Drop your ACO file. We'll convert it to GPL right here in your browser, your file never leaves your device.
Drop your file here
or click to pick from your device
How it works
Click the dropzone above or drag a ACO from your desktop. Files of any size, there's no upload, so there's no upload limit.
The conversion runs entirely in this tab using JavaScript and WebAssembly. Your file never touches our servers, we don't have any.
Get your GPL the moment the conversion finishes. Convert another, or close the tab.
Your file is never uploaded. The entire conversion runs in your browser using WebAssembly. We can't see what you convert because we have no server to see it.
Server converters cap free users at 1-2 GB and gate larger files behind a paid plan. Since nothing uploads, our limit is whatever your browser can handle.
No account required. No watermark on the output. No queue. Open source, every line of conversion code is public.
Formats involved
ACO is Photoshop's older binary color palette format (predates ASE). Two versions exist: v1 (color values only) and v2 (adds names). Most contemporary Photoshop users have moved to ASE for cross-Adobe-app compatibility, but ACO remains the format you get when Photoshop's swatch panel exports.
How to open
Photoshop natively. Krita, GIMP (with plugin), Affinity Photo. Convert to ASE for Illustrator/InDesign use.
GPL is GIMP's plain-text palette format. Each line: R G B Name (R/G/B as 0-255 integers). Trivially diff-able, scriptable, and human-readable, which is why open-source design tools (Inkscape, Krita) and many web color tools support GPL natively even when they don't read ASE/ACO.
How to open
GIMP, Inkscape, Krita, Aseprite, MyPaint. Plain text in any editor, generate or edit them programmatically.
Related tools
How we compare
| Feature | Ustwineconvert | CloudConvert | iLovePDF | FreeConvert | Smallpdf |
|---|---|---|---|---|---|
| Files uploaded to a server | |||||
| Free file size limit | No limit | 1 GB | 200 MB | 1 GB | 5 GB |
| Free conversions per day | Unlimited | 10/day | Limited | Limited | 2/day |
| Signup required | |||||
| Watermark on output | |||||
| Open source | |||||
| Works offline (after first load) |
Last verified May 2026 from each competitor's pricing and FAQ pages. Limits and pricing change frequently.
FAQ
Yes. No signup, no watermark, no daily file count limit. The entire engine is open source, you can read the conversion code on GitHub.
Nowhere. The conversion runs entirely in your browser using JavaScript and WebAssembly. Your file is never uploaded to our servers. We don't have any servers handling files, there's nothing for us to log, store, or accidentally leak.
Whatever your browser can hold in memory. Practically, this means a few hundred MB on most computers, significantly larger than the 1-2 GB caps that server-upload converters charge for. Very large files (multi-GB) may require closing other browser tabs first.
Photoshop swatch panel exports. Color palette sharing in open-source design workflows. The most common reason to convert is compatibility, GPL works in places where ACO doesn't, or vice versa.
Photoshop natively. Krita, GIMP (with plugin), Affinity Photo. Convert to ASE for Illustrator/InDesign use.
Once the page is loaded, the conversion itself runs entirely offline. The first time you use a tool, your browser downloads the conversion library (a one-time cache). If you reload while offline, the page won't load, but you can install the site as a Progressive Web App for full offline use.
Single file at a time for now. Batch conversion is on the roadmap, for now, drop one file, download the result, then convert the next.