SDET
Also known as: Software Development Engineer in Test
An SDET (Software Development Engineer in Test) is a QA professional who writes production-quality code to build test automation frameworks, tooling, and infrastructure — combining strong software engineering skills with testing expertise. Unlike a manual tester, an SDET is expected to design systems, not just execute test cases against them.
The SDET title (popularized by Microsoft in the 2000s) exists to describe a specific hybrid: someone with the coding ability of a software engineer, applied specifically to testing problems — building the automation framework other testers use, writing tools that generate test data, integrating tests into CI/CD pipelines, and sometimes contributing to production code directly.
Day to day, an SDET's work looks less like clicking through a UI and more like software engineering with a testing focus: designing a page object library, building a custom API testing harness, writing a service that generates realistic synthetic test data, or diagnosing why a test suite has become flaky and fixing the underlying framework issue.
The line between "SDET" and "automation engineer" varies a lot by company — some use the titles interchangeably, others reserve SDET for a more senior, architecture-level role. What's consistent across almost every definition: an SDET is expected to write and review code, not just execute pre-written test cases.
