PDF Compressor

What Does This Tool Do?

This PDF compressor reduces the file size of a PDF by re-encoding internal streams, stripping metadata, and optionally removing annotations. The result is a leaner PDF that downloads faster, emails more easily, and takes up less disk space.

How to Use This Tool

• Upload a PDF — drag and drop, or click to browse.
• Choose a compression level — Low, Medium, High, or Extreme.
• Toggle advanced options — strip metadata, optimize streams, remove annotations, linearize.
• Click "Compress PDF" — the compressed file downloads automatically.
• Or click "Analyze PDF" — see the file structure without compressing.

Compression Levels Explained

• Low — light optimization. Keeps all metadata and content intact. Best when you want a small size reduction without any risk of quality loss.
• Medium (recommended) — re-encodes streams with standard compression. Good balance of size reduction and quality retention.
• High — more aggressive stream re-encoding plus metadata stripping. May show subtle quality changes on complex documents.
• Extreme — maximum compression. Strips all non-essential data, re-encodes aggressively, and may reduce image quality if images are embedded.

What Gets Compressed

• Stream re-encoding — internal PDF streams (content, fonts, images) are re-compressed using Deflate.
• Metadata removal — author, title, subject, keywords, and creation/modification dates are stripped when enabled.
• Annotation removal — comments, highlights, form field values, and other annotations are removed when enabled.
• Object stream consolidation — multiple related PDF objects are combined into a single compressed stream.
• Linearization — reorders the file so the first page can render before the whole file is downloaded.

What Doesn't Get Compressed (Much)

• Embedded images — the tool cannot re-encode image data (that would require image processing libraries). Large images will still dominate file size.
• Embedded fonts — fonts are preserved, though their streams may be re-compressed.
• Vector graphics — paths and shapes are preserved as-is.

How Much Can You Save?

Actual savings depend heavily on the PDF's original encoding:

• Already-optimized PDFs — 0–5% savings. These are typically PDFs exported from modern tools with compression enabled.
• Uncompressed PDFs — 20–50% savings. Some older generators don't compress streams.
• PDFs with redundant metadata — 5–15% savings from stripping metadata and annotations.
• PDFs with large embedded images — limited savings; images dominate file size.

When This Tool Helps Most

• Email attachments — PDFs with verbose metadata and uncompressed streams.
• Old documents — PDFs from scanners and older tools that don't optimize.
• Batch distribution — cleaning up PDFs before sending to many recipients.
• Archival — reducing storage footprint for text-heavy documents.

When This Tool Won't Help Much

• PDFs with many high-res images — the images are the bulk of the file size, and this tool can't re-encode them.
• Already-optimized PDFs — exports from Adobe Acrobat or a modern browser often have compression already applied.
• Complex vector graphics — the paths are preserved without re-encoding.

Frequently Asked Questions

• Will compression change the quality? — For text-based PDFs, no. Text is vector data and remains crisp. For image-heavy PDFs, at High or Extreme levels, images may show subtle artifacts if they're re-encoded (though this tool's re-encoding is conservative).
• Can I undo compression? — No. The compression is applied to the file before download. Always keep a copy of the original.
• Are my files uploaded? — No. Everything happens in your browser. Your PDF never leaves your device.
• Is there a file size limit? — 100 MB for browser performance reasons. Very large PDFs may slow down the browser.
• Why didn't my PDF get smaller? — If the PDF was already compressed by the original tool, there's little room to improve. Try the Extreme level with all options enabled.

Related Tools

• PDF Merger — combine multiple PDFs into one.
• PDF Splitter — split a PDF into separate files.
• PDF to Word — extract text from a PDF into DOCX.
• Word to PDF — convert DOCX files to PDF.

Privacy Note

Everything runs in your browser using pdf-lib (a pure JavaScript PDF library). Your PDF never leaves your device, and the compressed file is generated entirely in memory until you download it.