Cuttle
Get
GPL-3.0 Open Source • Windows 10 & 11 Native

Right-click any file. Pick the format. Done.

The offline file converter Windows forgot to build. Powered by FFmpeg and proven engines directly inside File Explorer.

Download for WindowsView on GitHub
>winget install Ameya79.Cuttle

100% offline. Open source (GPL-3.0). Original file never touched.

Powered by industry-standard engines & native Windows architecture

FFmpeg
Windows 11 & 10
Pandoc
Google WebM
GitHub
Python PIL

How Cuttle Works

Beat 1: The Old Way

Still uploading private files to random websites with ad-ridden converter portals?

Beat 2: Meet Cuttle

Right-click any file in Windows Explorer. Pick the format. Done.

Beat 3: Select Format

Step 1: Right-click the file. Step 2: Pick a format from the Cuttle menu.

Beat 4: On-Device Conversion

Original file untouched. 100% offline with zero file uploads.

Beat 5: Desktop Freedom

Convert anything right from your desktop. Open source under GPL-3.0.

Architecture & Core Guarantees

Engineered for speed, privacy, and simplicity

No telemetry. No cloud queues. Just your files converted directly on your PC.

01CPU & Local Storage

Works offline

Conversions execute entirely on your CPU and local storage. No network connections are opened, and your files never leave your computer.

[LOCAL_EXECUTION]•••
02GPL-3.0 License

Open source GPL-3.0

Every line of code is public and auditable on GitHub. Free to use forever with no hidden paywalls, subscription models, or locked features.

[PUBLIC_AUDITABLE]•••
03Windows Shell COM

Right-click native

Integrates directly into the Windows 10 and 11 File Explorer context menu. Select your file, choose the format, and convert with zero app launch friction.

[EXPLORER_NATIVE]•••
04Atomic Writes

Original file stays untouched

Source files are opened in read-only mode. Converted outputs are written to temporary files and atomically renamed only when conversion passes validation.

[READONLY_SOURCE]•••
05Zero Telemetry

No uploads or accounts

Zero signups, no email verification, no file queues, and no arbitrary file size caps. Your private documents, video clips, and photos remain strictly private.

[NO_ACCOUNTS_OR_QUEUES]•••
06FFmpeg & Pandoc Core

Powered by FFmpeg and proven engines

Under the hood, Cuttle routes tasks to industry-standard engines including FFmpeg, Pandoc, and Pillow with optimized presets for maximum speed.

[OPTIMIZED_PRESETS]•••

Why on-device beats web converters

A factual look at converting files on your own PC versus uploading to third-party web services.

Online web converters

Typical browser-based file conversion tools relying on cloud upload infrastructure.

  • File privacyFile bytes uploaded to remote cloud servers
  • Conversion speedLimited by your upload and download bandwidth
  • File size limitsFrequently capped at 50 MB to 100 MB on free tiers
  • User interfaceAd banners, queue timers, and misleading download buttons
  • Original file safetyStored temporarily on unknown third-party servers
  • Cost and licensingRecurring subscription plans or ad-supported models

Cuttle (On-Device)

Local Windows native utility operating directly on your local system resources.

  • File privacy100% local. Files never leave your drive
  • Conversion speedDirect SSD read/write speeds on your hardware
  • File size limitsUnlimited. Convert large video files without restrictions
  • User interfaceNative Windows Explorer right-click context menu
  • Original file safetyOpened strictly read-only; new file saved alongside
  • Cost and licensingFree and open source forever under GNU GPL-3.0

Supported formats & fidelity badges

Every conversion item in the right-click menu displays transparent fidelity labels so you always know what to expect.

MP4toMP3
Lossy

Extract clean audio track from video without recoding delays.

AudioConfirmed
MP4toWEBM
Lossy

Transcode video to open WebM format using FFmpeg libvpx.

VideoConfirmed
MP4toGIF
Lossy

Render animated clip with custom 256-color palette optimization.

VideoConfirmed
WAVtoMP3
Lossy

Compress uncompressed audio to high-bitrate MP3.

AudioConfirmed
PDFtoDOCX
Best effort

Reflow PDF pages into editable Word document structure.

DocumentPending maintainer
DOCXtoPDF
Lossless

Export office documents directly using headless native renderer.

DocumentPending maintainer
HEICtoJPG
Lossy

Convert Apple camera photos into universally viewable JPEG.

ImagePending maintainer
PNGtoWEBP
Lossless

Modern web image format with lossless compression savings.

ImagePending maintainer
MDtoDOCX
Lossless

Markdown to Word format preserving semantic AST structure.

DocumentPending maintainer
LosslessBit-perfect data preservation
LossyPerceptually transparent encoding
Best effortComplex structural reflow
Engineering Documentation Hub

Built on verified technical specs

Inspect our system specifications, quality models, and empirical benchmarks directly in the repository.

Core Specdocs/SPEC.md

Architecture Specification

The complete technical design document covering the four-phase conversion lifecycle, atomic file writes, Named Pipes IPC, and strict offline sandbox boundaries.

  • ›Sub-20ms cold launcher startup via Windows Named Pipes
  • ›Atomic rename guarantees source files are never altered
  • ›Zero-network engine sandbox enforced by static audit
Read on GitHub
GPL-3.0
Quality Guaranteesdocs/quality.md

Quality Transparency Model

Mathematical and perceptual fidelity standards. Every format pair is explicitly categorized so users know exactly what to expect before converting.

