Free Online Compress PDF
Strip metadata and rebuild PDFs to cut file size without quality loss
Try these next
For one-off compressions, the browser tool above does the job. When you're dealing with batch processing dozens of files or need granular control over image quality vs. file size tradeoffs, Adobe Acrobat gives you a lot more to work with. (We may earn a commission, at no cost to you.)
Why use Compress PDF
- Clears email attachment limits and portal upload caps without touching image quality.
- Rebuilds the PDF from scratch -- orphaned objects, stale metadata, and incremental-save padding get dropped in the process.
- One click. No quality presets, resolution sliders, or options to misconfigure.
- Before-and-after byte comparison lets you verify the savings are worth it before replacing the original.
How it works
pdf-lib parses the PDF's cross-reference table and walks the object tree from the document catalog down. Every object that no page, annotation, or outline references is flagged as orphaned and excluded from the rebuild. Duplicate stream objects (common when the same font subset is embedded multiple times across editing sessions) are detected by content hash and merged into a single reference. The cross-reference table is rewritten as a compact cross-reference stream rather than the verbose plain-text format older editors use. Metadata dictionaries are trimmed to the minimum required fields -- producer tags, editing history, and creation timestamps are stripped. The rebuilt file is serialized with pdf-lib's save(), which writes a clean byte stream free of the incremental-save padding that accumulates when a document is opened and saved repeatedly.
About this tool
Need to email a 40MB contract but the recipient's inbox caps at 25MB? Drop the PDF here and the compressor will strip out the bloat that authoring software leaves behind -- orphaned objects, redundant font subsets, verbose metadata dictionaries, and incremental-save padding. Nothing gets uploaded; your PDF stays on your machine. Files grow heavier than they need to be for predictable reasons. Every round of editing in Acrobat or Word adds objects that later become orphaned. Presentation exports embed full-resolution images even for thumbnail-sized graphics. Enterprise systems pad PDFs with compatibility layers most viewers ignore. This tool rebuilds the document from scratch, keeping only the objects each page actually references. Expect 10-40% reduction on bloated files -- those exported from PowerPoint, generated by ERP systems, or saved dozens of times during a review cycle. Already-lean PDFs will see smaller gains. A before-and-after comparison shows the exact byte difference so you can decide whether the reduction is worth keeping. The workflow is one step: upload, compress, download. No quality sliders, no presets to second-guess. Works on phones and tablets too.
How to use Compress PDF
- Drop your PDF. Drop your PDF onto the upload area or click to browse.
- Hit Compress. One click. No settings to configure.
- Check the result. Compare before-and-after file sizes, then download the lighter version.
Use cases
- Shrinking a 15MB portfolio PDF below 5MB to fit an online job application portal's upload limit.
- Compressing a 200-page case file so it clears the 25MB email attachment cap and actually reaches opposing counsel.
- Slimming down slide-heavy lecture PDFs so students on slow campus Wi-Fi can download them before class starts.
- Archiving hundreds of grant application PDFs to a shared Google Drive without blowing through storage quotas.
- Getting a bloated ERP-generated invoice package under the 10MB limit required by a client's procurement system.
Frequently Asked Questions
It parses the PDF's internal object tree, drops anything not referenced by a page (orphaned images, unused fonts, stale form fields), and rewrites the cross-reference table in compact stream format. The visible content on each page stays identical.
No. The compressor targets structural overhead, not pixel data. Images, vector graphics, and text render exactly as before.
Heavily edited or enterprise-generated PDFs with lots of metadata bloat typically shrink 10-40%. A file that's already been optimized by another tool may barely change. The before-and-after comparison tells you the exact difference before you commit to the result.
Yes, but the gains are smaller. Scanned PDFs are mostly raster image data, so there's less structural overhead to remove. You'll still save some bytes from metadata cleanup.
No hard cap. Very large files (100MB+) will take longer because the browser has to hold the entire document in memory during the rebuild.
Related Tools
Discover more free utilities to enhance your productivity.