A file size reducer is a tool that compresses files so they take up less space and are easier to upload, share, or store. It works by optimizing internal data — for example, recompressing images inside a PDF, stripping metadata, or reducing color depth in a PNG — to shrink the file without making it unusable.

Smaller files are faster to send by email, easier to upload to websites, and use less storage on your device or cloud. A file size reducer is especially useful when you hit email attachment limits, need to speed up a website, or want to save disk space on large collections of PDFs and images.

Yes. This file size reducer runs entirely in your browser using client-side processing. Your files are never uploaded to a server, which means no one else can access them. It is one of the most private ways to reduce file size online.

It depends on the compression level you choose. A file size reducer can use lossless compression — which keeps the file identical but smaller — or lossy compression for bigger savings with a slight trade-off in quality. For most PDFs and images, the default balanced setting reduces file size significantly while keeping everything looking sharp.

This online file size reducer supports PDF, PNG, JPG, SVG, BMP, and WebP. If you need to reduce file size for additional formats like HEIC, GIF, MP4, MOV, or MP3, download the TinyFast Mac app which handles all of those and more.

Results vary by file type and content. PDFs with embedded images often shrink by 50–80%. PNGs and JPGs typically reduce by 30–70%. The file size reducer shows the before and after size so you can see exactly how much space you saved.