Comment by Jarred
2 days ago
I have learned so much reading Andrew’s code and as I said in the original post: Bun would never have happened without Zig.
> 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.
Fuzzilli integration: https://github.com/oven-sh/bun/pull/24826
Merged PRs fixing issues Fuzzilli found in Bun’s Zig code:
- https://github.com/oven-sh/bun/pull/28926
- https://github.com/oven-sh/bun/pull/28934
- https://github.com/oven-sh/bun/pull/29255
- https://github.com/oven-sh/bun/pull/29210
- https://github.com/oven-sh/bun/pull/29199
Searching “Fuzzilli” shows more PRs: https://github.com/search?q=repo%3Aoven-sh%2Fbun+is%3Apr+Fuz...
Note that Andrew's since removed the “outright fabrication” bit from his post. No indication of the edit itself though, which is a choice.
Original post: https://archive.is/wNLqY
Updated version: https://archive.is/TpsUW
It is a choice indeed. Well worded.
Andrew means the zig build test --fuzz command probably the built in zig fuzzer, that's the tool that is in his scope.
Not sure I follow. Is "fuzzing their Zig code" somehow related to adding a Fuzzilli integration to Bun?
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 relationship, 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...
AFAIU fuzzing code != fuzzing results. Through skimming it seems that integration tests were using fuzzing, but I would call it fuzzing the code itself.
From "product" perspective there's no difference, but in program-compiler perspective (and e.g. raising bugs about compiler), Fuzilli isn't fuzzing.
Per Wikipedia > (then...) The program is then monitored for exceptions such as crashes, failing built-in code assertions, or potential memory leaks.
As for myself, I wouldn't use term fuzzing for integration testing such the one used by Fuzilla. I always caught it dynamic testing, scenario testing and in bigger cases property based tests. Fuzzing in my mind is reserved to a low-abstraction calls.
Might just be me, though.
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Based on timeline, it seems like both are true. They stopped communicating around the time of the acquisition per OP, which was announced December 3rd, and the PR integrating it is was merged the tail end of November.
Why are you not using hyperlinks and adding links citation style?
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Your links show you used a fuzzer, but that doesn't address the other half of Andrew's statement. Is Andrew misreporting/misremembering your conversations?
EDIT: It's really telling that asking a factual clarification question is somehow downvote worthy. I probably shouldn't be surprised, but this epitomizes the reason online discussions devolve in to flame wars (even moreso than real life, though it happens more and more there as well).
The answer could be as simple as we didn't use a fuzzer until recently so both are accurate. I honestly don't know, which is why I'm asking. Yet somehow just asking is triggering to people.
Or, did the whole Bun team indeed state the otherwise to Zig?
You're a champ, man
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You want to see him address being "a stinky manager", having "beginner energy", choosing to take VC as opposed to "a solid living via crowdfunding", or "already writing slop well before he had access to LLMs"?
Those are all opinions where arguing about them isn't going to be productive.
Countering the accusation of "an outright fabrication" on the other hand is worthwhile because it's a claim that can be countered.
If somebody called me a liar for something that demonstrably wasn't a lie I wouldn't let that stand, either.
> Countering the accusation of "an outright fabrication" on the other hand is worthwhile because it's a claim that can be countered.
Hmm, fuzzing integration was merged 8 months ago. First found bug mentioned 3 months ago. Bun is 4 years old. I think both arguments can be true at the same time based on this evidence. It is entirely possible that for more than 3 years team has said that no fuzzing was done, and the first fuzzing was done just 3 months ago, and this information did not travel.
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Those statements are all consistent with the publicly observable facts like this whole thing going from "I'm experimenting with this" to "this is merged into main now, yolo" within a week or so. The complaints from Jarred on the amount of bugs they've been having is too.
It all checks out.
Bun donates $60,000 per year [month] and Jarred acts with graciousness and soft tones when talking to outside parties. Why do you think it's Jarred's obligation to continue after being insulted for professional dishonesty?
Isn't it Andrew's obligation to show that he was worth that much kindness to begin with?
> worth that much kindness to begin with?
Maybe I'm overly cynical, but I don't know that directing some funding towards the open-source project that is the foundation of your whole tech stack is really "kindness" per se.
When you are vending a devtool to other open-source developers, and making a lot of hay about the specific technology choice, it's basically marketing spend. It's also often a way of buying favour (attention to issues, PRs, etc) from the project maintainers...
> Bun donates $60,000 per month
Per year, not month.
The blog is not worth a reply. It's just a butthurt, petulant rant full of personal attacks.
Dude, that PR is on 25th of November 2025 :) Few weeks before Anthropic acquired Bun.
Without having any opinion on whether or not the Bun team was meaningfully fuzzing their codebase... Andrew's claim was not about whether or not they were, it was noting that the story was different between what they claimed in conversation and what they stated in this article.
All of those commits except the initial integration are from after the acquisition. How do we know this wasn’t done without anyone on the call’s knowledge?
Since there are multiple ways to interpret Andrew's original comment, multiple ways to interpret what his newer edit of it implies, multiple logical reasons each way could have come about, and likely multiple opinions on what the expectations from each side should be... I'm finding myself getting stuck in a loop of trying to understand how/why these considerations are important.
Could you help further explain which interpretations & ways you feel this info is relevant to?