How to Become a Software Development Engineer in Test (SDET)

A Software Development Engineer in Test (SDET) is a hybrid role combining software development and quality assurance expertise. SDETs write code to automate testing, build test frameworks, and work closely with developers to ensure software quality throughout the entire development lifecycle. Unlike traditional testers who focus on finding bugs, SDETs use programming skills to prevent defects and build quality into the development process from day one.

What makes this role unique: SDETs possess both development and testing skills, enabling white-box testing where they understand and test the internal code structure. Unlike QA Engineers who often work at the end of development with black-box testing, SDETs are involved from the beginning—designing test strategies, writing unit tests alongside developers, and building infrastructure that enables quality at scale.

Best suited for: Developers who care deeply about quality or testers who want to code at a professional development level. Best suited for those who enjoy building tools and frameworks, solving complex technical problems, and bridging the gap between development and QA teams.

With 250,000 professionals employed nationwide and 8% projected growth, this is a strong career choice. Explore Computer Science degree programs to get started.

You're expected to code at a developer level—interviews often include DSA problems similar to SWE interviews. Role ambiguity can be frustrating: you may feel caught between development and QA without being fully respected by either group. The 'SDET is dead' narrative persists, even though demand is actually strong.

Morning: Review overnight CI/CD pipeline results and investigate any failures. Attend daily standup with the development team (not a separate QA team). Review pull requests for testability and test coverage. Plan coding work for the day.

Afternoon: Write automated tests for new features—often working in the same codebase as developers. Build or improve test framework utilities. Collaborate with developers on making code more testable. Debug complex test failures or production issues. Participate in code reviews.

Core daily tasks include:

• Writing unit, integration, and E2E tests in the production codebase
• Building and maintaining test frameworks and infrastructure
• Code reviews focused on testability and quality
• CI/CD pipeline development and optimization
• Debugging complex test failures and production issues
• Creating mocks, stubs, and test utilities
• Collaborating with developers on test strategy

Essential Tools: Software Development Engineer in Test (SDET)s rely heavily on these core technologies:

• Java/Python/JavaScript: Strong proficiency in at least one production language required. Java remains dominant in enterprise, Python popular for versatility, JavaScript for web-focused testing.
• Playwright/Cypress: Modern web automation frameworks. SDETs with Playwright/Cypress expertise earn 24% more than Selenium-only. Selenium dropped from 78% to 56% adoption (2023-2025).
• JUnit/TestNG/PyTest: Unit testing frameworks—SDETs often write unit tests alongside developers in the same codebase.
• REST Assured/Postman: API testing tools—SDETs often own API test automation and contract testing.
• Jenkins/GitHub Actions: CI/CD pipeline expertise required. SDETs build and maintain test pipelines, not just run them.

Also commonly used:

• Docker/Kubernetes: Containerization for test environments. Many SDETs manage test infrastructure at scale.
• Git (Advanced): Beyond basics—branching strategies, PR workflows, git hooks for pre-commit testing.
• Mocking Frameworks (Mockito, WireMock): Creating test doubles for isolated unit testing. White-box testing skill.
• SQL/Databases: Querying databases for test data setup and verification. Understanding of data integrity testing.
• Performance Tools (JMeter, k6): Load and performance testing design—often SDET responsibility.

Emerging technologies to watch:

• AI-Assisted Testing: LLM-generated code creates more logic bugs, increasing demand for SDETs who can validate AI output.
• Contract Testing (Pact): Microservices require contract testing between services—SDET specialty.
• Chaos Engineering (Chaos Monkey): Testing system resilience under failure conditions.
• Observability Integration: Connecting testing with production monitoring (Datadog, New Relic).

For SDETs, coding portfolio and GitHub projects matter far more than certifications. Focus on demonstrating programming skills through open-source contributions or well-documented personal projects. Cloud certifications are useful if working in cloud-native environments. The new A4Q SDET certification is worth considering for formal recognition of the hybrid skill set.

