# Cruller: Bun's Zig Runtime, Continued on Zig 0.16 > Source: > Published: 2026-07-23 05:40:20+00:00 Cruller: a production-focused Bun runtime ported to Zig 0.16 Cruller is a fork of the last Zig-based Bun release, reduced to the parts needed to run already-built production JavaScript servers and ported to vanilla Zig 0.16. Repository: [GitHub - solenopsys/cruller: fork of Bun · GitHub](https://github.com/solenopsys/cruller) The project keeps JavaScriptCore, `Bun.serve` , HTTP/1-3, WebSockets, `fetch` , streams, `Blob` , `Request` /`Response` , static serving, and the module resolver for pre-built JavaScript. It removes the package manager, bundler/transpiler, shell, test runner, most CLI dispatch, N-API, SQL clients, archive support, and other development-oriented subsystems. The interesting part of the port was separating the runtime from Bun’s old patched Zig build integration. Cruller now has a vanilla Zig 0.16 build graph, compatibility shims for APIs changed since Zig 0.15, and a generated-code embedding module so release builds remain portable instead of loading generated JS from the build directory at runtime. The main design decision is to treat this as a runtime, not a general-purpose Bun replacement. A minimal launcher loads a pre-built entrypoint; features that require package installation, bundling, TypeScript transformation, or `bun test` are intentionally outside the scope. Current measurements on Linux x64, compared with the official Bun 1.3.14 binary: - Cruller `ReleaseFast` stripped runtime: 73.0 MiB - Official Bun runtime: 88.5 MiB - Size reduction: about 18% - V8 Crypto pure-JS benchmark: performance parity; Cruller’s median was about 2% higher, within normal run-to-run variance The runtime is still work in progress, but Zig semantic checks, release builds, CJS/ESM entrypoints, Node path tests, and an HTTP `Bun.serve` plus built-in `fetch()` smoke test currently pass. Supported Zig versions - Zig 0.16.0 - Linux x64 is the currently supported build target Suggested topic tags: `showcase` , `zig-0-16` , `llm` AI / LLM usage disclosure AI was used as an engineering assistant for parts of the Zig 0.16 migration, build/debug investigation, and focused test work. The project scope, architecture decisions, review of changes, and build/test verification remain maintainer-directed. This is not a purely AI-generated project.