MTmtlynch·Jul 9, 2026
Yes, "their" refers to Bun's code, not the Zig compiler's code. Fuzzili is a fuzzing engine for JavaScript, so integrating it into Bun means that Fuzzili is fuzzing Bun.[0]
From the Bun post[1]
> We fuzz Bun's runtime APIs 24/7 using Fuzzilli, the JavaScript engine fuzzer used by V8 & JavaScriptCore
From Andrew Kelley's post today[2]:
> The post claims they were fuzzing their Zig code, while during our calls the whole Bun team told us that they were not fuzzing anything. This appears to be an outright fabrication.
Sumner says that the Bun team has been fuzzing Bun's Zig code. Kelley says that this is a fabrication. Sumner showed proof that the Bun team has been fuzzing Bun's Zig code.
It looks like Kelley is incorrect and made an unfounded claim. The generous interpretation is that at the time Kelley and Sumner had a more collaborative re
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lationship, Sumner was not fuzzing Bun's Zig code, but I'd expect Kelley to check if anything had changed since then before publicly accusing Sumner of lying in this week's Bun blog post.
[0] https://github.com/googleprojectzero/fuzzilli
[1] https://bun.com/blog/bun-in-rust
[2] https://andrewkelley.me/post/my-thoughts-bun-rust-rewrite.ht...