Compress PDF Online Free

PDF compression reduces file size by optimizing the document's internal structure — downsampling high-resolution images, removing duplicate resources, compressing content streams, and stripping unnecessary metadata. AuraPDF uses Ghostscript, the industry-standard open-source PDF processing engine trusted by enterprises and government agencies worldwide, to deliver compression ratios of up to 90% while maintaining visual fidelity.

Three compression presets give you precise control: Low compression (300 DPI — maximum quality, ideal for print), Medium compression (150 DPI — balanced, perfect for screen viewing and sharing), and High compression (72 DPI — smallest file size, ideal for email attachments and web uploads). The engine applies intelligent optimization — lossy compression for embedded images where quality reduction is least noticeable, and lossless compression for text, fonts, and vector graphics where quality must be preserved.

PDF compression solves critical real-world problems. Gmail enforces a 25 MB attachment limit. Outlook limits attachments to 20 MB. Many web upload portals cap file sizes between 5–10 MB. Government submission portals, insurance claim systems, and university assignment portals often restrict uploads to 10–25 MB. Uncompressed PDFs containing scanned pages or high-resolution images easily exceed these limits — AuraPDF's engine can reduce a 50 MB scan-heavy PDF to under 5 MB instantly.

The compression engine handles every PDF content type. Image-heavy documents (scanned contracts, photo portfolios, brochures) benefit most — downsampling 600 DPI scans to 150 DPI can reduce file size by 70-90% with negligible visible difference on screen. Text-heavy documents (reports, briefs, manuals) are optimized through stream compression and resource deduplication. Font subsetting removes unused glyphs. Metadata stripping removes editing history, application info, and timestamps that add unnecessary bytes.

After compressing, optimize further with Merge PDF to combine compressed files, Add Page Numbers for professional pagination, Add Watermark for branding, or Protect PDF for password security.

All uploads encrypted with TLS 1.3. Files processed in isolated environments and auto-deleted within 30 minutes.

For users with specific file size targets, AuraPDF’s compression engine can reduce PDFs to precise size ranges. To compress PDF to 100KB — select High compression; most text-only or image-light PDFs will compress below 100KB. To compress PDF to 200KB or compress PDF to 500KB — use Medium compression for an optimal balance between quality and file size reduction. To compress PDF to 1MB — even Low compression on multi-page image-heavy PDFs typically achieves results under 1MB. The actual output size depends on content type: scanned PDFs with images compress 70–90%, text-only PDFs compress 20–40%, and mixed-content documents fall in between. For email-specific optimization, use High compression to ensure your PDF stays well under Gmail’s 25MB limit, Outlook’s 20MB limit, and corporate Exchange limits of 10–15MB.