GhostScript's -dPDFSETTINGS flag maps to four internal configurations. /screen aggressively downsamples all colour images to 72 dpi — suitable only for on-screen viewing. /ebook uses 150 dpi, a good balance for tablet and desktop reading. /printer preserves 300 dpi for high-quality desktop or office printing. /prepress also uses 300 dpi but additionally preserves colour profiles (ICC), overprint settings, and halftone information required for commercial offset printing.
Free PDF Compressor — Online
Compress PDF Files — Powered by GhostScript
Reduce PDF file size for email, web, and archiving using GhostScript quality presets. Choose between Screen, eBook, Printer, and Prepress quality levels.
GhostScript quality presets
Up to 90% size reduction
Preserves text searchability
GhostScript Quality Presets — Estimated Size Reduction
| Preset | DPI | Est. Reduction | Best For |
|---|---|---|---|
| Screen | 72 | 60–90% | Email, web |
| eBook | 150 | 40–70% | Digital reading |
| Printer | 300 | 20–50% | Office printing |
| Prepress | 300 | 10–30% | Commercial print |
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Up to 100 MB free • Outputs: PDF
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Files deleted in 2h
Fast processing
No signup needed
Simple & Fast
How to Use PDF Compressor
Convert your files in three simple steps — no software, no signup.
01
Upload Your PDF
Drop your PDF file here. Multi-page PDFs and PDFs with embedded images are fully supported.
02
Choose Quality Preset
Select Screen (smallest), eBook (balanced), Printer (quality), or Prepress (professional) depending on your use case.
03
Download Compressed PDF
The compressed PDF downloads instantly. Text remains fully searchable and copyable.
Features
Why Use PDF Compressor?
GhostScript Engine
We use GhostScript's PDF distiller — the industry-standard engine used by professional print workflows for 30+ years.
Up to 90% Smaller
Scanned document PDFs with embedded high-res images can be reduced by 70–90% at Screen quality with minimal visual loss.
Text Always Searchable
Unlike image-based compression, GhostScript preserves vector text so PDFs remain fully searchable and copyable.
Smart Image Downsampling
Embedded images are intelligently downsampled to match the chosen DPI preset — not blindly flattened.
Secure & Private
Documents are processed in isolated containers and deleted within 2 hours. No content scanning or indexing.
Fast Bulk Processing
A 100-page PDF with embedded images typically compresses in under 10 seconds using our server-side GhostScript pipeline.
Compatibility
Supported Formats
All the formats you need, all in one place.
| Format | Description | Extension | Best Used For |
|---|---|---|---|
| SCREEN (72 DPI) | /screen — Lowest quality, smallest file. Images downsampled to 72 dpi. | .pdf |
Email attachments, web download links |
| EBOOK (150 DPI) | /ebook — Good quality for on-screen reading. 150 dpi images. | .pdf |
Digital distribution, tablets, e-readers |
| PRINTER (300 DPI) | /printer — High quality suitable for desktop printing. 300 dpi images. | .pdf |
Office printing, reports, presentations |
| PREPRESS (300 DPI) | /prepress — Professional print quality with colour profiles preserved. | .pdf |
Commercial printing, design files |
| DEFAULT | /default — GhostScript default, similar to Printer quality. | .pdf |
General purpose compression |
FAQ
Frequently Asked Questions
Screen for email (smallest, web view only). eBook for digital documents on tablets. Printer for documents you will print at home or office. Prepress only for commercial print production.
No. Vector text (typed text) is preserved perfectly at all quality levels. Only embedded raster images are downsampled based on the selected DPI preset.
PDFs already containing only vector text and minimal images may only shrink 10–20%. PDFs from scanned documents or with many high-res photos can reduce 70–90% at Screen quality.
No — existing PDF passwords and permissions are preserved. If you want to remove a password as part of compression, enter the password in the options field.
Yes. GhostScript re-distils the PDF but preserves all text layers. Scanned PDFs without OCR are image-only regardless — use the OCR Tool to add a text layer first.
