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A comprehensive breakdown of features, formats, and workflows to help you choose the right image optimizer for your team.
FastCompressor wins for: cross-platform teams, TIFF, video, modern formats (AVIF, WebP), folder automation, Windows and Linux users.
ImageOptim wins for: free-forever Mac-only use, lossless JPEG/PNG optimization, developer CLI pipelines, teams that already know and trust it.
Get unlimited batch compression, folder watch automation, and support for modern formats like WebP, AVIF, and TIFF. All for a one-time payment.
| Feature | ImageOptim (Desktop) | FastCompressor (Free) | FastCompressor Pro |
|---|---|---|---|
| Price | Free (donationware) | Free | $19 once — no renewal |
| Platform | macOS only | macOS, Windows, Linux | macOS, Windows, Linux |
| Formats supported | JPEG, PNG, GIF, SVG | JPG, PNG, WebP, TIFF, AVIF, GIF, video | JPG, PNG, WebP, TIFF, AVIF, GIF, video |
| TIFF support | No | Yes | Yes |
| WebP support | No | Yes | Yes |
| AVIF support | No | Yes | Yes |
| Video compression | No | Yes | Yes |
| Format conversion | No (optimize only) | Yes (e.g. JPG → WebP) | Yes |
| Files uploaded to server | Never | Never | Never |
| Works offline | Always | Always | Always |
| Batch processing | Unlimited (drag folder) | Up to 20 per session | Unlimited |
| EXIF/metadata removal | Auto (on by default) | Manual | Batch removal |
| Folder watch / auto-compress | CLI only | No | Yes (Pro) |
| Windows support | No | Yes | Yes |
| Linux support | No | Yes | Yes |
| Actively maintained | ! Limited (last major update 2021) | Active | Active |
ImageOptim is a Mac-only utility that compresses JPEG, PNG, GIF, and SVG files. It operates by passing files through various open-source compression engines (such as MozJPEG and pngquant) and saving the smallest output. It focuses primarily on lossless compression.
By default, ImageOptim strips EXIF metadata (like GPS and timestamps), which can help reduce file sizes.
While ImageOptim is a free and straightforward option for users needing basic JPEG and PNG compression on macOS, it lacks support for modern formats like WebP or AVIF.
Windows and Linux are not supported. ImageOptim is macOS only. In 2016, a GitHub issue requested Windows support. In 2021, the ImageOptim maintainer publicly explained why it can't be built: the codebase is written in Objective-C and AppKit, tightly coupled to macOS frameworks that don't translate to other platforms. As of June 2026, Windows support has still never been delivered. If your team includes Windows or Linux users, they cannot use ImageOptim at all.
TIFF is not supported. ImageOptim silently rejects TIFF files. Photographers and print designers who work with Lightroom TIFF exports or archival scans have no option within ImageOptim. FastCompressor compresses TIFF losslessly using LZW or Deflate, automatically selecting the better algorithm based on the file's bit depth.
WebP and AVIF are not supported. ImageOptim supports four formats: JPEG, PNG, GIF, and SVG. A 2019 GitHub issue requesting WebP support was closed without the feature being added. In 2026, WebP has 97% browser support and AVIF is increasingly standard. ImageOptim cannot output either format.
No format conversion. ImageOptim can optimise a PNG but cannot convert it to WebP. FastCompressor converts between formats in the same compression operation — compress a folder of JPGs to WebP in one step.
No active development. The maintainer noted in a 2021 GitHub post that the codebase has become difficult to extend. The last significant update was in 2021. FastCompressor is actively maintained with regular updates.
Both tools process locally with no upload. We tested both tools with a batch of 4 high-resolution JPG files (Original total size: ~18.4 MB).
You're a solo Mac developer who only needs JPEG and PNG for web use — ImageOptim for the free lossless pass, FastCompressor for TIFF or video work when those come up.
Photography studio (rejected ImageOptim):
A wedding photographer delivering 500 edited TIFFs to a client tried ImageOptim. It rejected every file silently — TIFF is not supported. They switched to FastCompressor, which compressed the full 500-file TIFF delivery in under 3 minutes with lossless LZW compression.
FastCompressor supports TIFF, AVIF, WebP, and Video out of the box.
Design agency on Mac and Windows:
The Mac designers used ImageOptim. The Windows team had no equivalent tool. Switching to FastCompressor standardised the compression workflow across all platforms — same app, same quality settings, same output on every machine.
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