About SlimMyFile

Our approach

Compressing a file should not require trusting a stranger’s server with your documents. SlimMyFile runs professional-grade encoders directly in your browser using WebAssembly and Web Workers, so your files stay on your device from start to finish.

Who SlimMyFile is for

Anyone who needs a smaller file quickly: students submitting assignments, people uploading documents to application or government portals, small businesses emailing invoices, and website owners preparing images. There is nothing to install and no account to create.

Honesty first

We show real file sizes and real savings, calculated from the actual output. When a file cannot be made meaningfully smaller, we tell you and keep the original. We do not fake progress bars or promise unrealistic results.

Built on open technology

SlimMyFile is built on well-known open-source projects, including:

• MozJPEG (JPEG encoding), libwebp (WebP) and OxiPNG (PNG), via the jSquash project
• pdf-lib for PDF structure optimisation and PDF.js for previews and page rendering
• image-q for PNG colour quantisation, and React for the interface

What SlimMyFile cannot do

Because everything runs in your browser, some things are out of reach. SlimMyFile cannot open password-protected PDFs, subset fonts, recognise text in scans (OCR) or guarantee a particular file size. Very large files are limited by your device’s memory. When a file cannot be made meaningfully smaller, the tools say so and offer your original.

Free to use

The tools are free. To cover costs, the site may show clearly labelled advertising. Ads never replace or imitate download buttons, and advertising scripts never receive your files.