JavaScript Developer (Frontend) — AI Training Systems

About OpenTrain

OpenTrain is the #1 platform for finding and building careers in AI training and data labeling. The platform helps contributors discover projects, build a unified AI training portfolio, and apply quickly so they can grow a durable freelance career.

OpenTrain connects people to hands-on work that shapes how AI systems behave. Creating an OpenTrain account is free.

About AI training work

AI training (also called data labeling or human feedback work) is the human side of building artificial intelligence: people create, review, and rate examples that models learn from. Contributors annotate code and user interactions, evaluate model outputs, and help models learn to reason and behave safely.

This role sits at the intersection of frontend engineering and AI training: your JavaScript work will directly support the systems and interfaces used to build and evaluate models.

The role

OpenTrain is recruiting a freelance JavaScript Developer to contribute expertise to training next-generation AI systems by building high-quality frontend solutions. This is a remote, contractor, part-time engagement requiring 20+ hours per week.

Experience level: Entry level (the listing also documents extensive frontend responsibilities; please review the required skills below). Language: English. Worldwide applicants accepted.

• Engagement: Freelancer, contractor, part-time (20+ hours/week).
• Labeling/data focus: computer code/programming and evaluation/rating tasks ().
• Pay: Hourly — $30–$90 per hour (the role lists an hourly rate up to $90).

What you'll do

You will design and implement robust frontend features that support AI-training workflows, collaborate with cross-functional teams, and help ensure the applications used to collect and evaluate training data are reliable and usable.

• Design, develop, and optimize robust frontend solutions using advanced JavaScript techniques.
• Translate business and research requirements into intuitive digital interfaces with product and design teams.
• Lead architectural decisions and mentor junior developers (as the project requires).
• Implement modern frontend frameworks and state management to deliver scalable, maintainable applications.
• Conduct code reviews, provide constructive feedback, and promote clean, efficient code.
• Troubleshoot complex issues and resolve performance bottlenecks.
• Stay current with industry trends and propose improvements to development workflows.

Requirements

Candidates must meet the substantive technical requirements listed below. These are explicit expectations for the role.

• Extensive experience building sophisticated web applications with JavaScript.
• Expertise in modern frontend frameworks (React, Vue, Angular) and state management tools.
• Ability to write clean, maintainable, and well-documented code.
• Excellent written and verbal communication skills, with a strong commitment to clarity and collaboration.
• Proven track record of driving frontend architecture and leading development initiatives.
• Strong understanding of web performance optimization and responsive design principles.
• Experience working in remote, distributed teams.

Helpful background

The following are not required but will help you succeed and stand out when contributing to AI-training frontends.

• Experience mentoring or coaching other developers.
• Background building accessible and internationalized web interfaces.
• Familiarity with automated testing, CI/CD pipelines, and version control systems.

Who should apply

This role is a good fit for frontend developers who want to apply real JavaScript engineering skills to the practical task of building and improving the tools used to train AI. If you enjoy clean UI code, performance tuning, and collaborating across teams, apply.

Although the posting lists entry-level experience, the responsibilities include architectural leadership and mentorship—applicants should be comfortable with the required skills above.