Jon Coppeard
Staff Software Engineer at Mozilla
England, United Kingdom
Summary
👤
Senior🎓
Top SchoolJon Coppeard is a Staff Software Engineer based in England with nearly two decades of C++ experience focused on systems and embedded software, and 14 years of professional experience in memory management and language runtimes. As tech lead for SpiderMonkey's garbage collector at Mozilla, he drives memory-management design and contributes to JS language features like modules and FinalizationGroup. His background includes kernel-level memory subsystem work at Nokia and long-term systems development at Symbian, giving him deep low-level and OS-facing expertise. An active open-source contributor, he has improved SpiderMonkey GC internals and helped harden Web Platform Tests around JavaScript module loading and dynamic imports. He combines research-grade understanding from a Computer Science education at Cambridge with pragmatic engineering instincts for robust, spec-compliant implementations. Notably, his contributions span both engine internals and cross-browser test suites, reflecting a rare blend of implementation and standards-level testing experience.
14 years of coding experience
9 years of employment as a software developer
Computer Science, Computer Science, Computer Science, Computer Science at University of Cambridge
Github Skills (20)
javascript10
c-language10
testing10
test-runner10
memory-management10
javascript-engine10
dom10
web-standards10
script-engine10
html10
cprogramming-language10
test-automation10
garbage-collection10
gecko7
blink7
Programming languages (10)
Github contributions (5)
mozilla/gecko-dev
Jan 2013 - Jan 2023
SUPERSEDED by https://github.com/mozilla-firefox/firefox. Read-only Git mirror of the Mercurial gecko repositories at https://hg.mozilla.org
Role in this project:
Back-end Developer
Back-end DeveloperContributions:2959 commits in 10 years 2 months
Contributions summary:Jon's commits primarily involve changes to the JavaScript engine (SpiderMonkey), specifically related to garbage collection. They added test cases and modified code for memory management, focusing on areas such as weak maps, the buffer allocator, and handling of object slots. Additionally, the user contributed to code related to modules and other aspects of the engine, contributing to improving the memory management of the JavaScript engine.
firefoxgit-mirrormercurialmozilla-firefox
web-platform-tests/wpt
Aug 2017 - Jul 2021
Test suites for Web platform specs — including WHATWG, W3C, and others
Role in this project:QA Engineer / Test Automation Engineer
QA Engineer / Test Automation EngineerContributions:10 commits, 1 PR, 2 comments in 3 years 11 months
Contributions summary:Jon primarily contributes to the web platform tests for the WPT repository. They focused on improving and updating existing tests related to JavaScript module loading, error handling, and dynamic imports within the context of the script element. The contributions involve adapting tests to changes in browser behavior and ensuring the test suite's coverage of web standards. The user demonstrates a strong understanding of web standards, testing methodologies, and browser compatibility.
w3ctestingtest-automationbrowserwhatwg
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