By the numbers

Quick statistics about the Bun repository as of e257f2d8 on main.

Repo size

Metric	Value
Total commits	15,190
Unique commit authors	906
First commit	2021-04-17 ("woot")
Latest tag	bun-v1.3.13
Default branch	main

Activity

Window	Commits
Last 90 days	~700
Last 365 days	~2,400

%%{init: {'theme':'default'}}%%
graph LR
    subgraph "Recent contributors (last 90 days)"
        A[robobun: 317 - automated PR-merge bot]
        B[Jarred Sumner: 149]
        C[Dylan Conway: 128]
        D[SUZUKI Sosuke: 32]
        E[Alistair Smith: 24]
        F[Ciro Spaciari: 19]
    end

The robobun account is a merge / changelog bot, so its commit count reflects automation rather than human review traffic.

Language breakdown

Approximate counts of src/** files by extension:

Language	Files	Notes
TypeScript (.ts, .tsx)	~2,575	Built-in modules (src/js/), codegen, packages.
JavaScript (.js)	~3,963	Bundled/generated artifacts and a few hand-written builtins.
Zig (.zig)	~1,220	Core runtime.
C / C++ headers (.h)	~776	JSC bindings + C interop.
C++ (.cpp)	~570	JSC bindings.
Rust (.rs)	~11	A small handful of helpers.

Notable file sizes (Zig)

File	Bytes	Subsystem
src/js_printer.zig	~260 KB	JS printer
src/css/css_parser.zig	~298 KB	CSS parser
src/cli/test_command.zig	~211 KB	Test runner CLI
src/resolver/resolver.zig	~206 KB	Module resolver
src/cli/install_command.zig	~184 KB	Package manager CLI
src/bun.js/api/server.zig	~170 KB	HTTP server
src/sys.zig	~165 KB	Cross-platform syscalls
src/transpiler.zig	~72 KB	Runtime transpiler
src/Watcher.zig	~27 KB	File watcher
src/crash_handler.zig	~96 KB	Crash handler

Vendored dependencies

Library	Purpose
WebKit / JavaScriptCore	The JS engine.
BoringSSL	TLS, crypto, hashing.
mimalloc	Allocator.
zlib-ng / libdeflate / brotli / zstd	Compression.
c-ares	Async DNS.
libuv	Windows event loop.
picohttpparser	HTTP/1 parsing.
ls-hpack / ls-qpack / lsquic	HTTP/2 + HTTP/3.
lol-html	HTML rewriter.
libarchive	Tar / zip.
Highway	Portable SIMD.
Tracy	Optional profiler.
nodejs (headers)	N-API + V8 ABI compat.
TinyCC (oven-sh fork)	FFI JIT.
Zig	Compiler / stdlib.

Releases

Tag	Date	Note
bun-v0.0.0-10 (first tagged build)	2021	"Bun" name was already chosen.
bun-v0.1.0	2022-07-05	First minor.
bun-v0.5.0	2023-01-18
bun-v1.0.0	2023-09-07	"Stable" announcement.
bun-v1.1.0	2024-04-01	Major Windows support, bake.
bun-v1.2.0	2025-01-21	New text-based lockfile (bun.lock).
bun-v1.3.0	2025-10-10	Latest minor (1.3.x ongoing).
bun-v1.3.13	most recent	Patch release.

Hot subsystems by recent edit volume

The most-modified directories in the last 90 days (rough count from git log):

1. src/install/ — package manager work.
2. src/bake/ — dev server / SSR.
3. src/bun.js/api/ — runtime APIs.
4. src/bun.js/webcore/ — Web APIs (fetch, streams).
5. src/sql/ — Postgres + MySQL improvements.

Use git log --since="90 days ago" --name-only -- <dir> | wc -l to recompute.

Test suite

Area	Approx files
test/js/bun/	hundreds
test/js/node/	hundreds (Node compat is a major axis)
test/js/web/	dozens
test/cli/	dozens
test/bundler/	dozens (each test bundles a fixture)
test/regression/issue/	one file per regression
test/integration/	dozens (real workflows)

The whole suite takes the better part of an hour on CI; locally, run only what's relevant. See Testing.