Compress PDF

Why Compress PDF Files?

Large PDF files are one of the most common digital frustrations. Email attachment limits (typically 25 MB for Gmail, Outlook, and Yahoo) block oversized PDFs. Upload portals for job applications, government forms, and university submissions enforce strict file size limits. Sharing large PDFs over messaging apps is slow and wastes mobile data.

According to Google (2024), 53% of mobile users abandon sites that take longer than 3 seconds to load — oversized PDFs embedded on web pages are a major culprit. The HTTP Archive reports that images and documents account for nearly a third of a typical web page's total weight.

PDFJolt's PDF compressor solves this instantly — directly in your browser, with zero file uploads to external servers.

How PDFJolt Compression Works

PDFJolt processes your PDF entirely client-side using WebAssembly. Your file never leaves your device — it's rendered page by page at a target resolution, then reassembled into a smaller PDF. This approach reliably compresses any PDF content: scanned documents, photos, vector graphics, and mixed layouts.

Choose from three compression levels depending on your needs:

• Light (30-50% smaller) — Renders at 150 DPI with high JPEG quality. Ideal when you need the document to look nearly identical to the original. Perfect for professional reports and presentations.
• Medium (50-70% smaller) — Renders at 120 DPI with balanced JPEG quality. The best default choice for most use cases: emailing documents, uploading to portals, and general sharing.
• Aggressive (70-90% smaller) — Renders at 72 DPI with lower JPEG quality. Best for documents where readability matters more than image sharpness — forms, text-heavy reports, and archival copies.

Common Use Cases

Email Attachments

Most email providers cap attachments at 25 MB. A scanned multi-page document can easily exceed this. PDFJolt's Medium preset typically brings a 30 MB scan down to under 10 MB while remaining perfectly readable.

Job Applications & Government Portals

Many application portals require PDFs under 2-5 MB. Use the Aggressive preset to meet strict limits without losing text readability.

Website & Cloud Storage

Compressed PDFs load faster on websites, save cloud storage space, and reduce bandwidth costs. Organizations processing thousands of documents per month can save significant storage costs.

PDFJolt vs Other PDF Compressors

Feature	PDFJolt	Adobe Acrobat	iLovePDF	Smallpdf
Price	Free	$19.99/mo	Free (limited)	$12/mo
Privacy	Files never uploaded	Cloud processing	Server upload	Server upload
Compression Levels	3 presets	4 presets	2 presets	1 preset
File Size Limit	50 MB (free)	Unlimited (paid)	25 MB (free)	5 MB (free)
Works Offline	Yes	Desktop only	No	No
Account Required	No	Yes	No (limited)	No (limited)
Batch Processing	Coming soon	Yes	Yes (paid)	Yes (paid)

Technical Details

PDFJolt's compression engine uses two proven open-source libraries:

• pdf.js (by Mozilla) — Renders each PDF page to an HTML5 canvas at the target DPI resolution. This is the same engine that powers Firefox's built-in PDF viewer.
• pdf-lib — Assembles the rendered page images into a new, optimized PDF with object streams for minimal overhead.

The combination of resolution downscaling and JPEG compression produces reliable, predictable file size reductions across all types of PDF content.

Privacy & Security

Unlike every major competitor, PDFJolt never uploads your files to a server. Your PDF is processed entirely in your browser using WebAssembly technology. No data leaves your device, no files are stored on any server, and no account is required. This makes PDFJolt the safest choice for compressing confidential documents — legal contracts, medical records, financial statements, and personal identification.

Need Help With a Specific Problem?

• Is your PDF too large to email or upload? See our guide with specific size limits for common portals.
• Getting a PDF upload error on a website? We'll help you diagnose and fix it.

Tips for Best Results

• Start with Medium compression — it works well for 90% of use cases.
• Use Light if the PDF contains detailed charts, diagrams, or photographs that need to remain crisp.
• Use Aggressive when you need to meet a strict file size limit and the document is primarily text.
• For scanned documents that are already image-based, all three presets will produce significant reductions.
• If the compressed file is still too large, try a higher compression level.