Starlight Tools

Compress PDF Online Free

Reduce PDF file size for email, uploads, 10 MB, 5 MB, 2 MB, or custom limits without uploading the file. Compression runs in your browser so private documents stay on your device.

  • No upload
  • Runs in your browser
  • No watermark
  • No sign-up
  • Files stay on your device

Compress PDF

Drag PDFs here or click to choose files
Single PDF or batch compression, all processed locally.
Selected file: None
Original size: N/A
Page count: N/A

Waiting to start.

Compression Settings

Advanced options
144 DPI
Used in scanned PDF mode.
72%
Used when pages are rasterized to JPEG.

Browser PDF libraries support cleanup and full-page raster compression. Some deep object optimizations depend on the PDF structure and may save little space.

Preview

Page 1 of 1

No PDF selected. The canvas preview will show the first selected PDF.

Use Previous and Next, or the left and right arrow keys while the preview controls are focused.

Compression result

Original sizeN/A
New sizeN/A
SavedN/A
TargetN/A
PagesN/A
PresetN/A

  • No upload
  • No watermark
  • Files stayed on your device

How to compress a PDF

  1. Choose one or more PDFs or drag them into the upload area.
  2. Pick a compression preset, mode, or target size such as under 10 MB or 5 MB.
  3. Click Compress PDF and keep the tab open while the browser processes each page.
  4. Review the original size, new size, saved percentage, page count, preset, and target-size result.
  5. Download the compressed PDF, individual batch files, or a ZIP.

Use scanned PDF mode when pages are mostly images. Use preserve text and links when selectable text, links, forms, signatures, or annotations matter more than maximum shrinkage.

Practical PDF compression examples

Reduction percent = (original size - compressed size) / original size x 100.

PDF typeRecommended settingLikely result
Scanned 20 MB PDFScanned mode, Recommended or Smallest fileOften shrinks well because page images can be downscaled and re-encoded.
Image-heavy reportScanned mode, Recommended, target under 10 MBGood savings, but photos may look softer at aggressive targets.
Text-only contractPreserve text and links or Lossless cleanupSmaller savings, but selectable text and links are more likely to remain intact.
ResumeBest quality or Preserve text and linksUsually keeps crisp reading quality while trimming metadata and structure.
School formPreserve text and links unless it is a scanUse scanned mode only if upload limits matter more than interactive fields.
Print-ready brochureBest quality or custom high DPICompression may be limited because print images need detail.

PDF compressor FAQ

Is it safe? Does the file upload?

Yes. The compressor runs in your browser. Your PDFs are not uploaded to Starlight Tools, and the page does not add watermarks or require an account.

Why did my PDF not get smaller?

Some PDFs are already optimized, mostly text, encrypted, or built from images that are already heavily compressed. Preserve and lossless modes may also save less because they avoid rasterizing pages.

Does compression reduce quality?

Scanned PDF mode can reduce visual quality because it renders pages as JPEG images. Best quality, preserve text, and lossless cleanup are better when appearance and selectable text matter.

Can I compress to 1 MB or 5 MB?

You can choose under 5 MB, under 2 MB, or a custom 1 MB target. The tool tries progressively smaller raster settings and reports clearly if the target is not realistically reachable.

Are links, forms, signatures, and annotations preserved?

Use Preserve text and links or Lossless cleanup for those files. Scanned PDF mode rasterizes each page, so interactive PDF features and accessibility tags may not survive.

Can I compress password-protected PDFs?

Most protected PDFs need to be unlocked first. Browser libraries generally cannot rewrite encrypted files without the correct permissions.

What is best for scanned PDFs?

Choose Best for scanned PDFs with Recommended for normal use or Smallest file for strict upload limits. Scans usually shrink most because the visible page is one or more images.

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