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Full stack developer interview questions

21 November 2023 , by Josh Nel

When scaling your team, finding the right full stack developer can be a challenge, especially if you’re looking for niche skills or roles. A poor hiring decision can lead to setbacks, low-quality code, and wasted time. Here, we look at full stack developer interview questions you can use to find the perfect technical and cultural fit for your team.

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Questions to ask when interviewing a full stack developer

Before diving into the technical details, it can be helpful to start with a few questions to assess a candidate’s approach to technical problems, their knowledge of the latest ecosystem developments, and how they might collaborate with your team. Here are a few questions you can use in your next interview:

  • Can you explain the differences between front end and back end development?
  • What programming languages and frameworks are you proficient in for both front end and back end development?
  • Can you discuss the advantages and disadvantages of using a monolithic architecture vs. a microservices architecture for web applications?
  • What is the Document Object Model (DOM), and how does it relate to front end development?
  • Describe the purpose of CSS preprocessors like SASS or LESS.
  • How do you optimise the performance of a web application's front end?
  • Explain the concept of RESTful APIs and how they are used in web development.
  • What is the purpose of middleware in back end development, and can you provide an example of its use?
  • How do you handle database migrations in a web application?
  • Discuss the differences between SQL and NoSQL databases. When would you use one over the other?
  • How do you prevent SQL injection and other common security vulnerabilities in database queries?
  • Can you explain the ACID properties in the context of database transactions?
  • Describe your experience with deploying applications to cloud platforms or containers.
  • What is continuous deployment (CD), and how does it differ from continuous integration?
  • How do you monitor the health and performance of a production web application?
  • How do you handle tight deadlines and prioritise tasks in a fast-paced development environment?
  • Can you provide an example of a challenging project or problem you worked on as part of a team and how you contributed to its resolution?
  • How do you stay updated with the latest industry trends and technologies in web development?

Full stack technical interview questions

Now that you’ve covered a few behavioural questions, you can move on to assessing a candidate’s technical ability. Here, we’ll look at some general interview questions, plus a few specific questions for full stack developers at different levels of seniority.

  • Explain the box model in CSS and how it impacts layout.
  • How do you center an element horizontally and vertically using CSS?
  • What is event delegation, and why is it useful in JavaScript?
  • Explain the concept of closures in JavaScript and provide an example.
  • Describe the differences between React and Angular in terms of architecture and use cases.
  • How does Vue.js differ from React or Angular, and when might you choose Vue.js for a project?
  • Explain the event loop in Node.js and how it enables non-blocking I/O.
  • What is middleware in Express.js, and how is it used in web applications?
  • Differentiate between SQL and NoSQL databases, and provide examples of each.
  • How would you design a database schema for a blog application with posts, comments, and users?
  • What is test-driven development (TDD), and how does it work in practice?
  • How do you write unit tests for a function that calculates the sum of an array of numbers in JavaScript?
  • Explain Cross-Site Scripting (XSS) attacks and how to prevent them in a web application.
  • What are Cross-Site Request Forgery (CSRF) attacks, and how can they be mitigated?

If you’re interviewing for junior or intermediate full stack developers, consider including a few of these questions:

  • Explain the purpose of HTML and CSS in web development.
  • How do you create a responsive design for a webpage using CSS?
  • What is a variable in JavaScript, and how do you declare one?
  • Describe the difference between 'null' and 'undefined' in JavaScript.
  • Have you worked with any front end frameworks like React, Angular, or Vue.js? If so, what are the basic concepts of the framework you're familiar with?
  • What is Node.js, and why is it commonly used in back end development?
  • How would you handle asynchronous operations in a Node.js application?
  • What is the purpose of unit testing in software development?
  • Can you describe the Arrange, Act, Assert (AAA) pattern for writing unit tests?
  • Write a basic SQL query to retrieve all records from a table named "Users."
  • What is the purpose of an index in a database, and when would you use one?
  • Explain the use cases for a document-based NoSQL database like MongoDB.
  • How would you model data for a simple social media application in a NoSQL database?

For more senior full stack developers, more advanced questions might be appropriate:

  • How do you approach building web interfaces that are accessible to all users, including those with disabilities?
  • What are CSS preprocessors, and can you describe their advantages and disadvantages?
  • Describe your experience with modern front end frameworks (e.g., React, Angular, Vue.js). Can you discuss their architecture and best practices?
  • How do you manage state in a large scale React application, and what tools or libraries do you use for state management?
  • Discuss the trade-offs between various database types (SQL, NoSQL) in the context of a complex application.
  • How would you design a database schema for a multi-tenant SaaS (Software as a Service) application with data isolation between tenants?
  • Explain the principles of versioning RESTful APIs, and how would you manage backward compatibility when introducing changes?
  • Can you describe API rate limiting and its importance in preventing abuse?
  • How do you handle branching and merging strategies in a large development team using Git?
  • Explain the advantages and use cases of Git submodules or Git subtrees.
  • How would you secure a web application against common security vulnerabilities like SQL injection, Cross-Site Scripting (XSS), and Cross-Site Request Forgery (CSRF)?
  • Describe your experience implementing OAuth 2.0 or OpenID Connect for authentication and authorisation in a web application.
  • Discuss strategies for optimising the performance of a database-driven web application with high traffic and data volume.
  • How do you leverage Content Delivery Networks (CDNs) and caching mechanisms to enhance website performance?

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