PDF Compressor
Compress a PDF with one-click presets (Smaller file, Balanced, Best quality) or manual quality/resolution control, with a live preview showing exactly what page 1 will look like — the real re-encoded output, not a simulation — before you compress anything. Effective for scanned or image-heavy documents; this flattens pages to images, so selectable text is lost afterward, not the right tool for a text-based PDF you need to keep searchable. Shows the exact before/after size and percentage reduction. Runs entirely client-side using pdf-lib and pdf.js — nothing is uploaded.
About this tool
This tool compresses a PDF by re-rendering every page as a JPEG at a quality and resolution you control, then rebuilding the PDF from those images — the same underlying approach as combining this site's PDF to Image and Image to PDF tools, but streamlined into one pass with compression-focused controls. Three presets (Smaller file, Balanced, Best quality) cover most cases with one click; an Advanced section exposes the raw quality and resolution sliders for fine control. A live preview re-renders page 1 at your actual current settings — the real re-encoded JPEG, not a simulation — so you can see the genuine quality tradeoff and an estimated total size before running the full compression. This is genuinely effective for scanned documents and image-heavy PDFs, where the original file size is already dominated by large or high-resolution images. It's the wrong tool for a mostly-text PDF you need to keep searchable, though: rasterizing converts every page into a flat image, so any selectable text is gone afterward, and a well-optimized text-based PDF may not shrink much (or could even grow) since text itself is already extremely compact compared to an image of that same text. It runs entirely client-side using pdf-lib and pdf.js — nothing you upload is ever sent anywhere.
What you can do
- Three one-click presets — Smaller file, Balanced, or Best quality — or fine-tune manually
- A live preview shows exactly what page 1 will look like at your current settings, before you compress anything
- See the exact before/after size and percentage reduction, visually
- Nothing is uploaded — compression happens entirely in your browser
How to use
Step 1
Upload a PDF
Its current size is shown immediately.
Step 2
Pick a preset and check the preview
The live preview updates instantly, so you see the real quality tradeoff before committing.
Step 3
Compress and download
See the exact size reduction, then get the compressed file.
Example
A 20-page scanned document at 15 MB:
Settings
Quality: 60% · Resolution: 1.5x
Result
15 MB → 3.2 MB (79% smaller)
a typical result for a scan-heavy PDF, where most of the size was already coming from oversized embedded images.
How your data is handled
This tool is labeled 🟢 Browser: your PDF is rendered, compressed, and rebuilt entirely in your browser using pdf-lib and pdf.js — nothing is uploaded to a server, and nothing about it is retained once you leave the page.
Frequently asked questions
Why did my file get bigger, not smaller?+
This can happen with an already text-efficient PDF — text itself is far more compact to store than an image of that same text, so converting a lean, mostly-text document into rasterized images at a high quality/resolution setting can genuinely increase file size. This tool works best on scanned or image-heavy PDFs.
Will the text still be selectable after compressing?+
No — every page becomes a flattened image, so there's no text layer left afterward, on any page, regardless of how much text it had. If you need to keep the document searchable, this isn't the right tool for it.
What's the difference between quality and resolution?+
Quality controls JPEG compression strength for each page's image — lower means smaller but more visible compression artifacts. Resolution controls how many pixels each page is rendered at — lower means a smaller, blurrier image. Both affect final file size; adjusting them together gets the best balance for a given document.
What settings should I start with?+
Balanced (60% quality, 1.5x resolution) is a reasonable starting point for most scanned documents — readable text, meaningfully smaller file. Use Smaller file for maximum compression, or Best quality if fine print needs to stay sharp. Check the live preview either way before committing.
Does the preview show the real result, or just an estimate?+
It's the genuine re-encoded JPEG for page 1 at your exact current settings — not a simulation — so what you see is what you'll get. The estimated total size just multiplies that page's size by the page count, since other pages may compress slightly differently.
Is my PDF uploaded anywhere?+
No — it's rendered, compressed, and rebuilt entirely in your browser. Nothing here ever leaves your device.