Both use 300 dpi images but Prepress also preserves colour profiles (ICC), overprint settings, and transfer functions required for professional offset printing. For office use, Printer is identical.
Real-World Uses
Who Uses PDF Compressor?
From everyday users to professionals — see how people rely on this tool every day.
Office Worker
Shrink PDF for Email
Many email systems cap attachments at 10–25 MB. Use Screen preset to reduce a scanned report from 40 MB to under 5 MB.
Web Developer
Optimise for Web Download
Reduce PDF brochure or catalogue file size so visitors download it quickly on mobile connections.
Publisher
Digital Distribution of eBooks
Use eBook preset (150 dpi) to balance reading quality and download speed for PDF books distributed online.
Print Designer
Prepare Print-Ready Files
Apply Printer preset to ensure 300 dpi image resolution that meets desktop and professional print requirements.
Records Manager
Long-Term Archive at Smaller Size
Compress bulk scan archives with eBook or Printer quality to halve storage costs without losing document legibility.
Remote Worker
Share via Mobile Hotspot
Compress large PDFs before sending through file-sharing apps to save mobile data and speed up uploads.
Why HarmonyPal?
HarmonyPal vs. Alternatives
See how we compare to desktop software and other online converters.
| Feature |
Our Tool HarmonyPal |
Adobe Acrobat | Other Online |
|---|---|---|---|
| GhostScript quality presets | Limited | ||
| Text remains searchable after compression | |||
| Adjustable image DPI | |||
| Preserves PDF passwords/permissions | Varies | ||
| No watermark on output | |||
| Free to use | |||
| No software installation | |||
| Batch processing |
Under the Hood
Technical Specifications
Built on industry-standard open-source tools for maximum quality and reliability.
Limits & Restrictions
- Max file size: 100 MB (free)
- Output format: PDF only
- No hard page count limit
GhostScript
PDF
Compression
dpi
Optimise
Conversion Engine
GhostScript 10.x PDF distiller (industry standard since 1988)
Output Quality
Screen 72 dpi / eBook 150 dpi / Printer 300 dpi / Prepress 300 dpi + ICC profiles
Average Speed
Typical: 5–15 s for a 10 MB scanned PDF; large files scale linearly
Data Security
HTTPS transfer · isolated temp dir · auto-purged in 2 h
Max reduction
Up to 90% (Screen preset, image-heavy PDF)
Text handling
Vector text fully preserved at all presets
Max file size
100 MB
Complete Guide
How PDF Compression Works: GhostScript Presets and Image Downsampling Explained
PDF compression is not a single operation — it is a combination of image downsampling, font subsetting, object stream compression, and metadata trimming. GhostScript orchestrates all of these under its quality preset flags.
The Four GhostScript Quality Presets
Why Text PDFs Compress Less
A PDF composed entirely of vector text (like one exported from Word or InDesign) already stores text as compact mathematical descriptions — not as pixels. GhostScript can still apply Flate compression to object streams, but the gains are modest (10–25%). The dramatic 60–90% reductions happen only when the PDF contains many high-resolution embedded raster images, which are downsampled to the preset DPI.
Font Subsetting During Compression
During re-distillation GhostScript also subsets embedded fonts — stripping out the glyph data for characters not used in the document. A font that originally contained 1,200 glyphs may only need 80 for a particular document. Font subsetting alone can save several hundred kilobytes in font-heavy documents.
Scanned PDF vs Digital PDF
Scanned PDFs consist of full-page raster images at 300–600 dpi per page. A 50-page scan at 300 dpi can easily exceed 30 MB. Compressing with Screen preset reduces each page image to 72 dpi — often achieving 80%+ reduction with minimal impact on legibility for text documents. For archival use, eBook (150 dpi) is a safer choice that retains clear text at a significantly smaller size.
When Compression Will Not Help
If your PDF was already compressed with GhostScript at the same or higher quality setting, re-running compression will not make it significantly smaller and may slightly inflate the file due to overhead in the new cross-reference table. PDFs that are already below 1 MB rarely benefit from further compression.