Debugging Best Practices for Scalable and Error-Free APIs

Ask any API or app developer if they like debugging, and you’ll likely get a resounding “no.” Most will tell you they’d rather spend their time building cool stuff, not fixing bugs. However, debugging is a critical part of the development process, which most developers will have to do at some point.

If you want to learn more about debugging APIs and how to deal with code bugs more efficiently, this article is for you.

Debugging Common API-Related Errors

Debugging is the process of finding, identifying, and resolving unexpected behavior, errors, or inconsistencies due to code or program logic issues. Every API debugging situation is unique. You could have one bug or several causing the problem.

Here are some real-world examples of common API-related errors:

• Syntax error: Say you’re integrating a payment gateway API into an e-commerce platform. The API requires a header with “Authorization: Bearer <API_KEY>”, but you accidentally put “Auth: Bearer <API_KEY>” instead. This syntax error causes API calls to fail repeatedly.
• Logical error: You’ve built a real-time weather API that draws on third-party weather data. However, it returns incorrect sunrise/sunset times due to a logical error — it doesn’t account for time zone differences.
• Integration error: Your warehouse system uses a third-party shipping label API, and sometimes labels fail to print due to “invalid shipment details.” The API requires ZIP codes to follow a strict format. Upon inspection, you find some ZIP codes have invalid characters.
• Performance issues: Your e-commerce platform’s product catalog API now has response times of over two seconds during high traffic and sometimes times out. This might be due to some clients using the API excessively, causing an uneven distribution of traffic.

Now that we’ve covered common errors and issues, let’s focus on what you can do about them.

Common Debugging Challenges

Despite the straightforward-looking lifecycle, debugging can be a frustrating process. Many things can go wrong, and there’s usually plenty of “wasted effort” in the form of time spent troubleshooting the process instead of the errors themselves.

Common problems include misidentifying the root cause of a bug, introducing new bugs while fixing an existing one, encountering a tangle of “spaghetti code,” struggling to reproduce a bug consistently, and being unable to isolate the problem to a specific section of code.

Further, many debugging tools aren’t especially user-friendly. Long stack traces and error logs are time-consuming to read and easy to misunderstand. API consumers depend on useful status codes from APIs but often don’t get them

One of the biggest challenges for debugging an API is the difference between how it performs in development vs. the “real world.” It can be tough to figure out why a real-world bug is happening if it doesn’t appear in development conditions. APIs by definition involve connections to other systems and dependencies that can significantly complicate test parameters.

The best debugging tools let developers simulate production environments and data without impacting the live service(s) and, therefore, the consumer experience. A prod-like development environment allows developers to debug before and even after a test deployment. This means debugging starts from a more advantageous position. Similarly, advanced debugging tools that use AI to help interpret requirements or generate boilerplate code also give developers a leg up.

Let’s walk through the general steps and challenges of debugging an API.

The Debugging Lifecycle

These 7 steps make up a typical debugging process. They narrow down potential causes and help developers isolate bugs.

Step 1: Set Up the Environment

The first thing you need to do is set up your API debugging environment. Below is a non-exhaustive list of what the tools in your environment should enable:

• Sending HTTP requests
• Simulating API responses (mock servers)
• Inspecting API responses
• Analyzing network traffic
• Debugging code using breakpoints
• Generating client and server logging

Step 2: Identify the Problem

Before you dive in, read the API specification to understand how the API is meant to behave and function. The specification also tells you what results to expect when using the API.

Next, focus on the behavior of the API:

• Note what you expect the API to do vs. what it actually does.
• Does the issue happen intermittently or continuously?
• Is the problem client-side, server-side, or related to dependencies?
• What conditions trigger the problem, and does the API return error messages?

Once you’ve identified the issue, the next step is to reproduce it to determine its root cause and how to fix it.

Step 3: Reproduce the Issue

One of the most difficult parts of debugging is reproducing an issue. Developers sometimes encounter scenarios where a bug takes weeks or months to recreate. Challenging as it is, replicating the bug is a vital part of the debugging process.

Try to create an isolated example that consistently replicates the error. Review bug reports to see if they contain any helpful information. If you can’t reproduce the bug, add more logging and tracing to improve observability, giving you more information when the issue occurs.

Step 4: Analyze and Troubleshoot

Once you’ve recreated the bug, analyze and troubleshoot to find the root cause. The analysis stage involves steps that differ for every debugging scenario. Steps to analyze API bugs include:

• Using API development tools: These can help you analyze API requests and responses to find invalid data formats, missing parameters, or incorrect endpoints. In Blackbird, for example, our Code Run and Code Debug features allow developers to test code independently in a dedicated, prod-like dev environment. With Blackbird Code Run/Debug, you can catch and fix issues early without the hassle of engaging ops for infrastructure or procuring an environment.
• Inspecting headers: To spot potential issues related to content type, authentication, cookies, or security policies.
• Checking server logs: If you suspect the problem is server-side, look for error messages or anomalies.
• Using the browser’s built-in developer tools: These can analyze raw network traffic, helping you uncover issues like network latency or packet loss.

Now you’re ready to move on to the next step — developing and applying a fix.

Step 5: Develop and Apply Fixes

The fix depends on the underlying cause and may require many changes. To implement a fix, you might:

• Update the API’s code to fix syntax or logic.
• Change the server configuration.
• Update the infrastructure settings.
• Change the HTTP method (e.g., GET, POST, DELETE, PUT, PATCH).
• Reduce or update the caching time.

