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Life & fun · January 2, 2023

Spall – WASM-based profiler for JavaScript and C and Odin

[I'm the author] Spall is a web-accessible profiler that I made to help my web-dev friends load gigabyte+ JSON traces without lunch-break-long load times. Recently, Spall got experimental support for auto-tracing with binary traces (along with an in-progress native-port, to give it more memory headroom), which was used to help track down and fix some hard-to-spot lock contention issues in the Odin-language compiler. I demoed it at the Handmade Seattle conference in October, https://guide.handmade-seattle.com/c/2022/spall/, with a head-to-head against Perfetto,…

Spall – WASM-based profiler for JavaScript and C and Odin launched on January 2, 2023 with 83 votes, #614 of 3,901 launches that month and more than 90% of that year's launches. The site was still online in September 2026, 3 years on.

Visit gravitymoth.com ↗Alternativestop 16% of January 2023

In plain words

Spall is a web-based profiler designed to quickly load and analyze large JSON trace files for performance analysis. It supports JavaScript, C, and Odin, and features experimental binary trace auto-tracing capabilities. The tool was built to handle gigabyte-scale traces efficiently and has been used to identify performance issues like lock contention in compiler development. Spall runs in the browser and offers an alternative approach to other profiling tools.

written from the facts on this page · September 2026

From the sources

Spall Home

Need bigger traces, or more data about your data? We've got a native version onfrom gravitymoth.com

In the maker’s words, at launch

[I'm the author] Spall is a web-accessible profiler that I made to help my web-dev friends load gigabyte+ JSON traces without lunch-break-long load times. Recently, Spall got experimental support for auto-tracing with binary traces (along with an in-progress native-port, to give it more memory headroom), which was…

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