Snr Code Reviewer - HTML/CSS

About OpenTrain

OpenTrain is a central job board for data-labeling and AI-training work, aggregating live opportunities from many AI companies and labeling platforms into one place. Creating an OpenTrain account is free, and applying takes only a few minutes.

This listing represents work that helps build next-generation AI design tools by ensuring human-reviewed HTML/CSS examples are accurate, accessible, and safe.

About AI Training Work

AI training (data labeling / annotation) is the human process that teaches models how to behave. For design and front-end tasks, that means humans inspect, correct, and rate generated HTML/CSS so models learn best practices for markup, styles, and accessibility.

These roles are typically fully remote, flexible, and accessible to experienced practitioners; contributors directly shape model behavior through careful, high-quality annotations and feedback.

The Role

You will be a senior front-end code reviewer auditing annotator reviews of AI-generated HTML/CSS snippets. Work is remote, contractor/part-time, and requires 20+ hours per week.

Compensation: hourly pay at USD 23/hour. This role is worldwide (remote) and focused on high-quality, consistent annotation to train AI design systems.

• Employment type: Contractor, part-time
• Time requirement: 20+ hours per week
• Pay: $23 per hour (USD)
• Remote / worldwide

What You'll Do

Evaluate annotator-submitted ratings and corrections of AI-generated HTML/CSS by spinning up quick sandboxes, verifying implementation, and confirming the submission meets the original prompt and quality rubric.

Provide clear, concise written feedback on mis-ratings and borderline cases, correcting annotations where needed and explaining the rationale so contributors and models learn from the change.

• Validate semantic HTML5 usage, ARIA roles, and SEO-friendly markup against the prompt and accessibility standards.
• Test responsive behavior across breakpoints and verify consistent rendering across modern browsers and devices.
• Check modern CSS features (Flexbox, Grid, custom properties, container queries, @layer) for performance and maintainability.
• Identify anti-patterns such as excessive specificity, unnecessary layout shifts, or fragile hacks and recommend fixes.
• Spot security issues in markup and styles (XSS, content injection, clickjacking risks) and flag them appropriately.
• Use automated tools (Lighthouse CI, axe-core, Playwright) and visual-diff platforms (Percy, Chromatic) when applicable to support judgments.

Requirements

You must have extensive, hands-on experience reviewing or building front-end code and be comfortable delivering constructive, concise feedback in written English (B2+ CEFR). Do not apply unless you meet the stated requirements.

• 7+ years professional experience in front-end development, QA, or dedicated code-review roles focused on HTML and CSS.
• HTML5 mastery: semantic elements, ARIA roles, microdata, and SEO-friendly markup.
• CSS expertise: Flexbox, Grid, custom properties, logical properties, container queries, @layer; familiarity with Sass/PostCSS.
• Responsive & cross-browser skills: fluid, breakpoint-driven layouts that render consistently across modern browsers and devices.
• Accessibility leadership: strong grasp of WCAG 2.2, ARIA patterns, color-contrast rules, and assistive-technology testing.
• Performance optimization: familiarity with Web Vitals, critical CSS, lazy loading, and minimizing layout shifts.
• Security awareness: ability to spot and mitigate XSS, content-injection, and clickjacking risks in markup and styles.
• Testing & validation experience with tools such as Lighthouse CI, axe-core, Playwright, and visual-diff platforms.
• Toolchain fluency with Dockerized environments, modern build tools (Vite, webpack), and version control/code-review platforms (GitHub/GitLab).
• Excellent written English for clear, constructive feedback and mentoring.

Nice To Have

These are not required but will help you be more effective from day one.

• Exposure to LLM evaluation or data-labeling workflows.
• Familiarity with design-system tools such as Storybook or Figma.
• Experience mentoring peers on front-end standards and best practices.

How It Works

Apply through OpenTrain by creating a free account and submitting your profile. Shortlisted reviewers will be invited to a brief qualification exercise to demonstrate code-review judgment and written feedback clarity.

Once approved, you'll receive batches of annotator reviews and associated code snippets to audit in a web-based labeling environment or Dockerized sandboxes. Follow the supplied quality rubric for decisions and record concise feedback when you adjust ratings.

• Platform: labeling workflow will use project-specific tools and sandboxes; expect Dockerized environments and standard build tools.
• Deliverables: accurate annotations, corrected ratings, and concise feedback aligned with the rubric.
• Selection step: qualification task to verify review quality and communication skills.