Beginner certifications:

• See detailed requirements in the sections above

Intermediate/Advanced certifications:

• See detailed requirements in the sections above

Must-have portfolio projects:

• See detailed requirements in the sections above

Projects to avoid: Test-only repositories separate from application code, Simple tutorial implementations without architectural decisions, Selenium-only portfolios when modern frameworks are expected, Projects without CI/CD integration - these are too common and won't differentiate you.

GitHub best practices: Show tests integrated with production code, not in isolation; Document architectural decisions and trade-offs; Include CI/CD badges and pipeline configuration

SDET interviews closely mirror SWE interviews at major tech companies. Expect: coding rounds with DSA problems (LeetCode medium difficulty), system design round (test architecture focus), automation framework discussion, and behavioral. Amazon includes a bar raiser interview. 32% of SDET job listings now require DSA interview skills similar to developers.

Common technical questions:

• See detailed requirements in the sections above

Behavioral questions to prepare for:

• See detailed requirements in the sections above

Take-home assignments may include: Build a test automation framework for a sample application with CI/CD integration; Write unit and integration tests for a given codebase; Design and implement API tests with proper assertions and error handling

Common challenges software development engineer in test (sdet)s face:

• Role ambiguity - caught between development and QA, sometimes not fully respected by either
• Career path uncertainty - unclear progression compared to traditional SWE roles
• The 'SDET is dead' narrative - despite strong demand, the role is constantly questioned
• Undervaluation - testing work sometimes seen as less important than feature development
• Technical debt - inheriting poorly designed frameworks with no time to fix them

Common misconceptions about this role:

• Myth: SDET is a stepping stone to SWE. Reality: It's a distinct career path with its own progression to Staff/Principal levels.
• Myth: SDET is dying. Reality: Demand grew 17% (2023-2025) while traditional dev roles grew 9%.
• Myth: SDETs just write test scripts. Reality: SDETs architect test infrastructure, contribute to production code, and influence quality strategy.
• Myth: AI will replace SDETs. Reality: LLM-generated code creates more bugs, increasing demand for SDETs who can validate AI output.

Software Development Engineer in Test (SDET) vs Q A Engineer:

Software Development Engineer in Test (SDET) vs Test Automation Engineer:

Software Development Engineer in Test (SDET) vs Software Developer:

Your negotiation leverage:

• Modern framework expertise (Playwright/Cypress vs Selenium) commands 24% premium
• DSA/coding skills at developer level
• Experience building test infrastructure at scale
• CI/CD pipeline development (not just usage)

Proven negotiation strategies:

• Research SWE salaries at the same level—SDET should be comparable
• Highlight framework architecture and infrastructure contributions
• Quantify impact: test coverage improvements, bug escape reduction, pipeline optimization
• Ask about career ladder parity with SWE track

Mistakes to avoid: Accepting lower pay than equivalent SWE roles—SDET compensation should be comparable; Not highlighting programming skills equal to developers; Undervaluing infrastructure and tooling contributions

SDET is one of the safest tech jobs during the AI boom. Demand grew 17% (2023-2025) while traditional dev roles grew only 9%. Companies are paying premium for SDETs who can code, know modern tooling, and pass dev-like interviews. BigTech, finance, healthcare, and SaaS all show strong demand. The 'SDET is dead' narrative is inaccurate—the role has evolved, not disappeared.

Hot industries hiring software development engineer in test (sdet)s: BigTech (Amazon, Google, Microsoft) - SDET compensation nearly matches SWE, Fintech - High quality requirements, strong pay, Healthcare Tech - Regulatory testing needs drive demand, SaaS Companies - Continuous deployment requires embedded SDETs, AI Companies - LLM-generated code increases need for quality validation

Emerging trends: SDET demand up 17% (2023-2025) vs 9% for traditional dev roles, DSA interviews now required for 32% of SDET positions, Playwright/Cypress expertise commands 24% salary premium over Selenium, LLM-generated code creating more logic bugs—increasing SDET value