What Is ImageOptim?
ImageOptim is a free, open-source Mac desktop application that strips unnecessary metadata and applies lossless compression algorithms (pngcrush, optipng, advpng, mozjpeg, jpegoptim, Zopfli) to reduce PNG and JPG file sizes without any visual quality change. It's been trusted by Mac developers for over a decade.
Its strength is lossless compression — it makes files as small as possible without touching a single pixel. It's a drag-and-drop app: drop files or folders, it compresses them in place.
Platform: The Most Important Difference
ImageOptim is Mac only. There is no Windows version, no Linux version, and no official online version. If you're on Windows — which accounts for roughly 70% of desktop users — ImageOptim is simply not an option.
TinyPNG Now works on any device with a modern browser — Windows, Mac, Linux, iOS, Android, Chromebook. No download, no installation, no OS version requirements. Open the site and compress.
✅ Winner: TinyPNG Now — works on every platform, no installation needed.
HEIC and Modern Format Support
ImageOptim was designed around PNG and JPG. It has no support for HEIC (iPhone's default format), AVIF, or WebP input. If you shoot on an iPhone and want to optimize those photos, ImageOptim can't help directly.
TinyPNG Now handles HEIC natively. Upload iPhone photos and compress them as HEIC, or convert them to JPG or WebP in the same step.
✅ Winner: TinyPNG Now — full HEIC, WebP, and AVIF support.
Compression Quality: Lossless vs Lossy
ImageOptim is a lossless-first tool. It achieves typical reductions of 15–30% on PNG and JPG files with zero quality degradation. For design assets, UI elements, or screenshots where pixel-perfect quality is non-negotiable, lossless is the right choice.
TinyPNG Now offers both lossless and lossy compression. Lossy mode achieves reductions of 50–95% with imperceptible quality changes at the right settings — dramatically better for web performance. For product photos, blog images, and hero images where maximum file reduction matters more than perfect pixel preservation, TinyPNG Now's lossy compression wins on file size.
💡 The nuance: For a 4MB design PNG that needs pixel-perfect fidelity, ImageOptim's lossless 20% reduction is ideal. For a 3MB product photo going on your e-commerce site, TinyPNG Now's lossy 85% reduction (to ~450KB) is the right choice.
Online Access & Team Workflows
ImageOptim is a local desktop application. Non-Mac team members — Windows developers, Linux sysadmins, content managers on Windows laptops — cannot use it. Sharing files for optimization across a mixed-OS team requires workarounds.
TinyPNG Now is browser-based. Any team member on any OS can open it and compress files in seconds. No sharing of desktop apps, no OS compatibility issues.
✅ Winner: TinyPNG Now — works for every team member on any OS.
Privacy
Both tools are private. ImageOptim compresses files locally on your Mac — nothing leaves your machine. TinyPNG Now compresses files in your browser using WebAssembly — nothing leaves your device. For privacy-sensitive images, both are equally safe.
🤝 Tie — both are fully private, local processing tools.
Additional Tools
ImageOptim does one thing: compress PNG and JPG. That's it. No resize, no crop, no background removal, no format conversion, no watermark.
TinyPNG Now includes 25+ tools — resize, crop, rotate, background removal, EXIF remover, watermark, collage maker, color picker, QR generator, OCR, PDF conversion, and more. All free, all browser-based.
✅ Winner: TinyPNG Now — a complete image optimization suite, not just a compressor.
Head-to-Head Summary
| Feature | TinyPNG Now | ImageOptim |
|---|---|---|
| Platform | ✅ Any OS / browser WINNER | ❌ Mac only |
| Online / no install | ✅ Yes WINNER | ❌ Desktop install required |
| HEIC support | ✅ Yes WINNER | ❌ No |
| WebP / AVIF support | ✅ Yes WINNER | ❌ No |
| Max compression ratio | Up to 95% (lossy) WINNER | ~15–30% (lossless) |
| Lossless quality | Good | ✅ Excellent WINNER |
| Privacy | ✅ Browser-local | ✅ Mac-local |
| Extra tools | 25+ tools WINNER | Compress only |
| Price | ✅ Free | ✅ Free |
When to Use TinyPNG Now
- You're on Windows, Linux, mobile, or any non-Mac device
- You need to compress HEIC, WebP, or AVIF files
- You want maximum file size reduction for web performance (lossy compression)
- You need more than just compression — resize, crop, background removal, etc.
- You work in a mixed-OS team and need a tool everyone can use
When to Use ImageOptim
- You're on a Mac and need lossless compression with zero quality change
- You're compressing UI assets, icons, or screenshots where pixel-perfect quality is required
- You want to run lossless passes on files before or after other optimization tools
Frequently Asked Questions
Does ImageOptim work on Windows?
No. ImageOptim is Mac-only. TinyPNG Now works on any OS with a modern browser.
Is there an online version of ImageOptim?
No official online version exists. TinyPNG Now is a fully online, browser-based alternative that requires no upload to a server.
Does ImageOptim support HEIC?
No. TinyPNG Now supports HEIC natively.
Which gives better compression?
ImageOptim for lossless (preserves every pixel, ~15–30% reduction). TinyPNG Now for lossy (up to 95% reduction, imperceptible quality change for web use).