WebCompat Engineer (Contract) - Diagnose & Patch Browser Breakage

Mozilla; United Kingdom; On-site; GBP 60,000 - 90,000; Full time

Job summary

Mozilla in the United Kingdom is looking for a WebCompat engineer to reduce Firefox's bug backlog by diagnosing long-tail site-breakage issues and by writing interventions or simple fixes (often with AI assistance). You turn a large queue of reports into actionable, verifiable bugs.

Responsibilities include finishing diagnoses, reproducing reports, and triaging incoming breakages; you will work closely with developers to land patches and improve cross‑browser compatibility across the web.

Qualifications

• Solid web development (HTML, CSS, JavaScript) and comfort debugging real-world site breakage.
• Fluent with browser devtools and cross-browser diagnosis.
• Comfortable using AI tooling to speed up diagnosis and fixes.

Responsibilities

• Finish diagnosing, or verify the diagnosis of, long-tail WebCompat bugs.
• Write WebCompat interventions where appropriate.
• Write simple fixes (AI-assisted) and land them.
• Reproduce and triage incoming site-breakage reports.

Skills

HTML/CSS/JavaScript

Browser devtools

Cross-browser diagnosis

AI tooling for debugging

Tools

Gecko engine

Job description

Mozilla in the United Kingdom is looking for a WebCompat engineer to reduce Firefox's bug backlog by diagnosing long-tail site-breakage issues and by writing interventions or simple fixes (often with AI assistance). You turn a large queue of reports into actionable, verifiable bugs.

Responsibilities include finishing diagnoses, reproducing reports, and triaging incoming breakages; you will work closely with developers to land patches and improve cross‑browser compatibility across the web.