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.
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?