A guide to hiring a QA engineer
A QA engineer is the person who checks that your software does what it should, for real users, before it goes live. QA stands for quality assurance. The work covers testing by hand, writing automated tests, checking APIs and reporting problems in a way developers can act on. If your releases feel risky, or customers find bugs before you do, a QA engineer is often the next hire to consider.
What a QA engineer actually owns
The job is wider than clicking through screens. A QA engineer reads the plan for a feature and asks what could go wrong. They write test cases, run them and explore the parts a script would never try. They keep a regression suite, so old features are checked again after each change. They also look after the test environment and the test data, because tests are only as reliable as the setup under them.
Manual and exploratory testing
Manual testing is a person using the product and judging the result. It finds the awkward bugs: a button that works but is hard to see, a form that breaks on a long name, a step that makes no sense on a small screen. Exploratory testing adds a goal and notes, so the session is focused and the findings can be repeated. Both matter most for new features, where no automated test exists yet.
Test plans and test cases
A test plan says what will be tested, in what order and on which browsers and devices. Test cases break that into steps with an expected result. A good QA engineer ranks them by risk, so payment and sign-in are checked first and a rarely used page later. The plan should be short enough that people read it, and updated when the product changes.
Automated tests with Playwright, Cypress and Selenium
Automated tests run the same checks on every build. Playwright, Cypress and Selenium are open source tools that drive a real browser and click through your product like a user would. They are best for flows that rarely change, such as sign-up, sign-in and checkout. They are slower to write than a manual check, so a QA engineer chooses carefully what to automate and keeps the suite tidy. A suite no one trusts is worse than no suite at all.
API testing
Many products talk to a server through an API, and bugs often hide there. A QA engineer checks that each call returns the right data, handles bad input with a clear error and respects permissions. Tools such as Postman help with this, and the same checks can also be written in code and run in your pipeline. API tests are quick and stable, which makes them a good place to start automating. Your back end developers can then fix what the tests find.
CI pipelines
A CI pipeline builds your code and runs checks each time someone proposes a change. When tests run there, problems show up within minutes and not on release day. A QA engineer helps decide which tests run on every change and which run overnight, and makes sure the reports are easy to read. If the pipeline is new, a DevOps engineer can help set it up.
Mobile testing
Phones add many combinations: different screen sizes, system versions and network speeds. A QA engineer tests on real devices where it matters, uses emulators for quick checks and knows what each one cannot show, such as battery use or a weak signal. For repeat checks, Appium can automate iOS and Android apps. If automation is the main need, see our Appium developers.
Bug reports developers can use
A bug report should answer four questions: what did you do, what did you expect, what happened and where is the proof. A screenshot, a short recording or a log makes the fix far faster. A good QA engineer also notes how often it happens and who it affects, so the team can decide what to fix first. This is a skill worth testing in the interview, because it saves hours every week.
Flaky tests
A flaky test passes and fails with no change in the code. It might wait for a fixed time instead of for the page, share data with another test or depend on a slow service. Flaky tests train people to ignore red results, and then a real bug slips through. A strong QA engineer treats flakiness as a bug in the test and fixes the cause instead of re-running the build until it goes green.
How a QA engineer differs from other roles
A software engineer builds the product and tests their own code with unit tests. A QA engineer looks at the whole product from outside, which catches a different kind of problem. A front-end developer cares how the page looks and behaves, while a QA engineer checks that it does so across browsers and devices. You do not need to choose one or the other. Developers and testers who work together find more bugs than either does alone.
When a QA engineer makes sense
- Bugs reach customers after each release.
- Developers spend hours clicking through the product before every launch.
- You are about to launch, and you want someone to try to break it first.
- You want a regression suite and a clear release checklist.
- Your tests exist but fail at random, and nobody trusts them.
If your product is tiny and changes once a month, careful testing by the developers may be enough for now. A QA engineer tells you that honestly, and helps you set up simple checks you can grow from.
Reading a QA engineer’s background
Ask for an example of a bug they found, how they found it and what changed afterwards. Ask to see a test they wrote and talk it through. Listen for how they decide what to test first. A list of tools tells you little, but a tester who can explain why a check matters is usually a strong hire. Also read one of their bug reports if they can share one with private details removed.
Interview questions to try
- How would you test a sign-up form, and what would you test first?
- When would you automate a check, and when would you leave it manual?
- What do you do when a test fails only once in a while?
- How do you write a bug report for a problem you cannot always reproduce?
- How would you handle a developer who says a bug is not a bug?
The best answers give reasons and an example from past work. Be wary of a candidate who only lists tools and never explains how they would decide what matters.
Run a small paid exercise
Give each finalist the same small task from your real product. It could be a short test plan for one feature, a few test cases for a form or a review of a page with known bugs. Pay for the time. Then compare what each person found, how they ranked it, how clearly they wrote it up and what questions they asked about the product.
Agree how the work is kept healthy
Agree where test cases live, who reviews new tests and how bugs move from found to fixed. Set up test accounts and a test environment that does not touch real customer data. Keep the repository, the test tools and the accounts in your own name, with a separate login for each person. Then nothing is lost if the people change.
Settling in
Give your QA engineer access to the product, the issue tracker and the people who know the product best. A short walkthrough of how you release helps more than a long document. A weekly call and one shared board keep progress easy to see. Share the known weak spots early, such as an old checkout flow or a part of the app that breaks often, because that is where a tester adds value fastest.
Mistakes to avoid
- Trying to automate everything on day one.
- Hiring for a list of tools instead of for how a person thinks about risk.
- Letting testing start only after the code is finished.
- Treating bug reports as blame, and not as shared information.
For related skills, see our JavaScript developers when your tests are written in JavaScript, or our Python developers when your team prefers Python for test code.