Senior Code Reviewer, HTML/CSS

About OpenTrain

OpenTrain is the #1 platform for finding and building careers in AI training and data labeling. OpenTrain AI hires and contracts contributors for projects that help shape how modern AI systems learn, reason, and perform.

Creating an OpenTrain account is free, and contributors can discover opportunities, build a professional profile, and apply in minutes.

About AI Training and Code Evaluation

AI training is the human side of building artificial intelligence. Specialists review examples, evaluate model outputs, and provide structured feedback so AI systems can become more accurate, useful, accessible, and reliable.

In this role, your front-end expertise will help assess AI-generated HTML and CSS. Your reviews will support the development of next-generation AI design tools while giving you flexible, remote work in a fast-growing technology field.

The Role

OpenTrain AI is seeking Senior Code Reviewers specializing in HTML and CSS to audit annotator reviews of AI-generated code snippets. You will verify whether each submission fulfills its prompt, renders correctly, and follows strong standards for semantics, accessibility, performance, security, and responsive design.

This is a part-time contractor opportunity requiring 20 or more hours per week. The rate is $23 per hour, and the role is available to contributors located in India, the Philippines, or Vietnam.

• Work type: Contractor and part-time
• Time commitment: 20+ hours per week
• Pay: $23 per hour
• Language: English
• Eligible locations: India, the Philippines, and Vietnam

What You'll Do

You will work carefully through annotated HTML/CSS submissions, using a quick sandbox to validate implementation details and compare each review with the applicable quality rubric. Your feedback should be concise, constructive, and specific enough to help correct inaccurate ratings.

• Audit annotator reviews of AI-generated HTML and CSS snippets.
• Verify that code meets the original prompt and renders correctly across breakpoints.
• Assess semantic markup, ARIA usage, responsive behavior, and cross-browser consistency.
• Identify accessibility issues involving WCAG 2.2, ARIA patterns, color contrast, and assistive technologies.
• Review performance concerns such as critical CSS, lazy loading, Web Vitals, and layout shifts.
• Spot security risks including XSS, content injection, and clickjacking vulnerabilities.
• Detect anti-patterns such as excessive specificity and unstable layouts.
• Correct mis-ratings and provide targeted feedback aligned with the quality rubric.
• Help safeguard high-quality data used to train AI design tools.

Required Experience and Technical Skills

This role is intended for an experienced front-end specialist with at least seven years of professional experience in front-end development, QA, or dedicated code review focused on HTML and CSS. You should have excellent written English at B2 level or higher under the CEFR and a proven ability to give clear, constructive feedback.

• Expertise in HTML5, including semantic elements, ARIA roles, microdata, and SEO-friendly markup.
• Deep knowledge of CSS3, including Flexbox, Grid, custom properties, logical properties, container queries, and @layer.
• Experience with Sass and PostCSS preprocessors.
• Proven ability to build fluid, breakpoint-driven layouts across modern browsers and devices.
• Strong knowledge of WCAG 2.2, ARIA patterns, color contrast, and assistive-technology testing.
• Familiarity with Web Vitals, critical CSS, lazy loading, and minimizing layout shifts for strong Lighthouse scores.
• Ability to identify and mitigate XSS, content-injection, and clickjacking risks in markup and styles.
• Experience with Lighthouse CI, axe-core, Playwright, and visual-diff tools such as Percy or Chromatic.
• Comfort with Dockerized environments, Vite, webpack, version control, and GitHub or GitLab pull-request workflows.
• A record of guiding peers on front-end standards and best practices.

Preferred Background

Experience with AI evaluation or data-labeling workflows is helpful but not required. Familiarity with design-system tools can also support the work.

• Exposure to large language model evaluation or data-labeling workflows.
• Familiarity with Storybook or Figma.
• Interest in applying front-end standards to emerging AI-generated code.

Why Join AI Training Work

AI training and data labeling connect specialized human judgment with the development of modern AI. Contributors can apply expertise in areas such as programming, accessibility, and quality assurance while working remotely with flexible scheduling.

• Remote work using a computer and internet connection.
• Part-time flexibility that can fit around other commitments.
• A chance to influence how AI-generated software behaves and improves.
• An accessible path into a rapidly growing AI technology industry for qualified specialists.

How to Apply

Create a free OpenTrain account, build your profile around your HTML/CSS and code-review experience, and apply through OpenTrain. Be prepared to highlight your front-end background, accessibility knowledge, testing experience, and ability to write precise English feedback.