Canvas API · Local JavaScript · No Server — Complete Privacy
Most online editing tools send your images to their servers for processing. That is convenient, but it means your photos — personal, professional, or confidential — transit through a third-party infrastructure. Flowfiles works differently: all processing happens entirely in your browser, on your own device. When you load a photo of a butterfly or a rose to change its color, that file never leaves your computer or phone. No image data is transmitted, stored, or analyzed by any server.
100% local processing — your images stay on your device. No account required, no file sent anywhere.
Open the No-Upload Color Replacer →When you drag an image into the tool, your browser reads it directly from your disk via the File API — with no network request. The image is then drawn into an HTML5 Canvas element in memory. The Canvas provides access to the raw data of every pixel as an array of RGBA values. All color replacement code — color distance calculations, rule application, edge smoothing — runs in JavaScript on your own processor.
The result is written into a second Canvas, displayed side by side with the original. The final download uses canvas.toBlob(), which generates the file directly in local memory and offers it for download without going through any server. The entire flow — loading, processing, export — is local to your browser.
You can verify this yourself: after loading the page once, enable airplane mode or disconnect your network. The tool continues to work normally, because the code is already loaded locally and the processing never needs the internet. This is the simplest proof that nothing is sent to any server.
Your image is read by your browser via the File API, drawn into an HTML5 Canvas in local memory, and all color replacement calculations run in JavaScript on your own processor. No data travels over a network at any point.
Yes. The tool makes no network connection involving your images. Your files are not sent to Flowfiles or any third-party service. You can verify this by using the tool in airplane mode — it works without internet.
The tool resizes images to a maximum of 1600 pixels on the longest side before processing, to maintain smooth performance. Smaller images are processed at their original size. The practical limit is the available memory of your browser.
Yes, once the page is loaded in your browser, the tool works entirely offline. Only the initial page load requires a connection to download the static resources.