Drop a PDF into the upload box on the left. You'll see the compression result here after processing.
A PDF can get big for two very different reasons. The first is internal bloat — unused objects, duplicate fonts, verbose metadata, and inefficient cross-reference tables. The second is heavy content — high-resolution images, scans, or hundreds of embedded photos.
Most online PDF compressors only address one of these. This tool handles both, and lets you choose which approach fits your file.
| Approach | What it does | Typical savings | Trade-off |
|---|---|---|---|
| Lossless optimization | Rebuilds the PDF's internal structure, removes duplicate objects, strips metadata, and compresses object streams. | 10–30% | None. Text stays selectable, images stay original. |
| Lossy recompression | Re-renders every page as a JPEG image at a lower quality setting, then rebuilds the PDF from those images. | 60–90% | Text becomes part of the image — no longer selectable or searchable. |
Traditional compressors use a fixed setting — "Low," "Medium," or "High" — and you just hope it lands under your limit. If it doesn't, you try again. This wastes your time.
Target-size mode works differently. You enter a limit (say, "2 MB"), and the tool uses binary search over JPEG quality:
The result: you get the highest possible quality that fits your limit, without guessing. Binary search typically finds a good answer in 4–6 passes.
What changes internally: metadata (title, author, keywords) may be stripped, unused objects removed, and object streams compressed into a more efficient layout.
The visual appearance is preserved — the PDF looks like the original when viewed or printed. But the structure underneath is now a sequence of images.
Most free PDF compressors upload your file to their servers. You wait while a machine you can't see processes your document. For a public brochure, that's fine. For a signed contract, a medical record, or a bank statement, it's a real risk.
This tool works differently. Everything runs inside your browser. The PDF is opened directly from your device's storage, compressed in memory, and written back out. No upload, no server, nothing to leak.
Your PDF was already well-optimized. Text-only PDFs made by modern tools are already tightly packed — lossless compression has nothing to remove. Try lossy mode instead, or accept that a 200 KB text PDF doesn't need shrinking.
This can happen in lossless mode if the original was saved with an older, more compact encoding. If the compressed file is larger than the original, keep the original — there's no benefit to a bigger file.
That's lossy mode doing its job. The quality slider controls how much blur is acceptable. Slide it toward "High" (0.8) for sharper output at the cost of a larger file. For text you need to read closely, use lossless instead.
Lossy mode converts pages to images, so text becomes pixels. If you need selectable text, switch to lossless mode. Unfortunately you can't have both maximum compression and selectable text.
Lossy compression re-renders every page, so a 100-page PDF takes longer than a 10-page one. Target-size mode is even slower because it re-renders the whole document up to 6 times. The progress bar shows exactly what's happening.
| Task | Tool | What it does |
|---|---|---|
| Make one PDF smaller | Compress PDF | Reduces the file size of a single PDF |
| Combine 5 PDFs into 1 | Merge PDF | Joins multiple PDFs into one larger file |
| Split one PDF into 10 | Split PDF | Divides one PDF into smaller PDFs |
| Remove sensitive text | Redact PDF | Blackout content permanently before sharing |
| Photos → one PDF | Image to PDF | Combine JPG/PNG/WebP photos into a PDF |
Yes. Here's exactly what happens when you use this tool:
At no point does the file leave your device. No data is sent to SkillsInsider's servers. No tracking cookies watch your compression. You can prove it yourself: turn off your Wi-Fi after the page loads, then compress a PDF. It still works perfectly.
Yes — completely free. No sign-up, no watermark, no page or file-size limit beyond your browser's memory. Use it as often as you need.
No. Everything runs locally in your browser using pdf-lib and PDF.js. Your file never leaves your device.
It depends on the file. Text-heavy PDFs typically shrink 10–30% in lossless mode. Image-heavy or scanned PDFs can shrink 60–90% in lossy mode. Already-optimized PDFs may not shrink at all.
Lossless mode does not affect quality at all — it only restructures internal data. Lossy mode re-renders pages as JPEG images, so text becomes part of the image and is no longer selectable. For scanned documents this is fine; for text-heavy PDFs, use lossless.
Yes. Enter a target size like 2 MB and the tool uses binary search to find the best JPEG quality that fits. It tries up to 6 quality levels automatically.
In lossless mode, yes — text is preserved. In lossy mode, no — text becomes part of the image and cannot be selected or searched.
Once the page has fully loaded, yes. Turn off Wi-Fi and it still compresses — all processing happens locally on your device.
Compress reduces the size of one PDF. Merge combines many PDFs into one. They solve different problems and are often used together — merge first, then compress the result.
