Junior Software Engineer Interview Questions

1.1Data types, variables, control flow, and functions - the building blocks of any language

1.2Object-oriented programming - classes, objects, inheritance, and encapsulation

1.3Data structures - arrays, linked lists, stacks, queues, trees, and hash maps

1.4Algorithms - sorting, searching, time complexity, and Big O notation

2.1Git fundamentals - commits, branches, merges, rebases, and resolving conflicts

2.2Pull requests and code reviews - how to give and receive feedback on code

2.3Branching strategies - feature branches, GitFlow, and trunk-based development

2.4Working in a team codebase - conventions, documentation, and not breaking things for others

3.1How the web works - HTTP, REST, client-server architecture, and APIs

3.2Frontend basics - HTML, CSS, JavaScript, and how they interact in the browser

3.3Backend basics - servers, databases, request handling, and building a simple API

3.4Authentication and security fundamentals - passwords, tokens, and common vulnerabilities

4.1Relational databases - tables, relationships, SQL queries, and joins

4.2Database design - normalisation, primary keys, foreign keys, and schema design

4.3ORMs and query builders - how they abstract the database and when to go raw SQL

4.4NoSQL databases - document stores, key-value stores, and when to use them instead

5.1Why testing matters - bugs, regression, and the cost of defects found late

5.2Unit testing - writing tests, test coverage, and test-driven development basics

5.3Integration and end-to-end testing - testing components together and the full user flow

5.4Code quality - linting, formatting, code review standards, and writing readable code

6.1SOLID principles - single responsibility, open-closed, and why they make code maintainable

6.2Design patterns - factory, singleton, observer, and when to apply them

6.3Separation of concerns - layered architecture, MVC, and keeping code organised

6.4Refactoring - recognising bad code, improving it safely, and when to leave it alone

7.1The development lifecycle - local development, staging, and production environments

7.2CI/CD pipelines - automated testing, build, and deployment workflows

7.3Containerisation basics - Docker, images, containers, and why they matter

7.4Cloud fundamentals - what the major providers offer and how junior engineers interact with them

8.1Debugging methodology - reproducing bugs, isolating causes, and fixing without breaking other things

8.2Using developer tools - debuggers, logs, profilers, and network inspectors

8.3Reading error messages and stack traces - how to decode them and find the actual problem

8.4Asking for help effectively - how to write a good bug report or question for a senior engineer

9.1Agile and Scrum - sprints, standups, retrospectives, and how engineering teams actually work

9.2Estimating work - story points, time estimates, and why it is hard

9.3Communication as a junior engineer - asking questions, giving updates, and flagging blockers

9.4Growing in the role - how to learn fast, take feedback, and progress from junior to mid-level

10.1Coding interview fundamentals - data structures, algorithms, and practising on a whiteboard or screen

10.2System design basics - how to approach an entry-level system design question

10.3Behavioural questions - learning from mistakes, working in a team, and handling feedback

10.4Salary negotiation, technical questions to ask about the codebase, and how to evaluate a junior engineering role