A faster implementation of Electron's ASAR archive format.
This is both a library and a CLI tool.
You can install fast-asar from NPM (or your preferred package manager):
npm install fast-asarYou can use the CLI tool to extract and create ASAR archives.
npx fast-asar helpThe library exports an Asar class, which can be used to read and write ASAR archives.
For example, to extract an ASAR archive to a directory:
import { Asar } from "fast-asar";
import { readFile } from "fs/promises";
const asarBytes = await readFile("./app.asar");
const asar = new Asar(asarBytes);
await asar.extract("./app-extracted");For more information, see the API documentation.
This library can be run with Node.js and Bun.
Browser support is planned.
The following benchmarks were run with hyperfine on a 2016 MacBook Pro with a 2.9 GHz Quad-Core Intel Core i7 processor and 16 GB of RAM.
This benchmark extracts all files in the Replit Desktop app's app.asar file.
| Command | Mean [ms] | Min [ms] | Max [ms] | Relative |
|---|---|---|---|---|
./node_modules/.bin/asar extract test/ignore/app.asar test/ignore/app1 |
670.0 ± 52.6 | 614.6 | 739.4 | 1.54 ± 0.41 |
bun ./src/cli/index.ts extract test/ignore/app.asar test/ignore/app2 |
435.1 ± 110.9 | 373.7 | 632.3 | 1.00 |
Summary: fast-asar is 1.54 ± 0.41 times faster than @electron/asar.
To run this benchmark yourself, run bun run benchmark:extract.
This benchmark packs the src directory into an ASAR archive at test/ignore/src.asar.
| Command | Mean [ms] | Min [ms] | Max [ms] | Relative |
|---|---|---|---|---|
./node_modules/.bin/asar pack src test/ignore/src.asar |
154.7 ± 45.3 | 123.4 | 231.7 | 1.93 ± 0.57 |
bun ./src/cli/index.ts pack src test/ignore/src.asar |
80.0 ± 3.1 | 77.6 | 85.4 | 1.00 |
Summary: fast-asar is 1.93 ± 0.57 times faster than @electron/asar.
To run this benchmark yourself, run bun run benchmark:pack.
This benchmark lists all files in the Replit Desktop app's app.asar file.
| Command | Mean [ms] | Min [ms] | Max [ms] | Relative |
|---|---|---|---|---|
./node_modules/.bin/asar list test/ignore/app.asar |
136.0 ± 31.3 | 117.5 | 191.5 | 1.28 ± 0.30 |
bun ./src/cli/index.ts list test/ignore/app.asar |
106.0 ± 5.9 | 101.3 | 116.2 | 1.00 |
Summary: fast-asar is 1.28 ± 0.30 times faster than @electron/asar.
To run this benchmark yourself, run bun run benchmark:list.
For the tests, you must have the Replit Desktop app's app.asar file in the test/ignore directory.
You can get this file by installing the Replit Desktop app and copying the app.asar file from the installation directory.
Then, to run all tests:
bun pretest
bun test