File Compressor — Free, Fast & Private
MiniPx is a free file compressor that reduces image file sizes directly in your browser. Unlike server-based tools that upload your files to remote servers, MiniPx processes everything locally on your device using the Canvas API and WebAssembly. This means zero privacy risk, no account required, and instant results without waiting in upload queues.
The tool supports all major image formats: JPEG, PNG, WebP, AVIF, GIF, BMP, TIFF, and SVG. You can compress files individually or in batch — 5 files per batch on the free tier, and Pro removes that cap so an entire folder goes in at once. Each file shows before-and-after sizes with the percentage saved, and you can download compressed files individually or as a single ZIP archive.
For users who need specific file sizes (under 50KB for government forms, under 100KB for profile uploads, under 200KB for documents), MiniPx offers dedicated size-target modes. For web developers optimizing page speed, the Smart compression preset automatically balances file size against visual quality — typically achieving 50-70% reduction with no visible difference.
How file compression works
Image file compression reduces file size by removing data that humans cannot perceive. Lossy compression (JPEG, WebP, AVIF) discards subtle colour differences and high-frequency texture details that are invisible at normal viewing sizes. Lossless compression (PNG) reorganizes pixel data into more efficient patterns without removing any information. MiniPx uses a multi-pass algorithm that tries multiple quality levels and format options, then picks the smallest output that meets your quality requirements.
The three compression presets work as follows: Gentle (quality 82%) preserves maximum detail with 20-40% size reduction — ideal for photography portfolios and print-quality images. Smart (quality 65%) offers the best balance with 50-70% reduction and no visible quality loss — recommended for web use. Tiny (quality 40%) produces the smallest possible files with 75-90% reduction — best for size-constrained uploads where some quality loss is acceptable.
Why MiniPx is different from other file compressors
Most online file compressors (TinyPNG, iLoveIMG, Compressor.io) upload your images to their servers for processing. This means your photos travel across the internet, get stored on third-party infrastructure, and you have no control over what happens to them afterwards. MiniPx processes everything client-side — your files literally never leave your device. This makes it the only file compressor suitable for sensitive content like personal photos, identity documents, medical images, or confidential business materials.
Other advantages: a 200 MB per-file ceiling (many tools reject anything over 5-10 MB), no registration, and no processing queue. Since compression happens locally it is generally faster than a server-based alternative, because nothing is uploaded and downloaded again. To be exact about our own limit rather than vague: the free tier processes 5 files per batch and Pro removes that cap. There is no monthly credit or quota on either.
Where the destination has its own rules, the settings that work are different enough to be worth their own page. Presentations: PowerPoint and Google Slides, which refuses any image over 25 megapixels regardless of file size. Writing and notes: Notion and Substack. Selling: eBay, Amazon listings and property listings.
Three cases invert the usual advice and need the Gentle preset rather than Smart, because the file is evidence or a credential rather than decoration: medical records, insurance claim photographs, and job application documents. In all three, an unreadable digit costs more than a large file does.
Not every upload limit is about images: compressing a PDF works the same way in the browser, and is what most portals actually want when they ask for a document rather than a photograph.