  • ›Lossless: Bit-for-bit container remuxing and Pandoc AST
  • ›Lossy: Tuned acoustic and perceptual presets (e.g. LAME VBR)
  • ›Best Effort: Heuristic tabular layout reconstruction for PDFs
Read on GitHub
GPL-3.0
Verified Metricsdocs/BENCHMARKS.md

Empirical Benchmarks

Measured on-device throughput, CPU/RAM utilization profiles, and comparison metrics against cloud upload-and-download overhead.

  • ›SSD read/write saturation on large 4K video transcoding
  • ›Sub-100ms processing for markdown and document formats
  • ›393 continuous integration tests validating speed & accuracy
Read on GitHubView Dedicated Page →
GPL-3.0
Shell Architecturedocs/dev-windows-shell.md

Windows Shell Integration

How Cuttle integrates into Windows 10 and 11 File Explorer without shell extensions or fragile registry hacks.

  • ›Windows 11 sparse package registration via MSIX manifest
  • ›COM IExplorerCommand dynamic cascade menu implementation
  • ›Clean, zero-residual uninstallation via cuttle uninstall
Read on GitHub
GPL-3.0
SPEC Part 2.4 • IPC PIPELINE
Native Windows IPC Pipeline

How sub-20ms instant right-click launches work

When you click a format in File Explorer, the lightweight Cuttle launcher does not spin up a heavy runtime. It connects to a persistent local worker over Windows Named Pipes (\\.\pipe\cuttle-worker), passes the file handle, and yields control instantly.

// Zero-Collision Atomic Renaming
input: sample.mp4
→ write: sample.cuttle-part.mp3
✓ checksum validation: PASS
→ rename: sample (converted).mp3
Open Source Development

Contribute to Cuttle

Licensed under GNU GPL-3.0. Developed openly on GitHub with strict safety invariants, pure offline design, and declarative registry architecture.

Developer Workflow

STEP 01

Clone & sync environment with uv

Cuttle is built with Python 3.12 and uses Astral uv for ultra-fast dependency management.

> git clone https://github.com/Ameya79/cuttle.git && cd cuttle && uv sync
STEP 02

Run the full test suite

393 comprehensive unit and integration tests ensure conversion fidelity and engine safety.

> uv run pytest
STEP 03

Lint and verify strict types

Strict type enforcement with MyPy and instant linting with Ruff maintain code quality.

> uv run ruff check . && uv run mypy cuttle/engine
STEP 04

Run local engine health diagnostics

Verifies that local FFmpeg, Pandoc, and soffice binaries meet required version minimums.

> uv run cuttle doctor

Declarative Registry

cuttle/registry/video_extract.tomlDeclarative TOML

Adding a new format pair requires 0 imperative boilerplate. Simply drop a TOML spec into the registry:

[[conversions]]
id = "mp4_to_mp3"
input = "mp4"
output = "mp3"
engine = "ffmpeg"
quality = "lossy"
args = ["-vn", "-c:a", "libmp3lame", "-q:a", "2"]
Core Invariants
Never use shell=True in process execution
Engine makes 0 network socket or HTTP requests
Source files are opened strictly in read-only mode

Ready to submit a PR?

We welcome contributions for additional format registrations, shell optimizations, and translation packs.

Good First IssuesGitHub

Frequently asked questions

Direct answers on privacy, engine architecture, and licensing.

Is Cuttle really 100% offline?

Yes. Cuttle runs entirely on your local machine using embedded open-source engines like FFmpeg. It makes zero network calls, has no telemetry or tracking, and never sends your file bytes or metadata anywhere.

Is Cuttle free to use?

Yes. Cuttle is 100% free and licensed under the GNU General Public License v3.0 (GPL-3.0). There are no paid subscriptions, no conversion quotas, and no ads.

Does Cuttle change, overwrite, or delete my original file?

Never. The original file is opened strictly in read-only mode. Cuttle writes converted files to a temporary extension (.cuttle-part) and atomically renames only upon complete success. If a file with the destination name already exists, Cuttle safely appends a sequential counter (e.g. sample (converted).mp3) so no existing file is ever overwritten.

Which versions of Windows are supported?

Cuttle is built natively for 64-bit Windows 10 and Windows 11. On Windows 11, it integrates directly into the top-level modern context menu via an IExplorerCommand sparse package so you do not have to click 'Show more options'.

How do I install Cuttle?

You can install via Windows Package Manager using 'winget install Ameya79.Cuttle', download the standalone installer (.exe), or unpack the portable zero-install archive (.zip). Installation runs in your local user directory without requiring administrator / UAC elevation.

How do I report bugs or request new format support?

Cuttle is developed in the open on GitHub. You can file bug reports, submit conversion logs, or open feature requests directly at https://github.com/Ameya79/cuttle/issues.

What license is Cuttle released under?

Cuttle is licensed under the GNU General Public License v3.0 (GPL-3.0). You have the freedom to inspect the source code, build it locally, modify it, and distribute your own builds under the same terms.

Windows 10 & 11 (64-bit)

Convert anything.
Right from your desktop.

No cloud uploads. No ad networks. No subscription fees. Just fast native conversions powered by FFmpeg.

Download for WindowsDownload Portable .ZIPSource Code (GPL-3.0)
>winget install Ameya79.Cuttle