压缩 PDF
无明显质量损失地压缩PDF文件。免费、快速、安全。
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仅限PDF — 最大 50 MB
压缩级别
Publicité
实际效果
典型文件的实际压缩示例
前 / 后
之前
之后
60%
平均压缩率
8s
平均时间
按模式压缩比
"几秒内将PDF从4MB压缩到1.2MB，非常适合发送邮件！"
How to compress a PDF online for free?
Compressing a PDF reduces file size by up to 70% with no visible quality loss. FileSwiftly uses Ghostscript, a professional PDF processing engine, to handle your files directly in the browser — no installation or account required.
Three PDF compression levels explained
Maximum mode shrinks the PDF to the smallest possible size by downscaling embedded images to 72 dpi — perfect for email attachments (10–25 MB limits) and instant messaging. Recommended mode targets 150 dpi, giving the best balance between file size and visual quality — ideal for web publishing, digital presentations, and archiving. Quality mode applies light compression at 300 dpi, preserving full fidelity for professional printing, legal documents, and high-resolution screen review.
Which PDF types can be compressed?
Our online PDF compressor supports all standard PDF files: business reports, PowerPoint or Keynote-exported presentations, administrative forms, marketing brochures, eBooks, and invoices. PDFs containing high-resolution photos, diagrams, or screenshots benefit the most — typically 60–80% reduction. Text-only PDFs see moderate reduction of 10–30% since text is already efficiently encoded in the PDF format.
PDF compression vs. image conversion
Unlike tools that convert your PDF to images and reconstruct it — permanently degrading text clarity and vector graphics — FileSwiftly uses Ghostscript to recompress the native PDF stream. Text remains selectable and copyable, hyperlinks stay functional, and vector fonts keep their crispness at any zoom level. This is the method used by professional printers and DTP specialists worldwide.
Security and privacy
Your files are transferred over TLS 1.3 HTTPS, processed in complete isolation on secure servers (no human access to content), then automatically deleted after 1 hour. No data is retained, indexed, or shared with third parties. FileSwiftly is GDPR-compliant and requires no account — privacy is protected by design.
FAQ
Why compress a PDF?
A compressed PDF downloads faster, fits within email attachment limits (typically 10–25 MB), uses less storage space, and renders faster in browsers and PDF viewers — essential for documents shared online, client portals, and digital archives.
Does compression affect text quality?
No. Text, vector fonts, and vector graphics are not affected — only embedded bitmap images have their resolution adjusted. In Recommended mode the difference is imperceptible even on Retina displays.
Can I compress a password-protected PDF?
No, a locked PDF cannot be compressed directly. First unlock it using our Unlock PDF tool, then compress the unlocked file.
What is the maximum file size?
The free tool accepts PDFs up to 50 MB. FileSwiftly Pro supports files up to 500 MB with batch compression of up to 50 files simultaneously.
需要更多？
Pro版支持一次压缩12个PDF
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