PDF Compressor — Reduce PDF Size Free

PDF file size matters the moment you try to email a document and hit the attachment limit, or upload it to a portal with a 5 MB cap. PDF Compressor re-serialises the document through a clean pass that removes redundant metadata strings, rebuilds the cross-reference table in a compressed form, and packs the object graph into deflate-compressed streams. For PDFs exported from Microsoft Office, a browser print-to-PDF, or a LaTeX build, this typically saves 10 to 40 percent without touching a single pixel of content.

Drop the file, choose your options, and click Compress PDF. Everything runs in your browser tab — the file is never uploaded to a server, and the compressed result is assembled in memory and handed back as a download.

Getting Your First Compressed File

1. Drop a PDF onto the drop zone or click to browse. The tool reads the first 4 bytes to confirm a valid %PDF header and rejects anything that fails that check with the message “This file does not look like a valid PDF (missing %PDF header)."
2. Leave both options checked for maximum compression. The Strip metadata checkbox removes the title, author, subject, keywords, producer, and creator strings from the document dictionary. The compressed object streams checkbox is the bigger lever: it packs the internal object graph into deflate streams, a feature available since PDF 1.5 (Acrobat 6, 2003).
3. Click Compress PDF. The Original, Compressed, and Saved figures appear side by side. A warm amber notice appears if savings are below 3 percent, explaining why a near-zero result is not a bug.
4. Click Download to save the result as filename-compressed.pdf. Click New fileto process another document without reloading the page.

How Big a PDF This Can Handle

• 100 MB hard limit. Files above 100 MB are rejected immediately with the message “File is X MB — the limit is 100 MB." The limit matches the rest of the PDF tool family and reflects what comfortably fits in a browser tab’s memory budget on a typical device.
• Image-heavy PDFs save very little. Scanned documents store each page as a JPEG or JFIF image stream. Those streams are already compressed at capture time, and re-compressing them requires a full decode-encode cycle with a native image codec. Browsers do not expose that path, so the saving on a scan is typically under 1 percent. The tool flags this with the amber notice when savings fall below 3 percent.
• Password-protected PDFs are rejected. If pdf-lib detects encryption, the tool shows “This PDF is password-protected. Remove the password before compressing it." Remove the password in your PDF reader first, then retry.
• Object-stream compression requires PDF 1.5. Disabling that option produces a PDF readable by very old viewers (Acrobat 5 and earlier) at the cost of a larger file. Nearly all modern readers support PDF 1.5, so leaving it enabled is correct for virtually every use case.