Senior Backend Engineer (Python)

About OpenTrain

OpenTrain is the #1 platform for finding and building careers in AI training and data labeling. We help freelancers discover projects, consolidate proof of work, and grow a durable portfolio of AI-training experience.

• One place to manage AI-training opportunities and show credible experience.
• Built for contributors who want flexible, remote work that helps shape modern AI systems.

About AI training work

AI training (also called data labeling or human feedback) is the human side of building intelligent systems. Contributors create, review, and evaluate the data and interactions that modern AI models learn from — and backend systems are essential to delivering high-quality, real-world inputs at scale.

• Work is 100% remote and often flexible — many projects fit around other commitments.
• No single background is required for the industry, but specialist engineering skills are valuable for infrastructure and tooling roles.

The role

OpenTrain is recruiting for a Senior Backend Engineer (Python) on a contract, part-time basis to design and operate backend systems that support AI-training workflows. This role focuses on building and optimizing APIs, real-time pipelines, and scalable cloud deployments that power data collection, evaluation, and labeling systems.

• Contract, part-time: 20+ hours per week (remote, worldwide).
• Hourly pay: USD, up to $120/hour (range listed $40–$120/hr).

What you'll do

You will develop and improve backend services that process and route labeling and evaluation work, ensuring systems are reliable, performant, and maintainable.

• Design, develop, and optimize APIs using Python and FastAPI.
• Implement scalable solutions on AWS and deploy with Kubernetes.
• Build and maintain real-time systems with WebSockets and message queues.
• Review and refactor legacy code to improve performance and maintainability.
• Produce and maintain clear technical documentation and collaborate with remote teams.

Requirements

Candidates must bring proven, expert-level backend experience and the ability to work autonomously in a distributed environment. Strong written and verbal communication is required.

• Expert-level Python backend development experience.
• Hands-on experience with AWS services and cloud deployment.
• Strong knowledge of FastAPI, WebSockets, Kubernetes, and message queues.
• Excellent written and verbal communication skills.
• Able to work independently in a fast-paced, distributed team.

Helpful background (nice-to-have)

These are not required, but they indicate experience that will help you succeed on AI-driven backend projects.

• Experience building high-impact or AI-driven systems.
• History of working with multidisciplinary, remote teams.

How to apply and next steps

Apply through OpenTrain to be considered for this OpenTrain contractor position. Your OpenTrain profile helps showcase relevant backend and AI-related experience. If selected, expect a technical interview and a short hands-on assessment focused on backend design and debugging.

• Employment type: Contractor, Part-time.
• Languages: English required.
• Labeling context: work supports code/evaluation tasks (computer code programming, evaluation/rating).