linkmapviz

Minimal viewer for linker map files. Upload a .map or gzip-compressed .map.gz file to see binary size as a D3 treemap grouped by object file and symbol.

Two formats are supported, detected from the file's own contents:

| Linker | How to produce a map | | --- | --- | | wasm-ld | -Wl,-Map=output.map | | Apple ld (ld64, ld-prime) | -Wl,-map,output.map, or Xcode's LD_GENERATE_MAP_FILE=YES with LD_MAP_FILE_PATH |

The demo includes a JavaScriptKit Basic example linkmap (public/samples/javascriptkit-basic.map.gz, 19 MB → 1.2 MB gzipped).

Live demo: https://kateinoigakukun.github.io/linkmapviz/

https://github.com/user-attachments/assets/e3072cb7-a254-42b2-8b1a-c500911ca246

CLI

The linkmapviz command renders a linker map as a single, self-contained HTML file. No server needed, just open it in a browser:

npx linkmapviz output.map              # writes output.html
npx linkmapviz output.map -o report.html

Development

npm install
npm run dev

Build

npm run build         # the playground, into dist/
npm run build:report  # the report template the CLI fills in, into dist-report/
npm run build:cli     # the parser the CLI runs in Node, into dist-cli/
npm run preview

Tests

npm test          # unit tests (Vitest)
npm run test:e2e  # browser tests (Playwright)

Releasing

Bump the version, then push a matching v tag:

npm version patch   # or minor / major
git push --follow-tags

Linkmap formats

Both parsers normalise to the same shape, so everything downstream (the path tree, the treemap, the symbol drawer) is format-agnostic. parseLinkmap picks the parser; there is no setting.

Object names are taken from the path basename with a trailing .o stripped. Archive members are named after the member rather than the archive, so libFoo.a(Bar.o) reads as Bar. No language- or toolchain-specific path rewriting is applied.

wasm-ld

A column layout, one row per section and per symbol:

    Addr      Off     Size Out     In      Symbol
       -        8     6240 TYPE
       -   146bf9       20         /path/to/object.o:(symbol_name)

Apple ld

Four labelled sections. Symbols reference an object file by its index in the table above them, and a symbol's section is resolved from the address ranges in # Sections:.

# Path: /path/to/binary
# Arch: arm64
# Object files:
[  1] /path/to/foo.o
# Sections:
# Address	Size    	Segment	Section
0x100004000	0x00001000	__TEXT	__text
# Symbols:
# Address	Size    	File  Name
0x100004000	0x00000100	[  1] _$s3Foo3BarV

Symbols listed under # Dead Stripped Symbols: are excluded. The linker removed them, so counting them would overstate every total. And the Mach-O leading underscore is stripped from symbol names, which is what lets Swift's $s prefix reach the demangler.

License

MIT