Multi-Converter is a free and open source tool to convert your files directly on your computer.
Documents, images, audio and video — no account, no cloud, no file upload to any server.
- Why use Multi-Converter?
- Download
- Overview
- Supported Formats
- Privacy
- Maximum Quality Extension
- Licenses
- Legal Notice
- Development
- Contributing
- Code of Conduct
- Security
- Star History
| Key point | What it means for you |
|---|---|
| 🆓 Free and open source | Use Multi-Converter freely and browse its source code. |
| 🔒 Local and private | Your files stay on your computer throughout the conversion. |
| 🔄 Multi-format | Documents, images, audio and video — all handled in a single app. |
| ⚡ Optional advanced mode | The Maximum Quality extension adds specialized engines for complex conversions. |
| System | Status | Download |
|---|---|---|
| 🪟 Windows x64 | ✅ Available | .exe |
| 🍎 macOS | 🚧 In development | Not yet available |
| 🐧 Linux | 📋 Planned | Not yet available |
Multi-Converter detects the formats listed below and offers compatible conversions based on the available engines.
| Category | Recognized formats |
|---|---|
| 📄 Documents & text | PDF, DOCX, TXT/LOG, HTML/HTM, CSV, JSON, ODT, RTF, Markdown/MD, EPUB, XML |
| 🖼️ Images | PNG, JPEG/JPG, SVG, WebP, TIFF/TIF, BMP, ICO |
| 🎵 Audio | MP3, AAC/M4A, FLAC, WAV, OGG/OGA, WMA, OPUS, AIFF/AIF, ALAC, AC3, MP2, AMR, AU/SND, CAF |
| 🎬 Video | MP4/M4V, MKV, WebM, MOV, AVI, WMV, 3GP/3G2, MTS/M2TS, MPEG-2/MPG/MPEG, OGV |
Note Some formats may be recognized without supporting every possible conversion to every other format. The options shown in the app depend on the source file and the available engines.
Conversions run on your machine. An internet connection may be required to download the app, install an update, or retrieve the optional Maximum Quality extension, but Multi-Converter never sends your files to the cloud.
The Maximum Quality extension downloads third-party engines to improve Office, PDF, Markdown/HTML/EPUB and advanced image conversions.
Full Windows x64 installation as declared in the manifest, sizes rounded:
| Engine | Mainly used for | Download | Once installed | License |
|---|---|---|---|---|
| PDFium | PDF to image rendering | 5.6 MB | 13.1 MB | BSD-3-Clause |
| LibreOffice headless | Accurate Office and PDF conversions | 483.8 MB | 1.51 GB | MPL-2.0 |
| Pandoc | Markdown, HTML, EPUB, DOCX | 40.7 MB | 231.1 MB | GPL-2.0-or-later |
| libvips | Advanced images | 10.8 MB | 28.5 MB | LGPL-2.1-or-later |
| Total | Full extension | 540.9 MB | 1.79 GB | Multiple licenses |
Note You can keep only the base conversions if you don't need these advanced engines.
Multi-Converter's code is licensed under Apache 2.0. See LICENSE.
Multi-Converter uses third-party conversion engines that retain their own licenses, notices and redistribution conditions. They do not change license because you use them through Multi-Converter.
Key points:
- Multi-Converter itself is licensed under Apache 2.0.
- Third-party engines remain separate software with their own licenses.
- The Windows x64 V1 release bundles FFmpeg and ffprobe
8.1.1-essentials_build-www.gyan.dev, built with--enable-gpl: the bundled executables are treated as third-party software covered by the GPL in this distribution. - The Maximum Quality extension may install PDFium, LibreOffice, Pandoc and libvips, each under their own license.
See NOTICE and docs/THIRD_PARTY_ENGINES.md for details.
This documentation is not legal advice. Release maintainers must verify the exact obligations of the binaries and third-party engines they distribute.
