All levels 路 All roles 路 All technologies

Browse All Software Engineer Interview Questions

Every question in one place. Combine filters to narrow the list, or search for a concept, such as closure, JOIN, useEffect or rate limiter.

Download all (PDF)169 questions

13 of 169 questions match

Clear filters
  • ReactEasy

    Why do we need keys in React lists?

    Keys give each list item a stable identity so React can match items between renders and correctly add, remove or reorder them without recreating or mixing up their state.

    Junior 路 Mid-level 路 Performance
  • CSSMedium

    How does CSS specificity work?

    Specificity is the score the browser uses to decide which rule wins: inline styles beat IDs, IDs beat classes/attributes/pseudo-classes, and those beat elements. When scores tie, the last rule in the source wins.

    Junior 路 Mid-level 路 CSS Layout
  • JavaMedium

    What is the difference between checked and unchecked exceptions in Java?

    Checked exceptions (subclasses of Exception other than RuntimeException) must be caught or declared with throws, while unchecked exceptions (RuntimeException and Error) do not have to be handled and usually signal programming bugs.

    Junior 路 Mid-level 路 Programming Fundamentals
  • PythonMedium

    Why should you not use a mutable default argument in Python?

    Default argument values are evaluated once when the function is defined, so a default list or dictionary is shared between every call that does not pass its own, causing data to leak between calls.

    Junior 路 Mid-level 路 Functions & Scope
  • GitMedium

    How do you resolve a merge conflict in Git?

    Open the conflicted files, decide what the final code should be between the conflict markers, remove the markers, run the tests, then stage the files and continue the merge or rebase.

    Junior 路 Mid-level 路 Git
  • BehavioralMediumBehavioral

    How do you answer "Tell me about a production bug you fixed"?

    Walk through how you noticed the issue, limited the impact, found the root cause, fixed it, and what you changed afterwards so the same class of bug could not happen again.

    Junior 路 Mid-level 路 Behavioral Interviews
  • GitMedium

    What is the difference between git reset and git revert?

    git revert creates a new commit that undoes an earlier one and is safe on shared branches; git reset moves the branch pointer back to an earlier commit, effectively removing later commits from that branch鈥檚 history.

    Mid-level 路 Senior 路 Git
  • Software TestingMedium

    How do you deal with flaky tests?

    Treat a flaky test as a bug: quarantine it so it stops blocking the pipeline, reproduce it by running it repeatedly, fix the root cause (usually timing, shared state or external dependencies), then bring it back.

    Mid-level 路 Senior 路 Testing
  • JavaScriptHard

    How do you find and fix memory leaks in JavaScript?

    Take heap snapshots in Chrome DevTools before and after the suspect action, compare what grew, and fix the retaining reference, which is usually a forgotten listener, timer, global variable or unbounded cache.

    Senior 路 Memory Management
  • SQLHard

    How do you optimize a slow SQL query?

    Read the execution plan with EXPLAIN to find full scans and expensive joins, add or fix indexes for the filter and join columns, select only the columns and rows you need, and rewrite predicates so indexes can be used.

    Senior 路 Performance
  • C#Hard

    How do you avoid deadlocks with async/await in C#?

    Use async all the way down instead of blocking on tasks with .Result or .Wait(), and in library code use ConfigureAwait(false) so continuations do not need to return to a captured context.

    Senior 路 Asynchronous Programming