Releasing bismar: a source code browser for terminal.

Open any package from npm / jsr / crates / pypi / gems / packagist / github - browse its files with syntax highlighting.

npm install -g bismar (or npx bismar) bismar crate:serde bismar gh:@paulmillr

https://t.co/6enqn36FYS https://t.co/iws12KV0Kb

paulmillr/bismar

Source: https://github.com/paulmillr/bismar

bismar

Browse, weigh, and diff packages from any registry

A bismar is the old Viking hand scale for weighing goods. This one works with npm, jsr, crates.io, rubygems, pypi, packagist, github, gitlab, and the go proxy; allowing to:

1. Browse code in interactive keyboard-friendly navigator
2. Compare diffs between different versions
3. Download files
4. Easily use tool output in machine-friendly non-TTY env

For JS, bismar can also bundle and minify specific exports, with tree shaking.

Used by noble cryptography to ensure bundles stay small.

Usage

npm install bismar — or, without installing, npx bismar js:preact -bs from any directory

usage:
  bismar [<selector>] [--bundle] [--minify] [--size] [--list]
  bismar [-bms] [<selector>]
  bismar --diff <a> <b>

flags:
  <no flag>     open interactive navigator
  -b, --bundle  emit a single-file bundle (JS) / archive (non-JS)
  -m, --minify  (JS only) emit the minified bundle
  -s, --size    list shipped file size stats
      -bs       (JS) bundle sizes
      -bsm      (JS) bundle sizes, minified+gzipped
  -d, --diff    interactive comparison between 2 selectors
      -ds       non-interactive size stats for all files
      -dbs      (JS) diff of bundle sizes
      -dbsm     (JS) diff of bundle sizes, minified+gzipped
  -l, --list    list all public exports
      --clear   clean-up bismar cache

Examples

bismar js:@noble/hashes           # vim-like pager
bismar rs:serde
bismar gem:sinatra/README.md
bismar gh:@paulmillr              # user repos
bismar gem:sinatra/lib/sinatra.rb > s.rb

bismar -l npm:micro-ftch

bismar -b js:qr > qr.js
bismar -b rs:serde > serde.cargo
bismar -bm js:qr > qr.min.js

bismar -s js:chokidar
bismar -bs npm:micro-ftch
bismar -bsm npm:micro-ftch

bismar -d js:[email protected] js:[email protected]
bismar -ds npm:readdirp@{4,5}
bismar -dbs npm:readdirp@{4,5}
bismar -dbsm npm:readdirp@{4,5}

# hint: non-terminal (non-TTY) emits DIFFERENT, machine-friendly output
bismar -d npm:micro-ftch@{1.0,1.1} | head
bismar -bsm npm:react | sort -t, -k4 -rn

Selectors & namespaces

selectors (package / ref / dir / archive):
  npm:qr, npm:[email protected], gem:sinatra, ../sinatra, ./qr.tar.bz2

namespaces ("short: long"; both versions work):
  js:   npm         py:   pypi
  jsr:  jsr         php:  packagist
  rs:   crate       gh:   github
  rb:   gem         go:   go proxy
  gitlab: gitlab

Security

flowchart LR
  B[bismar] --> W["micro-ftch: host allowlist, per redirect hop, GET/HEAD only, rate-limited, BISMAR_LOG"]
  W -->|allowed hosts, table below| R[registries]
  W x--x|refused before send| X[any other host]
  B --> N["npm subprocess (npm/jsr) --ignore-scripts --prefer-offline"]
  N -->|npm's own traffic, honors npm config| NR[npm registry]
  R --> C["$TMPDIR/bismar-* caches; removed on reboot or --clear"]
  NR --> C

• GET+HEAD only traffic: no POSTs; --no-audit removes npm’s one routine POST too.
• Host allowlist, enforced pre-send: only the origins below are reachable. Same with download URLs, except packagist (github zipballs) and pypi (pythonhosted).
• No code execution: npm runs --ignore-scripts; bundling and measuring are static esbuild work; non-JS packages are never executed or bundled.
• Inert terminal output: registry text, paths, source, diffs, errors, and CSV have controls neutralized; only bismar’s own color sequences survive.
• Bounded, link-free archives: metadata and downloads have streaming hard limits; extraction rejects traversal, links, special files, unsafe Windows names, and expansion/member/path bombs before trusting the resulting tree.
• Confined packages, verified caches: downloaded manifest paths, generated entries, and imports stay inside their install root. Private atomic caches use SHA-256 identities/digests; git pins retain full GitHub SHA-1 and GitLab SHA-1/SHA-256 commit IDs.
• Big downloads ask first: 100mb+ needs a terminal confirmation; plain refusal in scripts and CI (use BISMAR_BIG=1)
• Disposable caches: everything lives under $TMPDIR/bismar-*, OS-cleaned after reboot; bismar --clear wipes it now. Pinned versions cache until reboot, floating “latest” for 15 minutes.
• Knobs: BISMAR_LOG=file.txt logs every request, one line each; BISMAR_RPS tunes the polite request budget (0 disables); overriding a BISMAR_* base admits that origin in place of the default.

Three deps are used: esbuild and micro-ftch are pinned, and the syntax highlighter is vendored and bundled with the package, so none can update underneath a release.

License

MIT License (c) 2026 Paul Miller (https://paulmillr.com)