• Build evaluation suites for LLM and ML features: curated test sets, scoring against reference answers, LLM-as-judge where it is justified, and human review where it is not. • Define what "good enough" means with the delivery team before launch, in numbers a client can accept, and hold releases to it. • Test retrieval pipelines end to end, covering chunking and indexing, retrieval quality, grounding of the final answer, and behaviour when the right document is simply not there. • Write regression tests that tolerate non-deterministic output, using semantic similarity, structured-output validation, tolerance bands, and repeated sampling rather than exact string matching. • Cover failure modes that matter to clients: hallucination, prompt injection through user or document content, leakage of data across tenants or sessions, refusal and over-refusal, and degradation on Thai-language input. • Track cost and latency alongside accuracy, so that a quality improvement that triples token spend is visible before it ships. • Detect drift after release by comparing production samples against the baseline, and raise it early rather than after the client does. • Design and maintain automated test suites for APIs, services, data pipelines, and web applications built for client projects. • Run tests in CI, keep them fast and stable, and treat a flaky suite as a defect in its own right. • Set the test strategy at the start of an engagement: what gets automated, what stays manual, what the exit criteria are, and what evidence the client will receive. Requirements • 4-5 years in test automation, QA engineering, or software engineering with substantial testing ownership. • Strong programming ability in Python, or in TypeScript or Java with the willingness to work primarily in Python. • Hands-on experience testing an LLM or ML-based product in production or close to it. • Practical command of at least one automation framework such as Pytest, Playwright, Cypress, or RestAssured, and experience running suites in CI. • Working knowledge of API and data testing, including SQL and validating data through a pipeline. • The judgement to decide what deserves automation and what does not, and to say so when a suite is producing noise rather than signal. • Clear written and spoken communication in Thai and English. Benefits • Hybrid Working options with Flexible Working Hours. • Your Choice of Gear: Mac or Windows? You pick your preferred work equipment. • Comprehensive Group Health Insurance. • Monthly Grab Transportation credits. • Job-related training courses and certificate fee coverage. • 10+ days of annual leave. • Free snacks and drinks available at the office.