Free · Private · No sign-up
Compress PDF & Images Online for Free
Make your files smaller in seconds. Fast, simple, and private compression directly in your browser.
Your files stay on your device.
Everything you need to slim your files
Pick a tool. Each one runs entirely on your device.
Compress PDF
Shrink PDFs by optimising images and internal structure.
Open toolCompress JPG
Smaller JPEG photos with the MozJPEG encoder.
Open toolCompress PNG
Lossless optimisation or smart colour reduction.
Open toolCompress WebP
Compress WebP or convert images to WebP.
Open toolCompress Images
Batch-compress JPG, PNG and WebP with full control.
Open toolResize Images
Change dimensions by percentage or exact pixels.
Open toolWhy people choose SlimMyFile
No registration
Open a tool and start. No account, no email, no waiting.
Browser-based processing
Compression runs on your device using WebAssembly encoders.
No file uploads
Your documents and photos never travel to our servers.
Adjustable quality
Presets for beginners, sliders and options for full control.
Easy downloads
Download files one by one, or everything at once as a ZIP.
Mobile-friendly
Works on phones and tablets as well as on desktop.
Free basic tools
All the tools on this site are free to use.
How it works
- 1
Select your file
Drag and drop or browse. Files are opened locally by your browser.
- 2
Choose compression settings
Use a preset or fine-tune quality, size and format.
- 3
Download the result
See the real size saved, then download your smaller file.
A quick guide to file compression
How image compression works
Photos contain far more detail than the eye can see. Encoders such as MozJPEG and WebP discard detail that matters least for perception and store the rest efficiently. Reducing the pixel dimensions is often the biggest win: a 4000-pixel photo shown at 1200 pixels wastes most of its bytes.
How PDF compression works
A PDF is a container of text, fonts, vector drawings and images. Most of its size usually comes from embedded images. SlimMyFile re-encodes oversized photos, recompresses internal data streams and removes unused objects — while keeping text searchable and graphics sharp.
Lossy vs. lossless
Lossless compression rewrites data more efficiently without changing a single pixel — PNG optimisation is lossless. Lossy compression (JPEG, WebP, colour reduction) removes information to get much smaller files. At sensible settings, the difference is hard to notice.
Why local processing protects your privacy
Many online compressors upload your file to a server. SlimMyFile downloads the compression code to your browser instead, so contracts, IDs and personal photos never leave your device.
Frequently asked questions
Are my files uploaded to a server?
No. SlimMyFile loads its compression code into your browser, and your files are read and processed on your device. File contents and filenames are never sent to us or to third parties.
Do you store my files?
No. Files are held only in your browser’s memory while the page is open. They are not written to persistent browser storage, and closing or reloading the page discards them.
Can I use SlimMyFile offline?
Once a tool page and its compression engine have loaded, processing does not need a connection. The site is not a full offline app, so you need to be online to open pages.
Which formats are supported?
PDF for document compression, and JPG/JPEG, PNG and WebP images. Images can be saved as JPEG, PNG or WebP.
What is the difference between lossy and lossless?
Lossless compression keeps every pixel identical and rewrites the data more efficiently. Lossy compression removes some detail to produce much smaller files. JPEG, WebP and PNG colour reduction are lossy; PNG lossless optimisation is not.
Why is my compressed file larger than the original?
This can happen when an image was already heavily compressed, when you choose a high quality, or when converting to a less efficient format. SlimMyFile always shows the real size and keeps your original when nothing else changed.