No uploads.
No guesswork.
Just smaller.
Every other way to shrink a file asks you to hand it to a stranger's server, or to memorize a pile of Ghostscript flags. onadiet is neither: 100% local, it hits a target size (--to 5mb, not just "compress"), one tool for PDFs, images, and folders — with an honest measured before/after receipt held to a quality floor. Free and open-source, Apache-2.0.
npx onadiet report.pdf
--to 5mb
What makes onadiet different.
The alternatives are excellent at their one thing (we concede exactly where, below) — but no other tool does all of this at once, locally, with numbers it actually measured.
100% local, no upload
Nothing is uploaded — no account, no cloud, no network calls. Your file never leaves your machine, and the live demo's gauge proves every fetch/XHR stays at zero.
Hits a target size
Ask for a goal weight — --to 5mb — not just "compress". onadiet runs a size search to land under the limit while holding the quality floor, or refuses honestly instead of returning garbage.
One tool, every format
PDFs, images, SVGs, and whole folders — one command, one library. diet ./photos --to-total 25mb puts a directory under a budget with the structure preserved.
Honest measured receipt
Every saving is measured on the output and held to a perceptual floor (SSIM). It reports the real delta and the codec it chose — or keeps your original. A saving it didn't measure is a bug.
An embeddable engine
The same engine imports as @onadiet/core — embed it on a server hot path (~9× lower per-call latency with --fast), gate CI with diet check, or wrap it as an agent Skill.
Safe by default
Never overwrites your original, never writes a bigger file, writes atomically — and refuses to silently break a signed or form PDF rather than corrupt it.
onadiet vs. the usual suspects.
An honest matrix — where each tool wins is called out right after it. onadiet's column is highlighted; every ✓ here is something it actually ships today.
| Capability | onadietlocal CLI + library | TinyPNGweb / API | SquooshGoogle web app | ImageOptimMac app | GhostscriptCLI flags |
|---|---|---|---|---|---|
| Runs locally · nothing uploaded your file stays on your machine | ✓ | ✗ uploads to their servers | ✓ in-browser | ✓ | ✓ |
Hit a target file size
--to 5mb, not just "compress"
|
✓ size search | ✗ one-shot | ✗ manual sliders | ✗ | ✗ trial & error |
| PDFs + images + folders — one tool not five separate tools | ✓ | ~ images; PDF is a separate paid product | ~ one image at a time | ~ images only | ~ PDFs; images via flags |
| Honest measured receipt + quality floor real before/after, held to SSIM | ✓ | ✗ | ✗ | ✗ | ✗ |
| Safe by default never overwrite / never bigger; refuses signed PDFs | ✓ | ✗ | ✗ manual save | ✗ edits in place | ✗ you manage paths |
| Embeddable library · CI gate · scriptable import it, or fail a build on budget | ✓ | ~ paid API | ✗ | ✗ | ~ scriptable via flags |
| Free & open-source no paywall, inspectable | ✓ Apache-2.0 | ~ freemium / paid API | ✓ | ✓ | ✓ AGPL |
Where they shine — honestly. TinyPNG's PNG quantization and clean API are genuinely excellent. Squoosh is a lovely, free in-browser tool with superb manual codec controls. ImageOptim is a delightful drag-and-drop Mac GUI. And Ghostscript is battle-tested and immensely powerful. onadiet's angle is different: a target-size search, one tool across PDFs, images, and folders, honest measured receipts held to an SSIM floor, fully local, embeddable on a hot path, and safe by default.
Real files. Real savings. Every number measured on the output.
These are the same figures from the home page's benchmarks — proven against a genuinely public 9 MB SpaceX IPO-roadshow deck (60 pages, 224 images) in the golden-corpus test suite. Ask for a plan, or a target size — if it can't hit the target above the quality floor, it refuses honestly instead of returning garbage.
| Plan | Quality floor | 9.0 MB → | Reduction |
|---|---|---|---|
| cleanse | lossless | 9.0 MB | |
| lowcarb | SSIM 0.96 | 8.1 MB | |
| balanced | SSIM 0.90 | 4.8 MB | |
| keto | SSIM 0.80 | 3.7 MB | |
| crash | floorless | 3.3 MB |
Images too: a real photo (a NASA public-domain image, JPEG) → ~55% smaller at SSIM 0.94; a flat graphic (PNG) → 8 KB, ~99% smaller via an automatic switch to AVIF. Every figure is reproducible with pnpm run test:perf — no estimates.
Weigh in.
On npm now — early and 0.x, built and proven against real
files. Install it globally, or run it once with npx.
npm i -g onadiet
npx onadiet report.pdf
--to 5mb