Senior QA / SDET Engineer

About LangChain

At LangChain, our mission is to make intelligent agents ubiquitous. We help developers build mission-critical AI applications across the entire agent development lifecycle. Our open source frameworks — LangChain and LangGraph — see over 70+ million downloads per month. Developers rely on LangChain for composable integrations and LangGraph for controllable agent orchestration. Our commercial agent platform, consisting of LangSmith and LangGraph Platform, enables teams to build, test, run, and manage agents at scale across their organization.

Founded in 2023, LangChain powers top engineering teams at companies like Replit, Lovable, Clay, Klarna, LinkedIn, and more.

About the role

In person 5 days / week in San Francisco, CA or New York, NY

We’re hiring a Senior QA / SDET Engineer to own quality across our LangGraph Cloud / Platform and LangSmith products. You’ll define the test strategy, build automation and tooling, and turn flaky, slow, or manual checks into fast, reliable, and observable pipelines. You’ll work closely with Infra, Backend, and Frontend to ship with confidence across Kubernetes-based services, APIs, and UI flows—and you’ll help pioneer quality practices specific to LLM applications (e.g., prompt regressions and evaluation suites).

Own test strategy end-to-end across APIs, services, UI, data, and infra (K8s / Terraform / Helm).

Build and maintain automation : API / integration tests (Python / pytest), E2E / browser tests (Playwright), load / soak tests (k6), contract tests, and smoke checks for production.

Stand up ephemeral test environments in Kubernetes for PRs and release candidates; seed test data and run hermetic suites.

Shift-left quality in CI / CD (GitHub Actions) : parallelization, caching, deterministic seeds, flake tracking, and quality gates.

Observability for tests : rich failure artifacts (videos, logs, traces), Datadog dashboards, and actionable alerts.

Performance & reliability : baseline SLIs / SLOs for critical paths; capacity tests and regression detection.

Partner on incident workflows : reproduce issues, add focused regression tests, and improve runbooks / postmortems.

Documentation : high-signal test plans, playbooks, and contributor guidelines for writing good tests.

Example projects you might own

A PR-ephemeral E2E harness that deploys a minimal LangSmith stack on Docker in CI and runs Playwright + API suites against seeded tenants.

A k6 scenario that simulates multi-tenant traffic with queue / backpressure, surfacing p95 / p99 latency regressions per release.

A flake-budget system that auto-quarantines flaky tests, opens issues with artifacts, and tracks “time-to-deflake”.

How to be successful in this role

3+ years as QA / SDET / Software Engineer focused on test automation for distributed or cloud products.

Strong hands-on experience with Python (pytest) and TypeScript (Playwright, Jest or equivalent).

Familiarity with CI / CD (GitHub Actions preferred) and making pipelines fast, parallel, and reliable.

Solid understanding of API testing , mocking / stubbing, and data setup / teardown.

Comfortable defining quality bars, authoring test plans, and driving cross-team execution.

Bonus

Load / perf testing (k6), observability (Datadog, OpenTelemetry), and property-based testing (Hypothesis).

Experience testing services running on Kubernetes and containers; comfortable with logs, events, and basic kubectl.

Infra awareness : Helm / Terraform basics, Kubernetes networking, and secrets management.

SQL fluency for data validation (Postgres / ClickHouse / BigQuery).

Go / Node / React familiarity for targeted white-box tests and testability improvements.

Compensation & Benefits

Competitive salary and equity stake for role and stage of company. Commensurate with experience.

Annual salary range : $145,000-$195,000 USD for Senior Engineers