Buz: a Bun fork rewritten in modern Zig, with sub-second incremental builds

A project posted on ziggit.dev announces a drop-in replacement for Bun, rewritten in modern Zig, with sub-1s incremental builds. The question: does the JavaScript runtime really need a fork?

The fact

A project named Buz - presented by its authors as "a drop-in replacement for Bun using modern Zig, with sub-1s incremental builds" - appeared on ziggit.dev on July 24. The fork claims compatibility with Bun while modernizing the underlying Zig stack (Bun had frozen its Zig version at the time of release). The project was relayed on the HN front page.

Our analysis

Two tensions coexist in the JavaScript runtime ecosystem. On one hand, Bun has consolidated a user base that loves speed but tolerates patch delays poorly. On the other hand, the Zig community evolves at a pace that has left Bun on an old version of the compiler. Buz responds to this friction. But a drop-in fork lives or dies on maintenance: "sub-1s incremental" is spectacular at the announcement, unmanageable if the team doesn't exist behind it. And a drop-in that follows a rapidly evolving API spends its time chasing the upstream.

To watch

• Project signature: who maintains, what commit history, what CI?
• Reaction from Jarred Sumner (Bun): ignore, rebase, or upstream-merge ideas?
• Adoption: how many Bun projects install Buz in side-by-side mode within 30 days?