API interview questions (with example answers and tips)

By Indeed Editorial Team

Published 5 July 2022

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

An API interview is a way for companies to see how a candidate thinks about problems and how they solve them. They also want to know whether or not a candidate is going to be able to work well with other developers. These questions are rather technical and can be challenging for people who haven't got any experience creating applications. In this article, we look at several API interview questions with example answers and a brief tips section.

API interview questions

Here are six common API interview questions with example answers:

1. What are the advantages of using an API?

The main reason a recruitment officer asks candidates to discuss the advantages of using an API in an interview is that they want to see how well the candidate understands what they're talking about. If they ask you to talk about things like user experience or interaction design, they seek assurance that you understand how these concepts apply when creating digital products. They want to ensure that you know what questions to both ask and answer when designing user interfaces and that you understand what it takes to create an intuitive experience for users.

Example: 'APIs have several advantages over other types of software. They're incredibly flexible. APIs can be easily modified or expanded, which allows them to grow as users' needs change. They're also scalable as they allow us to accommodate more users without increasing workloads. This is because they're designed to handle large numbers of requests at once. Another advantage is their security, as they're designed to protect sensitive information. APIs are less likely than other types of software to become compromised by malicious users as there are fewer vulnerabilities to exploit'.

2. What are the disadvantages of using an API?

An interviewer asks candidates to discuss the disadvantages of using an API in an API interview because they want to see how the candidate responds under pressure. This is important as candidates who remain composed tend to impress recruitment officers more. The question also conveys how much experience the candidate has using API. This means that it's important not to answer in a way that implies that there are no disadvantages at all.

Example: 'Although API is useful, I have since discovered that there are a few disadvantages of its use. For example, when working with an API, it's important to ensure that your code is compatible with the API. This can be a problem if you're using an older version of the API or if you haven't updated your software recently. It's also necessary to ensure that you're correctly implementing the API for it to work. If you misspell a function name or use a different structure than what's documented on the site, then your code won't work'.

3. Explain the difference between SOAP and REST web services

Asking a candidate to explain the difference between SOAP and REST web services in an API interview is a great way for employers to assess a candidate's understanding of the basics of API development. It's important that all developers understand the basics behind API development as this can help them better understand how to use APIs to build applications. This style of question is also useful for employers as it tests each candidate's verbal communication skills. It's crucial for a developer to be able to concisely convey themselves to their team when using technical terms.

Example: 'SOAP and REST are two different web service provisions. SOAP stands for Simple Object Access Protocol, which is a protocol for exchanging messages between computers. REST stands for Representational State Transfer, which is a style of software architecture that uses HTTP requests to retrieve and store data. SOAP is more complex than REST, but it has more functionality. REST web services are easier to implement than SOAP web services because they have less overhead. Mobile apps and the Internet of Things use these services'.

Related: What are verbal communication skills? (With tips)

4. How do you integrate a third-party API into an application?

An employer might ask a candidate how to integrate a third-party API into an application during an API interview to determine if the candidate has enough knowledge of and experience with integrating third-party APIs. API integration is a process that requires knowledge of how to use the API and how to integrate it into an application. If a candidate receives this question it's because an employer is expecting them to explain what steps they would take so that both they and their team can integrate the API into their application.

Example: 'The first step involved in integrating a third-party API into an application is finding out where the third-party API is being hosted. When I'm using Python or Ruby, this is simple. If I'm using JavaScript I choose to access the third-party API through AJAX calls or by passing information through HTML forms. I figure out what type of data to return and how to handle it when it arrives in my application, which often requires some trial and error. This then means that I'm able to integrate a third-party API into an application'.

Related: 10 of the most in-demand coding languages and their uses

5. Can you describe the 4 main parts of an API request?

There are many reasons why an interviewer might ask a candidate to describe the four main parts of an API request in an API interview. It's a way for employers to assess how well you understand the concept of an API and how it works as this can reveal your capability for the role. It's also a way to assess your communication skills. It requires you to speak clearly and concisely, which is important in all types of jobs. This question also shows that you've done your research on the company.

Example: 'The four main parts of an API request include the Header, which contains information about the request, including the request method, a reference to the resource requested and the HTTP version. The payload contains all of the data passed to the server, which can be anything from text, binary data or another URL. The query string comes after the URL's domain name. It can contain any number of key-value pairs (or just one) that describes what's wanted from the requested page. The fragment identifier follows the domain name but before any query string parameters'.

6. How does authentication work for an API request?

An interviewer might ask candidates this question to gauge their understanding of how authentication works for an API request. For example, when a developer requests an API, it can be challenging to determine what credentials are necessary to access that specific API. This may be because users need a username and password, or an API key. Interviewers may also ask this question because they want to know how well the candidate understands how authentication works for API requests and if they have experience with this type of situation.

Example: 'When using an API, it's necessary to provide some kind of credentials before the API lets you make requests. The API then makes sure those credentials are valid, and if they are it then authorises access to your account or other resources. In my experience authentication works differently depending on the type of API in use. This generally involves sending some kind of token in the request header along with your credentials. The token is usually a unique identifier that represents your account, so it lets them know who's making requests'.

Related: How to become a web developer (with roles and salary)

Tips for an API interview

Here are some tips for an API interview:

  • Prepare thoroughly. Ensure that you know what the company does and what its focus is before your interview. If you can work this information into any of your answers it can help you seem like the ideal fit.

  • Dress professionally and arrive early. Your first impression is important, so make sure you demonstrate your professionalism to your prospective employers as soon as you walk through the door.

  • Stay calm. If something goes wrong during the interview don't let it overwhelm you. Remain calm and move forward from any incidents as best as possible.

  • Maintain eye contact. Present a confident persona by maintaining eye contact throughout the interview. Smiling and using gestures are two other recommended actions to make a good impression.

  • Ask questions. Employers seek curious applicants that are genuinely interested in the role. At the end, take some time to ask some questions relating to the role.

Please note that none of the companies, institutions or organisations mentioned in this article are affiliated with Indeed.

Explore more articles