SDET

An SDET, or Software Development Engineer in Test, is a QA engineer who writes code to test software, building automation frameworks, test tools and CI pipelines. The role combines testing judgment with developer skills and usually pays more than manual QA roles.

What does an SDET do day to day?

• Builds and maintains automated tests for the UI, APIs and services, often in Java, Python or JavaScript.
• Designs the test framework: structure, reporting, test data and how tests run in CI.
• Reviews pull requests from a testing angle and helps developers write testable code.
• Investigates failures and flaky tests, and decides which risks need automated checks.

SDET vs QA engineer

A manual QA engineer focuses on test design and exploratory testing. An SDET does that too, but spends most of the time writing code. Many people move into the role from QA by learning one programming language and one framework well, such as Selenium or Playwright, and then adding CI. See SDET vs QA engineer for a full comparison.

Read the full guide: How to Become an SDET in 2026: The Complete Roadmap