Your photos shouldn't ride the elevator to a stranger's data centre

Think of the last time this week you needed to convert a media file: a HEIC photo to JPG, a video compressed for Slack, two PDFs merged, a screen recording’s audio pulled out into its own file.

Most people use a free online converter for that. You upload the file to cloudconvert.com or ilovepdf.com or tinypng.com or one of a hundred near-identical sites, wait, download the result, and move on. The same reflex reaches documents with your home address printed on them, vet paperwork, for one.

Almost none of those tools needed your file to leave your device. Uploading is convenient, but it sends private files somewhere they never needed to go, and MediaKit is the studio’s argument that the whole category of conversion tools belongs on your Mac and iPhone.

What does “convert online” actually do to your file?

When you use a free online converter, the file goes through these steps:

1. It leaves your machine, encrypted in transit.
2. It lands on the operator’s storage, sometimes encrypted at rest, sometimes not.
3. Their conversion pipeline processes it, which typically takes seconds.
4. It is held in storage, often for hours, sometimes for days, depending on the operator’s retention policy.
5. You download it.
6. It may or may not be deleted from the operator’s storage according to their stated policy, which you have no way to verify.

You notice the first and last steps. The privacy questions sit in the middle ones. The file you converted contained whatever it contained (a photograph of your kitchen, a screenshot of an email, a PDF of your medical records, a video of your child), and it now lives, briefly or not so briefly, on infrastructure you do not control.

Most online converters are run by small teams, and most try to delete files promptly. The problem is the design: files leave your machine for processing that doesn’t require it, and you have to trust the operator to be careful in the right way.

Apple Silicon changed the math

Cloud converters dominated because local conversion used to be slow. Ten years ago, compressing a 4K video on a laptop could take longer than uploading it to a cloud service and waiting for the result.

Apple Silicon closed that gap. Modern Macs have hardware video encoders on the chip, with ProRes acceleration and HEVC encoding built in. Local performance is now competitive with the cloud round trip.

For images and PDFs, local processing was always faster. Those moved to the cloud because web tools are easier to ship: one runs in any browser, while a desktop tool has to be installed. That is real friction, and we think the privacy you keep is worth it.

What MediaKit specifically does

MediaKit is a Mac and iPhone app with more than 150 local tools, organised by kind of file:

• Video: compression to a quality, a target size, or a bitrate, conversion with H.264 or HEVC and ProRes written to .mov, resolution changes, frame extraction, and audio extraction.
• Image: conversion between HEIC, JPG, PNG, and WebP (where your system can write it), batches with Pro, resize, crop, and rotate, and metadata stripping.
• Audio: conversion to M4A (AAC), WAV, AIFF, ALAC, or CAF, sample rate and channel changes, and silence removal.
• PDF: merge, split, redact, sign, OCR, page reorder, compress.
• Archive: create ZIP, TAR, GZIP, XZ, and BZIP2 archives, and extract those plus RAR4 and RAR5. RAR archives still turn up in 2026, and MediaKit opens them on the device.

Every tool runs entirely on your Mac or iPhone, so nothing is uploaded and there is no operator retention policy to read. For the most common video job, getting a clip under an email attachment limit, the limits and the bitrate arithmetic are in a separate guide.

On Mac, six MediaKit actions appear in Shortcuts (Compress Video, Convert Image, Compress Image, Merge PDFs, Create ZIP, and Extract Text from Image), so you can chain them into your own workflows. With Pro, Folder Automation goes one step further: “compress every video that lands in this folder” becomes a saved Recipe that runs on its own, and it never touches the internet.

The freemium decision

Pricing was the decision we argued about most before launch.

MediaKit shipped with five tools that stay free for good (Video Compress, Image Compress, Image Resize, Audio Convert, and PDF Compress), which between them cover most casual use, and a single Pro tier that unlocks every other tool and batch processing across all of them. For the first 3 days every tool works, one export per run, so you can try everything before deciding.

We wanted a free path that people would actually use. Five tools is enough that a casual user could go years without paying, and that’s fine; the app should be useful first.

The long tail of tools is what makes MediaKit worth paying for to a power user, and power users are the ones who fund building it. So power users pay because they get a lot out of the app, and casual users pay nothing for the basics.

In short

If you habitually use online converters, MediaKit is our case that you don’t need to. The Mac or iPhone in front of you can do the same processing locally, and your files stay on it.

The free tier covers the common cases. The Pro unlock covers everything else, including the less common jobs (RAR5 extraction, stripping metadata from a batch of photos, PDF redaction) that online services handle by taking your file away first.

It’s the last weekend of March. If you have a stack of media files you’ve been meaning to process, this is a way to do it without uploading any of them.