Coming soon
Too big to send? Name a size and it lands under it.
- macOS Sequoia | Tahoe | Golden Gate
- Free
- Repack, instantlyMOV becomes MP4 without touching a frame.
- Convert, properlyContainer, codec, resolution, bitrate.
- Fit under a limitType a size, or tap a preset.
- Built for batchesDrop a folder in; override any file.
- Stays on your MacNo uploads, no accounts, no tracking.
Questions
- Yes — free on the Mac App Store. No subscription, no in-app purchases, no account.
- Repack only changes the container: your .mov becomes an .mp4 with the video and audio streams copied across exactly as they are. Same quality, same resolution, same bitrate, done in seconds — that's what you want when the size was never the problem. Convert re-encodes, for when it is. And if you pick Convert but ask for exactly what the source already is, the app quietly repacks instead, rather than spending a generation of quality to make a worse copy of the same thing.
- You type the size you need and Undersize works backwards from it: how long the clip is, how much the container itself costs, and what bitrate fits in what's left. That overhead is measured from your own file instead of assumed, so a 25 MB target lands under 25 MB and not slightly over. If the file already fits, it's left alone — a target is a ceiling, not a quota, and re-encoding can't restore detail the source never had.
- No, and it isn't planned. Undersize is built entirely on Apple's own video frameworks, which don't read or write those containers. The usual workaround is to bundle ffmpeg, but its licence can't be reconciled with App Store distribution — so the app does the formats macOS handles natively, and says so rather than failing on them quietly.
- Never. Everything happens on your Mac, through the same video frameworks the system itself uses and the hardware encoder in your machine. There are no servers, no accounts, and nothing is collected or tracked.
- macOS Sequoia 15 and Tahoe 26 — support for macOS 27 is expected after its stable release. Universal binary, native on Apple Silicon and Intel.