# Compress PDF Files

> Most PDF compressors upload your file. This one doesn't. Pick a quality preset (low / medium / high), watch the live size estimate update against the original, and save the smaller file when it looks right. Compression runs in the browser via pdf-lib, so an 80 MB tax return or a draft contract never lands on someone else's server. The math is the same as Smallpdf or iLovePDF; the upload round-trip isn't there.


Live tool: https://lofttools.com/tools/pdf-tools/compress-pdf

Category: PDF & Documents


## What it does

- Three quality presets — low, medium, high
- Live size estimate updates against the original before download
- Image stream re-encoding (JPEG quality + downsampling tuned per preset)
- Font subset re-encoding to drop unused glyphs
- Bookmarks, hyperlinks, form fields, and annotations preserved through compression
- PDF/A flag preserved when input is PDF/A
- pdf-lib backed, runs in the browser tab
- No file size limit beyond what the browser can hold in memory
- Multi-page PDFs supported in a single pass

## How it works

1. **Select PDF** — Drop the PDF you want to shrink, or click to browse
2. **Choose quality** — Select compression level — high, medium, or low
3. **Download** — Get your compressed PDF instantly

## FAQ

### What is the maximum file size?

Up to 100MB per file. Premium users can process larger files.

### Does this preserve bookmarks and form fields?

Yes. Compression rewrites image streams and re-encodes fonts, but bookmarks, hyperlinks, form fields, and annotations carry over to the smaller file.

### What PDF versions are supported?

PDF 1.0 through 2.0. The output PDF version follows the input; downgrades are not performed.

## Privacy — what we do not do

This tool runs entirely in the browser via WebAssembly. Your file never reaches a Loft Tools server. Specifically:

- **No upload.** The file bytes load into the browser tab's memory and process on your own CPU. Open DevTools → Network and observe zero outbound requests carrying file data while Compress PDF Files runs.
- **No AI training on your file.** Loft does not train models. We could not train on a file we cannot see.
- **No content scanning.** No virus, copyright, or content-moderation pass against your file. The bytes are not accessible to us.
- **No server-side log of file contents, filenames, or EXIF metadata.** Cloudflare edge captures URL and truncated IP for abuse defense (standard CDN behaviour). Cloudflare Web Analytics records anonymous page hits, no cookies, no PII. Nothing about your file content reaches any log.
- **No retention.** Close the tab and the file leaves browser memory. No backups exist on our side because no copy ever existed on our side.
- **No account.** No email, no signup, no auth, no telemetry tied to you.
- **Offline-capable after first visit** (PWA). Once you've loaded a tool, it caches; later sessions work without internet. For high-sensitivity files, run the tool once online to warm the cache, then disconnect before processing.

Compare with upload-based services: each transmits your file to a processing server. Even over HTTPS, each has logs, retention windows, and subpoena exposure. Loft has none of these because the server architecture does not include your file.

## More

- All tools: https://lofttools.com/tools
- Category: https://lofttools.com/tools/pdf-tools
- LLM index: https://lofttools.com/llms.txt