0.2.0 • Published yesterday

@catlabtech/webcvt-archive-zip

Licence

MIT

Version

0.2.0

Deps

Size

439 kB

Vulns

Weekly

Summary Dependency Versions

webcvt

Browser-first, hardware-accelerated file conversion library. Convert anything in the browser, no upload required.

webcvt — convert files in your browser. No upload. Hardware-accelerated.

v0.1.0 is on npm (@catlabtech/webcvt-*@0.1.0, 2026-04-23). v0.2.0 is prepared and pending publish — it adds the modern image codecs, the full container second passes, and the Phase 7–9 packages (email, EPUB, font, doc-pdf, comic, backend-native, api-server). The tag-triggered release workflow publishes it once the NPM_TOKEN secret is set.

34 packages shipped across Phases 1–9 (@catlabtech/webcvt-core + 11 image/codec, 9 container, 2 data/subtitle, 1 email, 1 ebook, 1 font, 1 pdf, 1 comic, 1 CLI, 1 HTTP API, 4 ancillary)
4,986 tests passing; CI green
Phase 3 (core containers, second-pass Minus): complete — classic + fragmented MP4, multi-track, avc/hevc/vp9/av1 video, edit lists, iTunes metadata
Phase 4 (image, animation, archive, data-text): complete (5/5)
Phase 4.5 (deferred-format roll-up): 11 shipped — image: TIFF, TGA, XBM, PCX, XPM, ICNS; data-text: JSONL, TOML, FWF, XML, YAML
Phase 5 (launch prep): @catlabtech/webcvt-cli, @catlabtech/webcvt-backend-wasm, apps/playground, apps/docs, and the examples/ are all shipped; v0.1.0 published to npm 2026-04-23
Phases 6–9 (modern codecs, container second passes, email/EPUB/font/PDF/comic, native + HTTP backends): complete on main, prepared as v0.2.0 — pending the npm publish

See plan.md for the full project plan, CHANGELOG.md for release notes, and CONTRIBUTING.md for how to contribute or resume work.

Try the live demo: webcvt.pages.dev — drag a file, pick a format, download in-browser.

What is it

A modular TypeScript library that converts files in the browser, using WebCodecs for hardware acceleration and ffmpeg.wasm only as a legacy fallback. Same code runs in Node.js and Cloudflare Workers.

Target: match Transmute.sh's 200+ formats and 2,000+ conversion pairs, but as a tree-shakable browser library instead of a Docker server.

Browser requirements

Pure-JS/Canvas conversions (most images, subtitles, data-text, archives) work in any modern browser with no special setup.
Hardware-accelerated audio/video paths use WebCodecs where available.
WASM backends that use threads / SharedArrayBuffer require the page to be cross-origin isolated — serve it with Cross-Origin-Opener-Policy: same-origin and Cross-Origin-Embedder-Policy: require-corp (see the playground's _headers).

Competitive positioning

	ffmpeg.wasm	Transmute	Mediabunny	webcvt
Mode	browser	server (Docker)	browser	browser-first
Bundle	30 MB	N/A	~50 KB	5–500 KB (modular)
HW accel		native
TS-native
Modular
Scope	AV only	200+ formats	AV only	200+ formats

Packages

Live list grows as Phases complete. See plan.md §3 for the full roadmap.

Foundation

@catlabtech/webcvt-core — public API, types, format detector, backend registry, capability probe
@catlabtech/webcvt-codec-webcodecs — hardware-accelerated encode/decode adapter
@catlabtech/webcvt-test-utils — shared test fixtures + byte helpers
@catlabtech/webcvt-backend-wasm — ffmpeg.wasm fallback (lazy-loaded; ~203 MIME pairs)
@catlabtech/webcvt-backend-native — Node-only server escape hatch: spawns ffmpeg/pandoc/libreoffice/ghostscript when installed (no shell; safe argv)

Audio + video containers

@catlabtech/webcvt-container-wav — RIFF/WAV
@catlabtech/webcvt-container-mp3 — MPEG-1/2/2.5 Layer III + ID3v2/v1 + Xing/LAME
@catlabtech/webcvt-container-flac — FLAC (native)
@catlabtech/webcvt-container-ogg — Ogg (Vorbis, Opus)
@catlabtech/webcvt-container-aac — AAC ADTS
@catlabtech/webcvt-container-mp4 — M4A / MP4 (classic + fragmented; multi-track; avc1/avc3/hev1/hvc1/vp09/av01 + AAC; edit lists + iTunes metadata; sidx/mfra + CENC/DRM signalling)
@catlabtech/webcvt-container-webm — WebM (VP8/VP9/AV1 + Opus/Vorbis; multi-track)
@catlabtech/webcvt-container-mkv — Matroska (AVC/HEVC/VP9/AV1 + AAC/FLAC/Opus/Vorbis; multi-track + subtitle tracks + Chapters/Tags)
@catlabtech/webcvt-container-ts — MPEG-TS / HLS + M2TS (H.264 + AAC ADTS; multi-program)
@catlabtech/webcvt-ebml — shared EBML primitives (RFC 8794)

