Software Development Engineer in Test (SDET)

Zefr•Marina del Rey, CA

3d•$90,000 - $120,000•Hybrid

About The Position

Zefr is seeking a Software Development Engineer in Test (SDET) with 1-3 years of experience to enhance quality across their APIs, web applications, data pipelines, and AI-powered services. This role emphasizes code-based testing over manual scripts. The SDET will be integrated into product engineering teams, responsible for defining testing strategies, building and maintaining automated tests within a shared framework, and ensuring these tests are integral to every release. Additionally, the role involves monitoring production systems. The ideal candidate views testing as a software engineering challenge, enjoys identifying system weaknesses, and is comfortable testing various components including data, model outputs, screens, and endpoints.

Requirements

1-3 years of experience, ideally as a QA engineer or SDET, with hands-on test automation.
Solid coding skills in at least one language used for test automation (Python preferred; Java, TypeScript, or Go also acceptable).
Experience automating API tests, including request and response validation, schema checks, and negative cases.
Experience with a modern UI end-to-end framework such as Playwright, Cypress, or Selenium.
Working SQL knowledge for querying data completeness and correctness.
Good test design instincts, including understanding of edge cases, boundary values, negative cases, and the test pyramid.
Comfort with Git, pull requests, code review, and running tests in CI/CD pipelines.
Persistence in debugging, including reading logs, inspecting network calls, and querying databases.
Clear written communication skills for bug reports, test plans, and status updates.

Nice To Haves

Exposure to a public cloud (GCP, AWS, or Azure) and containers.
Experience testing data pipelines and orchestration tools (Airflow, dbt, Great Expectations, Elementary) or data warehouses (Snowflake, BigQuery).
Experience testing ML models or LLM-powered features, including evaluation datasets and handling non-deterministic outputs.
Experience testing AI agents or MCP servers, or using AI coding assistants.
Familiarity with observability and alerting tools (e.g., Datadog, Grafana, Cloud Monitoring, PagerDuty) and synthetic monitoring.
Experience with performance and load testing tools (k6, Locust, JMeter).
Experience with ad tech, digital media, or large third-party platform APIs (Google Ads, Meta, TikTok, Snap).
Frontend knowledge (React) for testing framework upgrades and migrations.
Basic understanding of security for test environments, such as managing secrets.

Responsibilities

Plan testing for each feature, including happy paths, edge cases, and negative cases.
Build and maintain test automation for REST and GraphQL APIs, backend services, web UIs, and third-party partner APIs using a shared code-based framework.
Review teammates' test code.
Validate data pipelines and data quality, including checks on pipeline outputs (schemas, row counts, freshness, business rules) and defining data SLAs.
Test AI and ML features, including comparing model or prompt versions, validating shadow deployments, and testing AI agents and their tools.
Ensure tests run in CI/CD pipelines, gating merges and deploys.
Maintain test speed and reliability by triaging failures, fixing flaky tests, and optimizing run time.
Validate releases in preview, staging, and production environments.
Build synthetic checks, dashboards, and alerts for production quality monitoring.
Investigate issues and incidents, reproduce problems, find root causes, write bug reports, and verify fixes.
Assist during high-severity incidents.
Collaborate with engineers, product managers, data scientists, and customer-facing teams.
Translate findings into well-scoped tickets and communicate quality status openly.