Office files (.docx, .xlsx, .pptx) and .zip files are just ZIP containers. PackFit unzips the file, recompresses the JPEG/PNG images stored inside, drops the throwaway preview thumbnail, and rezips — all in one pass. Great for getting a document under an email attachment size limit.
The shrunk file reopens normally in Word, Excel, or PowerPoint. Filenames and formats inside are never changed, and your original file is left untouched — the shrunk copy downloads as a separate file.
Everything happens in your browser using fflate and HTML canvas. Nothing is ever uploaded — no upload queue, no account, no server.
Yes — one file per run, up to 10 MB, is free forever. Pro (one-time) unlocks batch processing, unlimited file size, and image quality and max-dimension controls.
The savings come from recompressing embedded images, so already-compressed ZIPs and files with no big images inside will shrink little.
Pro adds a per-image breakdown of what was recompressed.