Images

@catlabtech/webcvt-image-canvas — PNG/JPG/WebP/BMP/ICO via Canvas API
@catlabtech/webcvt-image-svg — SVG parse + Canvas rasterize (with aggressive security gates)
@catlabtech/webcvt-image-animation — GIF + APNG + animated WebP
@catlabtech/webcvt-image-legacy — PBM/PGM/PPM/PFM/QOI + TIFF + TGA + XBM + PCX + XPM + ICNS
@catlabtech/webcvt-image-jsquash-avif — AVIF encode/decode via @jsquash/avif (libavif WASM)
@catlabtech/webcvt-image-jsquash-jxl — JPEG XL encode/decode via @jsquash/jxl (libjxl WASM, royalty-free)
@catlabtech/webcvt-image-jsquash-mozjpeg — smaller JPEGs via @jsquash/jpeg (MozJPEG WASM)
@catlabtech/webcvt-image-jsquash-oxipng — lossless PNG optimise via @jsquash/oxipng (OxiPNG WASM)
@catlabtech/webcvt-image-heic — HEIC/HEIF decode (iPhone photos → PNG/JPG/WebP) via libheif-js (libheif WASM)
@catlabtech/webcvt-image-pdf — wrap an image into a one-page PDF (clean-room writer, zero deps)

Archives + data + subtitles

@catlabtech/webcvt-archive-zip — ZIP + POSIX ustar TAR + gzip
@catlabtech/webcvt-data-text — JSON + JSONL + CSV + TSV + INI + ENV + TOML + FWF + XML + YAML
@catlabtech/webcvt-subtitle — SRT/VTT/ASS/SSA/SUB/MPL

Email + Ebook + Font

@catlabtech/webcvt-email — EML (RFC 5322 + MIME) parser → text / JSON (self-written, zero deps; multipart, base64/QP, RFC 2047 encoded-words)
@catlabtech/webcvt-epub — read-only EPUB (OCF + OPF) → text / HTML / JSON; composes archive-zip + data-text (no new parsing surface)
@catlabtech/webcvt-font — sfnt (TTF/OTF) WOFF 1.0 container repackaging (self-written, zero deps; recomputes checksums; WOFF2 deferred)
@catlabtech/webcvt-doc-pdf — clean-room multi-page image→PDF writer (imagesToPdf) + structural PDF read (page count + metadata); self-written, no pdfjs/pdf-lib
@catlabtech/webcvt-comic — comic archives: CBZ → PDF (composes archive-zip + doc-pdf); CBR/CB7 detected, decode deferred (needs RAR/7z wasm)

CLI + HTTP API

@catlabtech/webcvt-cli — npx webcvt in out Node CLI with optional-dep backend loader
@catlabtech/webcvt-api-server — createApiServer() Hono app (/convert, /formats, /health) for Node/Bun/Deno/Cloudflare Workers

Planned

See plan.md §6 Roadmap. Phases 1–9 are complete on main and prepared as v0.2.0 (pending publish). What remains is the irreducible third-party-wasm-dep tier — MOBI/AZW ebooks, SQLite, Parquet/Arrow, legacy-image wasm (PSD/JP2/…), and RAR/7z comic decode — each shipping behind a lazy optional dependency as demand warrants.

Quickstart

Install

Install only the packages you need — the browser bundle stays in the 5–500 KB range instead of ffmpeg.wasm's ~30 MB.

# Images in the browser:
npm install @catlabtech/webcvt-core @catlabtech/webcvt-image-canvas
# …or just MP3:
npm install @catlabtech/webcvt-core @catlabtech/webcvt-container-mp3

Pre-release: packages publish to npm with the v0.1.0 release. Until then, use the workspace from a clone (see Development) or the live demo.

See the full supported-formats matrix.

Try it in the browser

apps/playground — drag-drop any supported file, pick a target format, download the result. Zero network requests. Or use the hosted demo at webcvt.pages.dev.

Use it in Node.js

// Low-level parse/serialize API (text formats — no setup needed)
import { parseSrt, serializeVtt } from '@catlabtech/webcvt-subtitle';
const vtt = serializeVtt(parseSrt(srtString));

// High-level convert() API (binary formats — browser or Node)
import { convert, defaultRegistry } from '@catlabtech/webcvt-core';
import { CanvasBackend } from '@catlabtech/webcvt-image-canvas';
defaultRegistry.register(new CanvasBackend());
const result = await convert(pngBlob, { format: 'webp' });

Working examples in examples/.

Development

pnpm install
pnpm build        # build all packages
pnpm test         # run all tests
pnpm typecheck
pnpm lint