Compress and convert images locally with drag and drop

Make large image files small — on your computer, with drag & drop. Optionally convert formats or set a max width/height. Local, fast, private, free, and open source.

Drop your images. DropSlim crunches the numbers. Done. Everything stays on your machine — no account, no server.

Why DropSlim

• Drag & drop — drop files or folders on the window; whole folders are processed recursively
• Small and fast — lightweight app, fast compression; built with imagequant, oxipng, zenjpeg, OXVG, gifsicle, WebP, and AVIF encoders
• Runs offline — no internet required; compression runs entirely on your computer
• Privacy — no upload, no tracking; your images never leave your machine
• Batch processing — hundreds of files in one go; new file alongside the original, or replace in place
• Optional max width / height — set pixel limits in settings; shrink oversized JPEG, PNG, WebP, and AVIF while keeping aspect ratio
• Optional output format — convert JPEG, PNG, WebP, and AVIF in settings, or keep the original; HEIC converts on macOS; GIF and SVG stay as they are
• Common formats — PNG, JPEG, GIF, SVG, WebP, and AVIF. HEIC on macOS only
• Open with DropSlim (macOS) — right-click an image in Finder → Open With → DropSlim
• Review results in a simple list and reveal outputs in Finder or File Explorer
• Languages — English, German, French, Spanish, Italian, Japanese, Brazilian Portuguese
• Open source — MIT

Where the optimized file is saved depends on your settings

• .min suffix on (default): writes a new file next to the original, e.g. photo.png → photo.min.png. The source file stays untouched.
• .min suffix off: overwrites the original in place when saving in the same folder and minified subfolder is off. With the subfolder on, the optimized file goes into minified/ under the original filename and the source stays untouched.
• minified subfolder: saves into a minified/ folder (with or without .min, depending on the suffix setting).
• Custom save folder: turn off Save optimized files in same folder in Settings — Choose folder appears; click Open to pick a destination.

Install (macOS)

Requires macOS 11 (Big Sur) or later and an Apple Silicon Mac (M1 or newer).

1. Download DropSlim_*.dmg from GitHub Releases.
2. Open the DMG and drag DropSlim to Applications.
3. Open DropSlim from Applications.

Intel Mac? Use Image Shrinker — same idea, native on Intel Macs.

CLI (macOS)

Command-line tool for batch compression — same engine as the app, no GUI. Apple Silicon only (aarch64).

brew tap onza/tap
brew install dropslim
dropslim compress photo.png images/

Or download dropslim-cli_*_aarch64.tar.gz from GitHub Releases.

Run dropslim compress --help for options (output folder, format, max dimensions, JSON output).

Install (Windows)

Requires Windows 10 or later (64-bit).

1. Download DropSlim_*_x64-setup.exe from GitHub Releases.
2. If your browser blocks the download, choose Keep or Keep anyway.
3. Run the installer.
4. If Microsoft Defender SmartScreen shows "Windows protected your PC":
   • Click More info
   • Click Run anyway
5. Follow the setup wizard and start DropSlim from the Start menu or desktop shortcut.

Linux (planned)

A Linux version is planned but not released yet. Work is happening on the feature/linux branch, where CI already builds an AppImage (x86_64). For now it is on hold because of limited testing capacity. If you'd like to help test, please open an issue.

Translations

UI translations were generated with AI and may contain errors or awkward wording. Corrections are welcome — if you spot a mistake, please open an issue or submit a pull request with an updated string in ui/i18n/locales/.

A Frustrating Side Note

DropSlim is open source and free. Nevertheless, it appears that on both major desktop platforms, it costs developers money to allow users to simply download, install and open an app without any further hassle.

On macOS, Apple requires a paid Developer Program (99 EUR per year). On top of that: identity verification with a wait time of 5 days, certificate signing requests, Developer ID certificates, app-specific passwords, authorizations, and a registration process that feels like the administration from "Asterix Conquers Rome" digitized the A38 pass to make breathing fresh air subject to approval. This project covers that fee, so Mac users get a normal install.

On Windows, SmartScreen treats unsigned installers as suspicious. A commercial code-signing certificate (roughly 100+ EUR per year, from a certificate authority or cloud signing service) is the paid entry ticket to a smoother path; even then, reputation builds slowly and rarely helps a small open-source project. This project does not pay for Windows signing — use More info → Run anyway (steps above). The installer is still safe if you download it from this repository or the project website.

None of this makes the app any better. It only buys a smoother install experience. If you know a legitimate way around either gate without compromising security, I’d be happy to hear from you :)

Credits

Inspired by Image Shrinker (CC0-1.0) by Stefan Schulz-Lauterbach.

License

MIT

Copyright (C) 2026-present, Martin Farkas.