This section is for anyone who wants to run the project locally, fix a bug, suggest an improvement, or explore the code. Releases, installers, engine archives and release notes are prepared by the project maintainers.
| Layer | Technology |
|---|---|
| Desktop application | Tauri 2 |
| UI | React + TypeScript |
| Backend | Rust + Cargo |
| Frontend build | Vite |
| Internal scripts | Node.js |
- Windows x64 for developing the currently supported version.
- Node.js
>=24 <25and npm>=11 <12. - Rust and Cargo.
- The Tauri prerequisites for Windows.
git clone https://github.com/Amix29/Multi-Converter.git
cd Multi-Converter
npm install# Full desktop app: Tauri, real conversions, sidecars
npm start
# Equivalent command
npm run tauri:dev
npm run devonly starts the Vite frontend with a simulated API. To test real conversions, sidecars, the Tauri runtime or file system access, usenpm startornpm run tauri:dev.
Recommended checks before a pull request:
npm run check
npm run test:rust
npm run test:pdfium-wrappernpm run check covers installer asset generation, base engine validation, embedded manifest validation, i18n validation, TypeScript typechecking and engine packaging validation.
Targeted commands useful during development:
npm run typecheck
npm run validate:i18n
npm run validate:embedded-manifest
npm run validate:bundled-base-engines
npm run validate:enginesBuild:
npm run build
npm run tauri:buildRust formatting and linting:
npm run fmt:rust:check
npm run clippy:rust
npm run clippy:pdfium-wrapperOn Windows PowerShell, direct Cargo commands can also use a temporary build folder:
cargo fmt --manifest-path src-tauri/Cargo.toml
cargo test --manifest-path src-tauri/Cargo.toml --target-dir "$env:TEMP\mc-cargo-target-engine-registry"npm run tauri:dev and npm run tauri:build use a temporary CARGO_TARGET_DIR to avoid stale Tauri artifacts in src-tauri/target.
src/ React UI
src/i18n/ UI translations
src-tauri/ Tauri/Rust backend
src-tauri/binaries/ Base sidecars bundled for Windows x64
src-tauri/engines-manifest.json
docs/ License, security and third-party engine documentation
tools/ Engine technical configuration
scripts/ Build, validation and maintenance scripts
Generated folders (dist, node_modules, build caches, local engine sources, engine archives, test results) must not be committed.
Multi-Converter works with two engine tiers:
| Tier | Role | Distribution |
|---|---|---|
| Base | Common conversions available with the app | Integrated engines or bundled sidecars |
| Maximum Quality | More accurate or more advanced conversions | Optional archives distributed separately |
The Windows x64 base engines ffmpeg and ffprobe are bundled in src-tauri/binaries and validated before each build.
Restore and validate the base engines:
npm run prepare:bundled-base-engines
npm run validate:bundled-base-enginesTo work locally on engine scripts, place temporary sources under:
engine-sources/windows-x64/<engineId>/
Important Do not commit generated archives, local engine sources, release checksums or engine version changes without explicit approval from a maintainer.
See tools/ENGINE_PACKAGING.md and docs/THIRD_PARTY_ENGINES.md for technical context.
Contributions are welcome. Read CONTRIBUTING.md before opening a pull request.
Expected contributions include bug fixes, optimizations, UI improvements, translations, tests and feature suggestions. Before submitting a change, run the checks relevant to the area you modified.
Multi-Converter is an open source project. Everyone is expected to participate with respect, clarity and good faith.
- Be respectful and welcoming to contributors of all experience levels.
- Keep discussions constructive, technical when possible, and focused on the project.
- When reporting a bug, include what happened, what you expected, and how to reproduce it.
- When reviewing code, focus on the change, the behavior, and concrete improvements.
- Harassment, insults, discriminatory language, personal attacks or threats.
- Spam, repeated off-topic messages, advertising, or low-effort comments that disrupt the project.
- Deliberately misleading reports, hostile reviews, or behavior intended to waste maintainer time.
- Sharing private information without permission.
Maintainers may edit, hide or remove comments, close discussions, or block users when behavior harms the project or its contributors.
To report a vulnerability or security issue, open a GitHub issue. See SECURITY.md for scope and what information to include.