Senior Rust Backend Developer — AI Tool Evaluation

About OpenTrain

OpenTrain is the #1 platform for finding and building careers in AI training and data labeling. We help people discover projects, consolidate freelance opportunities, and build a unified AI training portfolio they control so specialized work in this growing industry is easier to track and grow into a durable career.

Why AI training matters

AI systems learn from human examples—people annotate, test, and review data so models behave the way we expect. That human feedback work is one of the fastest-growing ways to contribute to AI, and it’s often remote, flexible, and accessible. This role sits at the intersection of backend engineering and practical AI evaluation: you’ll shape how developer-facing AI tools perform in real workflows.

The role

OpenTrain is hiring a remote Rust Backend Developer on a contract, part-time basis to focus on backend APIs and hands-on testing of AI coding tools. You will design and improve REST and GraphQL endpoints, support validation and security, perform database migrations and schema changes, and participate in concentrated testing bursts that produce incident reports, bug traces, screenshots, surveys, and structured feedback for a research team.

The client for this project is OpenTrain; the role requires strong communication, an eye for reproducible bug reports, and familiarity with AI-assisted coding tools—Cursor experience is especially valued.

What you'll do

• Build and optimize backend APIs using Rust with REST and GraphQL endpoints.
• Implement and review data validation, robust error handling, and API security best practices.
• Manage database migrations, schema changes, and related backend maintenance tasks.
• Perform hands-on testing of AI-powered coding tools (notably Cursor) and document issues with clear reproduction steps, traces, and screenshots.
• Participate in 4-day intensive testing bursts and produce post-burst summaries and actionable feedback.
• Discuss findings and propose improvements in a dedicated Slack channel with the research team.

Requirements

• Strong professional experience as a backend developer with Rust expertise.
• Experience designing and maintaining RESTful and GraphQL APIs.
• Knowledge of backend validation, error handling, API security, and database migrations.
• Strong written and verbal communication skills for clear bug reports and research feedback.
• Familiarity with AI coding tools such as Cursor and interest in evaluating developer workflows.
• Availability for 20+ hours per week and participation in concentrated testing bursts as scheduled.

Helpful background

• Visible open source contributions in Rust or backend tooling.
• Experience evaluating experimental developer tooling and measuring impact on workflows.
• Interest in how AI assists software development and how to improve model behavior in real use.

Logistics & pay

This is a remote contract position, open worldwide. Employment types: contractor, part-time. Language: English. Time commitment is 20+ hours per week with periodic intensive testing bursts.

Compensation is hourly in USD — posted as up to $90/hr (hourly range shown: $30–$90/hr).

How applications work

If this match fits your skills and schedule, apply through OpenTrain with a brief summary of your Rust backend experience, links to relevant open-source work (if any), and notes about your experience evaluating AI coding tools like Cursor. Be prepared to demonstrate past API work and describe how you structure reproducible bug reports and incident traces.