. Error handling is clear. I purposely send bad requests to see if the API provides useful error messages.
3. Authentication works smoothly. If getting a valid token or making a basic call is difficult, that is a sign that integration will not be straightforward.

You do not have to be technical to copy-paste a request into Postman and see what happens. If an API is well-documented, even a product manager should be able to make a single call successfully. If you cannot, that is a problem.

5. Consider the Support and Maintenance

Beyond the technical aspects, an API is also a product that needs ongoing support. Some questions to ask:

• How often is the API updated? If it has not changed in years, that could mean it is not actively maintained.
• Is there an API status page? If the API goes down, is there a place where you can check for updates?
• Is support responsive? Some APIs have dedicated support teams, while others rely on community forums. Knowing how you will get help if something breaks is important.

APIs that lack support can leave your team scrambling for solutions if something goes wrong. A well-maintained API should have clear versioning, deprecation policies, and a responsive support system.

Why Evaluating an API Matters

As a product manager, you do not need to be able to build an API to evaluate one effectively. By looking at documentation, security, developer experience, usability, and support, you can determine whether an API will be easy to work with or a long-term pain point.

It does not matter how powerful an API is if it fails in basic documentation or security. If it is confusing to integrate, your engineering team will spend time figuring it out instead of working on more valuable tasks.

A well-designed API should be intuitive, secure, well-documented, and easy to test. If it is not, you need to seriously question whether it is the right choice for your product. Making the wrong decision early can lead to delays, frustration, and unnecessary work—and as a product manager, avoiding those pitfalls is part of the job.

About ProductFTW

ProductFTW is a weekly newsletter about product management, with a focus on real-life experiences in startups. We want to help product leaders be successful by giving realistic approaches that aren’t for giant tech companies. We know you don’t have a full-time product designer on each team. We know your software probably hasn’t been used by millions of people worldwide–yet. We’re here to bridge the content gap from building your product and team to scaling it.