How we test our tools
Last updated: 2026-10-03
Every size claim on this site comes from the same procedure: fixed test files, the production build, headless Chromium, and the real tool UI — not estimates. Full fixture definitions and the complete log live in docs/benchmark.md in our public repository.
Method
- Generate 8 fixtures (scanned document, photo-heavy, text-only, mixed, large 50 MB+, already-compressed, password-protected, corrupted).
- Drive the Compress PDF tool in Smart (default) mode end to end and record input bytes, output bytes, and wall time.
- Run input and output through the PDF-to-Text tool and compare extracted word counts to confirm text stayed selectable.
- Feed the password-protected and corrupted fixtures to confirm clear errors instead of hangs.
Results (measured 2026-10-03)
| File type | Original | Result | Saved | Time | Text selectable |
|---|---|---|---|---|---|
| Scanned document (5 full-page gray scans) | 13,946,069 B (13.3 MB) | 5,768,728 B (5.5 MB) | 58.6% | 1.5 s | yes |
| Photo-heavy (3 color photo pages) | 9,004,398 B (8.6 MB) | 1,999,451 B (1.9 MB) | 77.8% | 1.0 s | n/a (no text) |
| Text-only (5 text pages, no images) | 4,766 B | 4,766 B | 0% | 0.3 s | yes |
| Mixed (2 text + 2 image pages) | 2,141,397 B (2.0 MB) | 611,824 B (598 KB) | 71.4% | 0.3 s | yes |
| Large file (1 × 4200 px photo page, 50.5 MB) | 52,937,102 B (50.5 MB) | 1,763,887 B (1.7 MB) | 96.7% | 2.1 s | n/a (no text) |
| Already-compressed (tiny, efficient) | 1,606 B | 1,606 B | 0% | 0.3 s | n/a |
| Password-protected (RC4-encrypted) | — | — | — | — | clear error message, no hang |
| Corrupted (truncated at 55%) | — | — | — | — | clear error message, no hang |
What the numbers mean
- Image-heavy PDFs shrink a lot; text-only and already-optimal files do not shrink at all — the tool says so (under-5% notice) instead of pretending.
- Text extraction was word-identical before and after on every fixture containing text.
- The 50 MB file completed in about 2 seconds with sequential page processing; nothing hangs the tab.
Limitations
Processing runs on your device, so very large files depend on your browser memory (uploads cap at 150 MB). Password-protected PDFs must be unlocked by their owner first, and damaged files are rejected with an explanation. Results vary with file content — your mileage follows the same pattern as the table, not the exact percentages.
Try it yourself
- Compress PDF — Smart mode, target sizes, honest before/after numbers.
- Image Compressor — quality or exact-KB targets with previews.
- Image Resizer — exact pixels, aspect lock, batch + ZIP.
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