Backend Engineer (AI)

Location: Hybrid in London or Paris. The London posting requires three office days per week and a trip to Paris approximately every 4–6 weeks.

Company

H builds computer-use agents and the models behind them, providing a managed API and deploying agents into enterprise workflows.

What you will do

• Build and operate the evaluation framework for benchmarks across web applications, desktop software, and command-line environments.
• Integrate benchmarks for researchers and forward deployed engineers while shortening the integration path for future evaluations.
• Define benchmark standards and implement checks that enforce reliable, reproducible results.
• Improve scheduling, cluster utilization, observability, and evaluation performance across approximately 50 benchmarks, growing toward 100–200.
• Work with customers to identify workflows they want measured and automate the flow of results into evaluation harnesses and models.

Requirements

• 5+ years of backend development experience with production Python.
• Experience building test, QA, or evaluation tooling used by other engineering teams.
• Experience operating distributed systems on Kubernetes in a public cloud; AWS experience is valuable.
• Experience delivering systems end to end, including REST or GraphQL APIs and third-party integrations.
• Knowledge of relational and non-relational databases and message queues such as SQS, RabbitMQ, or Kafka.
• Experience implementing metrics, tracing, and monitoring from the start of a project.

Nice to have

• Experience measuring LLM quality or building agents.
• Experience with Docker, virtual machines, Temporal, Dask, FastAPI, PostgreSQL, Grafana, or Datadog.
• Experience automating web or desktop software with Playwright, Selenium, or browser extensions.
• Experience setting engineering standards through code reviews, design reviews, or mentoring.

Culture & Benefits

• Full-time hybrid work in London or Paris.
• Close collaboration with researchers and forward deployed engineers.
• The role offers ownership of areas such as run scaling, observability, or related benchmark groups.
• Competitive package.

Hiring process

• 30-minute call with the Talent team.
• 60-minute technical challenge and 60-minute system design interview.
• 30-minute final conversation with the VP of Engineering, approximately 3.5 hours in total.