Melt guide

ImageOptim vs Melt on Mac — which should you use?

Both are drag-and-drop image compressors for Mac. Here's the actual difference and which makes sense for which job.

4 min read

You’ve heard of ImageOptim. You’ve heard of Melt. They both do drag-and-drop image compression on Mac. So which one? The honest answer depends on what you’re optimising and how much control you want.

What ImageOptim is

ImageOptim is a free, open-source Mac app maintained for years by Kornel Lesinski. It bundles a bunch of compression tools (pngquant, MozJPEG, Zopfli, OptiPNG, JpegOptim, gifsicle, SVGO) and runs them in series. Defaults are aggressive but reasonable. It overwrites the original file in place.

The killer feature: it’s free.

The catch: the interface is one window with a queue. Quality settings live in Preferences and apply globally. You don’t see per-file decisions, you can’t resize, and you can’t convert between formats. It compresses, that’s it.

What Melt is

Melt is a paid ($9.99 one-time) Mac app that does:

It outputs new files instead of overwriting originals, has per-batch settings, and shows a progress bar with per-file size deltas.

Which one when

Use ImageOptim if: you want pure compression, you don’t need format conversion or resize, you’re comfortable with in-place overwriting, and free is the deciding factor. It’s a perfectly good tool — it’s been the default recommendation in Mac dev circles for over a decade.

Use Melt if: you also need to resize, convert HEIC to JPEG, want non-destructive output, batch a lot of mixed-format folders, or care about the EXIF strip happening automatically. The $9.99 is one-time, no subscription.

Compression quality

Honestly, this is a wash. Both wrap pngquant for PNG, both use MozJPEG-grade encoding for JPEG. A PNG compressed in ImageOptim and the same PNG compressed in Melt at equivalent quality settings land within a few percent of each other. The compression itself isn’t the differentiator.

What about the Terminal?

If you’re comfortable with pngquant, jpegoptim, and mogrify, you don’t technically need either app:

brew install pngquant jpegoptim && pngquant —quality=70-90 *.png

The apps exist because remembering flags for five different binaries gets old.

The pitch for trying Melt

Download Melt for $9.99 if you regularly do mixed jobs — “compress this folder, convert the HEICs, resize everything to 2000px, strip EXIF.” That’s where the GUI starts paying for itself. For pure single-format compression of a folder of PNGs, ImageOptim is genuinely fine.

  1. Download Melt if you want to try it.
  2. Drag a folder in.
  3. Pick output format, quality, and optional resize.
  4. Click Compress. Outputs save next to originals.

There’s no wrong answer here. Both shrink images. The right tool is the one that matches your workflow.

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