You Google “convert HEIC to JPG.” The first result is a free online tool. You drag your photos in, click convert, download the results. It works. But in the thirty seconds between upload and download, your photos sat on someone else’s server, processed by software you can’t inspect, governed by a privacy policy you didn’t read.

I thought about this when I was building Picmal. I had been using online converters for years without a second thought. Then one day I uploaded a batch of screenshots that included a client’s dashboard. Full names, revenue numbers, everything. The converter worked fine. But those images went somewhere, and I had no idea where.

That was the moment I decided the tool I was building had to be entirely offline.

The real problem with online converters

Most online converters are free because your files are the product. Not all of them are malicious, but the business model doesn’t reward protecting your privacy.

Here’s what happens when you upload:

  • Your files land on a server you don’t control. Most services say they delete after an hour. Some say 24 hours. Some say nothing.
  • EXIF data tags along. GPS coordinates, device model, timestamps. All embedded in the file, all transmitted unless explicitly stripped.
  • Terms of service are suspiciously broad. I’ve read a few. Some grant themselves a licence to use uploaded content for “service improvement.” Nobody defines what that means.
  • GDPR makes this your liability. If you’re a freelancer or agency handling client images, uploading them to a random converter might violate your data processing obligations. Nobody thinks about this until a client asks.

None of this matters if you’re converting a meme. All of it matters if you’re converting photos of someone’s kids, scanned contracts, medical images, or anything under NDA.

Every offline method on Mac

Every way to convert images without a single byte leaving your machine.

1. Picmal

This is the tool I built, so I’m biased. But I built it specifically because the alternatives below all have gaps.

Picmal is a native Mac app. You drag files in, pick a format, and convert. Everything happens locally. It handles batch conversion, preserves metadata, and supports formats that online tools usually don’t: HEIC, HEIF, AVIF, TIFF, WebP, alongside the usual JPG, PNG, GIF, and BMP.

It costs $15.99, one time. No subscription, no account, no internet connection required.

I use it for my own work daily, and it handles hundreds of files without slowing down. If you need something that just works for batch jobs, this is what I’d recommend.

2. macOS Preview

Open an image in Preview. Go to File > Export. Choose a format from the dropdown. Save.

This works perfectly for one file. The problem is that it’s one file. Fifty images means fifty trips through File > Export. Preview also can’t export to AVIF or WebP, which rules it out for modern web work.

Good for a one-off. Tedious for anything else.

3. Quick Actions in Finder

Since macOS Monterey, you can right-click images in Finder, go to Quick Actions > Convert Image, and pick a format. You can select multiple files, which makes it better than Preview for small batches.

The downsides: limited formats (JPG, PNG, HEIF only), no quality control, no AVIF or WebP. Gets sluggish with larger selections. But for 5-10 images in standard formats, it’s genuinely useful and requires installing nothing.

4. Automator

Automator lets you build a conversion workflow that runs as a Folder Action or a Quick Action. You can set it up to automatically convert any image dropped into a specific folder.

The setup isn’t trivial. You configure input format, output format, destination folder, naming convention. If you get the destination wrong, Automator will happily overwrite your originals. I learned this the hard way. There’s no undo.

Once it’s working, it keeps working. But the setup cost only pays off if you’re converting images on a recurring basis. For a one-time batch, you’ll spend more time configuring than converting.

5. ImageMagick via Terminal

If you’re comfortable with the command line, ImageMagick is the most powerful option. Install it via Homebrew:

brew install imagemagick

Then convert a single file:

magick input.heic output.jpg

Or batch convert every HEIC in a folder:

magick mogrify -format jpg *.heic

ImageMagick supports nearly every image format that exists. The trade-off is obvious: you need Homebrew, you need to be comfortable in Terminal, and you get zero visual feedback. If you don’t already live in the command line, this isn’t where you start.

When does offline actually matter?

Honestly? It always matters. You just don’t feel it until the stakes are high.

  • Client work. Those files aren’t yours to upload to a random server.
  • Legal and medical documents. Scanned pages with embedded images can contain information subject to regulation.
  • Children’s photos. Parents send HEIC photos to relatives. Grandma needs JPGs. The photos end up on a free converter. Nobody in that chain stopped to ask where they went.
  • Anything under NDA. Screenshots, mockups, pre-launch product photos. An online converter technically counts as sharing with a third party.

For professional work, offline conversion isn’t a nice-to-have. It’s a requirement most people don’t realize they have until someone asks.

Why this is still a problem

“Convert image online free” gets millions of searches every month. That tells you everything about the state of native tools. Apple ships Quick Actions and Preview, but both are limited enough that people reach for the browser anyway. Most users don’t know Automator exists. Nobody installs Homebrew to convert a photo.

Offline should be the default, not something you hunt for. When most people’s first instinct is to upload their files to a stranger’s server, the native tools have failed at something basic.

That’s why I built Picmal. Not because the world needed another converter, but because the converters people actually use ask them to give up something they shouldn’t have to.