Compress
Each image stays in its original format — a JPEG stays a JPEG, a PNG stays a PNG. Melt re-encodes it tighter, strips metadata, and only keeps the result if it's actually smaller. Good for cleaning up a folder of photos before sharing.
Melt is a focused little Mac app for shrinking, converting, and resizing images — one at a time or by the folder. This guide walks through everything Melt does, why every option is there, and how to get the smallest possible file without giving up the quality you care about.
When Melt opens, the whole window is one big drop target. There are three ways to add images, all completely equivalent — use whichever fits the moment:
Drop a single image, a Finder selection, or a whole folder anywhere onto the window. Subdirectories aren't traversed — pick the leaves you want, and Melt picks up every image format macOS knows how to read.
The Choose Images… button in the centre of the drop
zone opens the standard macOS picker. Same on the File menu
(⌘O). Multi-select with ⌘ or ⇧
to add a batch in one go.
Copied an image somewhere — a screenshot, an image from a browser, a
file selection in Finder? Hit ⌘⇧V and Melt picks it up.
Raw pixel data (PNG / TIFF) is written to a temp file first so Melt
can treat it like any other source.
Once images are in the queue you can drag more in at any time — the queue keeps growing until you Compress or Clear it.
Once images are in the queue, an options panel slides in on the right. The first decision is the mode at the top: do you want Melt to shrink each image in its current format, or convert everything to a new one?
Each image stays in its original format — a JPEG stays a JPEG, a PNG stays a PNG. Melt re-encodes it tighter, strips metadata, and only keeps the result if it's actually smaller. Good for cleaning up a folder of photos before sharing.
Every image is re-saved in one chosen format: JPEG, PNG, or HEIC. Useful when you want a consistent set — e.g. a wedding folder all as JPEG, or a screenshot archive all as HEIC for storage savings.
Only one mode applies per run. If you need both — convert and compress, say — run the batch twice: convert first, then compress the results.
Compression in Melt is a single decision — four named levels that map to a JPEG quality factor under the hood. Each one strikes a different balance of size vs visible quality.
Our default is High Quality. If you're shrinking phone photos to email or post online, you'll rarely need stronger. Drop a level when you need a hard size budget; raise it when the image will be printed or zoomed.
PNGs are special. The level slider only changes JPEG/HEIC quality. For PNGs, Melt does something better — it checks every pixel and, if the image is fully opaque, writes a 24-bit PNG instead of 32-bit RGBA. That single trick saves ~25% on most opaque screenshots.
Below the mode picker is a Scale slider that runs from 10% to 100%. Set it to anything below 100 and Melt resamples every image proportionally before encoding.
The options panel — mode at the top, then the compression list, the scale slider, and the output toggle.
Two things to know about scale:
At the bottom of the options panel is the Output toggle. Two choices:
The output overwrites the source file. The new file gets the same name and lives in the same folder. Useful when you're cleaning out a folder and don't need the originals afterwards.
Output lands next to the original with a suffix appended —
my-photo becomes my-photo-melted.jpg. The
suffix is editable in Settings; default is -melted.
Melt never makes a file bigger. If the re-encoded output is somehow larger than the source (it occasionally happens on tiny PNGs or already-optimised JPEGs), Melt throws the new file away and keeps the original untouched. Worst case: nothing changes.
The exception is when you've explicitly asked for a transformation — Convert mode or Scale below 100% — because at that point you've told Melt you want the result regardless of byte savings.
Melt reads anything macOS can decode and writes three modern formats. Below is what's supported, what to use it for, and what Melt does differently for each.
The everyday photo format. Melt re-encodes with the chosen quality and enables progressive scan, which gives a noticeably faster perceived load on the web. All EXIF, GPS, and XMP metadata is stripped unless you've imported the file specifically to preserve it elsewhere first.
Lossless, perfect for screenshots, UI assets, and anything with text. Melt does two clever things: it checks every pixel and writes a 24-bit PNG instead of 32-bit RGBA if the image is fully opaque (~25% smaller), and down-rezes 16-bit PNGs to 8-bit when colour banding wouldn't show.
Apple's modern photo format — roughly half the size of JPEG at the same visible quality. Native to iPhone since iOS 11. Choose it in Convert mode if you're archiving a folder of photos and don't need cross-platform compatibility (Windows still needs an extension to view HEIC).
Both read but not written. Animated GIFs are passed through as-is; the first frame is what gets compressed (Melt isn't a video tool). TIFF input is converted to whatever Melt's currently writing — usually JPEG or PNG.
Melt is a thin, native wrapper around Apple's ImageIO framework — the same engine Preview, Photos, and Finder use. The wins come from how it's used:
Most of what you'll tweak day-to-day lives in the right-hand panel
while Melt is running. Settings (⌘,) is for the
defaults — they apply to every new batch.
-melted; -compressed and -small are common alternatives.Where you enter and manage your license key. See the next section for what happens before you have one.
Melt updates itself in place — no App Store. The Updates tab shows the current version, lets you toggle automatic checks, and offers a manual "Check now" button.
Lifetime stats (number of images melted, bytes saved), build info, and a quick link to email support.
Melt is free for your first 25 image conversions. No timer, no nag screen, no watermark — just a small "X remaining" pill in the brand bar once you're getting close.
Past 25, you'll need a licence. Buy it once for $9.99 and it's yours forever on this Mac — no subscription. Or pick up Unlimited and you get Melt plus every other General Software app for one monthly fee.
The 25-image counter is lifetime, on this Mac. Reinstalling Melt doesn't reset it — that's by design. Buying a licence wipes the counter and unlocks unlimited use forever.
Two likely reasons: your image was already well optimised (web exports from Photoshop, recent iCloud photos), or you're on Compress mode and Melt judged the re-encoded output too close to the original to be worth keeping. Try Smaller File or drop the Scale slider.
Yes — once a file shows the green savings pill, click and drag its row to anywhere in Finder, Mail, Slack, etc. The file is real, not a reference.
Yes — every re-encode strips EXIF, GPS, and XMP. That's part of how Melt shrinks files. If you need to keep that information (camera shoot info, colour profiles), use a different tool for that step first.
Drop the folder, hit ⌘↩, and step away. The Dock icon shows
a badge with the number of active jobs. Melt finishes them in the
background; the brand bar will show the total bytes saved when you come
back.
Melt writes pasted PNG/TIFF data to your system's temp folder so it can treat it like any other source file. After compression, the result lands wherever your Output setting says — either replacing nothing (the original is the temp file) or as a new file in the same temp folder, ready to drag out.
That's everything Melt does.