• Since the inception of computer science, the conceptual idea behind an API has always existed. The origins of the API can be traced back to the 1940s & '50s, to Computer Scientists Maurice Wilkes and David Wheeler who first published a book containing the specifications behind an API.
• Around 1960s, the term API was used to describe the interaction between a graphic program and the rest of the computer. But by the 1970s, APIs were incorporated into database management systems leading to the discovery that APIs support all types of programming.
• The Web-based APIs that are popular today, can be traced back to a company called Salesforce when they launched their web based sales automation tool in 2000. This was said to be the the first web API made.
• With the advent of the internet era in the 2000s, many companies understood the potential of the world wide web as a medium to deliver services, and as a result began transforming brick and mortar model store into virtual stores to conduct business.
• With a widespread commercial adoption, APIs are now an integral to almost all data exchanges made over the internet and is a vital element of all businesses who have a web presence.

The following are some of the tools used by API developers at various stages of development:

1. API Testing Tools

• RESTAssured - An open-source java library used by programmers for testing and validating the Restful Web Services.
• Postman - An HTTP client tool that tests HTTP requests, and tests suites.
• SoapUI - An open-source cross-platform API testing tool. It allows developers to write, run, integrate, and automate advanced API tests.

2. API Documentation Tools

• Swagger - An API testing and documentation tool which not only covers API documentation but also lets developers test the APIs right on the documentation itself.
• Insomnia - A cross-platform API testing tool that checks the reliability, performance, functionality, and security of the programming interfaces.

Below are some key points that we at Flexiple have learned through trial and error - a process of filtering through over 15,000 developers, to help you when you hire API developers.

• Years of software development experience: Be specific about the technology you’re looking for and the number of years of experience needed. A proxy to years of experience can be the number of production-level apps worked on.
• Type of products built in the past: Based on the type of product you are trying to build - social network, SAAS product, etc. - you can prioritize certain developers over others.
• Exposure to specific industries: Developers who have built products in certain industries will already know key aspects of laying the foundation for a great product and will be able to predict possible problems.
• Experience working remotely: A developer with past remote work experience is an added advantage as they would have first-hand experience of everything - right from how contracts work to streamlined communication, as well as timelines and deliverables.
• Strong communication: An essential thing to look at when hiring a freelancer is excellent communication skills. Since all the interaction happens online, a freelancer should be able to effectively communicate to ensure a streamlined execution of all work.

Now that you have made a quality JD, it can still be tricky to evaluate the skills of your applicants when you hire API developers. To help you with that, we have created a pool of questions that a good software developer should be comfortable with.

It is important to note that the ability to answer these questions doesn't imply that you have a top quality candidate. But it definitely is a big step in that direction.

To help you navigate through these questions, we’ve categorized the interview questions in 3 parts:

A. Basic concepts: Includes all basic concepts used across languages. This section will give you an understanding of how strong their programming foundation is.

B. Advanced concepts: Includes all concepts that someone with higher expertise should know.

C. DS/Algorithm questions: To test the logical capability of the candidate.

A. Basic concepts

Coming soon!

B. Advanced concepts

Coming soon!

C. Data Structure/ Algorithm

Coming soon!

As discussed, it isn't easy to find a quality freelance API developer but this guide makes the process easier for you. To offload the entire hiring process, reach out to us at Flexiple. We've designed a high-quality, 6-step screening process to find the top 1%, freelance developers. You can find the best freelance API developers here. We've already served over a hundred clients, earning great reviews for the quality of service.

Lastly, to quickly summarize the process of hiring an API developer for you:

• Note your project requirements and hire accordingly. Do not go for the lowest or the highest-paid developer.
• Don’t hire without vetting- consider asking questions right from the basics to advanced to logical questions.
• Look for companies like Flexiple that help you find the perfect fit.

That is everything you need to know to hire API developers. Happy hiring! :)