When updating code, logic, server configuration, or infrastructure settings, make sure your changes don’t introduce issues in edge cases or create new bugs.

Step 6: Test and Validate

Once you have your solution, you’ll need to test and validate it in a test environment to ensure it solves the problem. You should run various tests, including unit, load, functional, integration, and security.

Also, consider doing regression testing and running end-to-end API tests. Test the entire API workflow, from client requests to server responses. The API must behave as expected under different conditions and in a wide range of scenarios.

Step 7: Deploy and Monitor

You’ve thoroughly tested your solution, so it’s time to send it to production. Once you’ve deployed your bug fix, you should implement a monitoring tool for observability.

Look for API performance issues and keep an eye on error rates after you deploy your solution. Continuously monitor your API to ensure the bug doesn’t happen again and that new issues don’t pop up because of your changes.

Debugging in Different Contexts

We created Blackbird to make API development easier and faster, including debugging. Our platform simplifies and accelerates debugging through automated tools like API Mocking, Deployment Instances, and Debugging.

Blackbird lets you integrate its capabilities with your preferred integrated development environment (IDE), like Visual Studio and IntelliJ IDEA. Combining Blackbird with an IDE gives you a streamlined and accelerated debugging process

Blackbird also supports many programming languages (30+), including Python, PHP, Java, C#, Go and Ruby.

Now that we’ve introduced you to Blackbird, let’s examine API debugging in several contexts and consider where our platform fits in.

Frontend Debugging

When it comes to APIs, frontend debugging focuses on the client side, analyzing and fixing issues related to API consumption. It involves fixing frontend issues like:

• Syntax errors in client-side code
• Incorrectly formatted API responses
• Timeouts due to API calls taking too long
• Unexpected API error messages
• The API sending incorrect parameters

A mock API lets you debug the frontend without impacting the live version of your API or application. Blackbird Mock can quickly generate mock APIs from Open API specification files. Create mock API endpoints and mock responses to test API behaviors and how your API handles responses and requests.

If you integrate Blackbird Debug with an IDE like Visual Studio, you can debug your API or application using breakpoints. For example, if your API is part of a multi-threaded application, you can add more breakpoints after an initial one, setting them to activate only when a function from a specific part of the app is invoked.

Backend Debugging

Backend debugging focuses primarily on server-side code and server-side APIs. It involves fixing issues on the backend, such as:

• Syntax errors in server-side code
• Data processing errors
• Faulty business logic within an API
• Incorrectly configured authentication

You can use Visual Studio and Blackbird Debug to set conditional breakpoints in your server-side code files, telling the debugger to pause at specific places. These pauses let you inspect specific aspects of an application, like certain variables or the state of the application at certain execution points.

Mobile Debugging

Mobile debugging refers to finding and fixing issues with mobile applications and the APIs that power them. It also involves fixing problems with web pages displayed in mobile browsers.

Developers who work on mobile applications and APIs encounter many of the same issues as those who debug frontend and backend applications. After all, APIs work the same way whether powering a web or mobile application.

Additionally, mobile app developers often debug complex issues involving multiple variables or expressions. Sometimes, they see problems that require a closer look at an application’s state.

Visual Studio includes Watch Windows and QuickWatch, which let you watch specific variables and expressions. Watching expressions can help you better understand the state of your mobile application and debug complex issues involving multiple variables.

If you suspect an API is the source of your mobile application’s problems, you can debug it separately with Blackbird. You can also test mobile API execution with Blackbird.

Distributed Systems Debugging

Debugging distributed systems involves identifying and resolving problems within interconnected devices, computers, and platforms. APIs and microservices are key components of such distributed systems, which can experience problems from a wide range of sources, such as:

• Networks: Latency, packet loss, or disconnections
• Concurrencies: Race conditions or deadlocks
• Dependencies: A service or API failure impacting others
• Configurations: Misconfigured nodes

Debugging a distributed system requires tools like logging, distributed tracing, network tracing, metrics monitoring, and API call tracing

If you’re designing a system with API calls traversing multiple services, consider creating API mocks. API mocking lets you test dependencies early in the development process, helping you avoid debugging distributed system APIs later on.

Best Practices for Effective Debugging

We’ve covered the basics of debugging APIs. Finally, we’ll highlight some best practices to follow:

• Implement logging: Logging alerts you to critical events and tells you when something breaks. Make sure log entries include unique identifiers, timestamps, relevant context, and log levels.
• Use an API gateway: Most API gateways include features like performance monitoring, request and response logging, and traffic replay. These features let you track API metrics and make troubleshooting issues easier.
• Automate testing: Use automated API testing tools to run consistent tests, ensuring that changes haven’t introduced new bugs and fixed bugs don’t return later.
• Communicate with the team: Share your debugging insights to encourage collaboration. Working together helps you solve issues quickly and gets everyone on the same page regarding the process.
• Monitor performance: Throughout testing, monitor your API’s performance, looking at metrics such as response time, error rates, resource utilization, and request rates.
• Use breakpoints: Use these handy markers throughout the debugging process. For example, use breakpoints to understand the state of an application at a given point or to pause a long sequence of API calls

We recommend incorporating as many best practices into your API development processes as possible to find bugs efficiently.

Accelerate API Debugging with Blackbird

Blackbird helps developers streamline the entire API development process — from API design and mocking to coding and debugging. You get automated tools that may make you go from hating debugging to finding it tolerable, if not even fun. But if you use a complete API Development platform like Blackbird that includes the hosted development environment to deploy (pun intended) the most effective techniques, you’ll squash those bugs in no time!