ShrinkMasterv0.1
macOS · 11+ · universal · MIT
Just videos.
Made smaller.
A free, native Mac app that shrinks videos by 70–90% using H.265 or AV1. Hardware accelerated. 100% local. Nothing leaves your machine.
Made by @kellyyuweipeng — follow on X →
~/Movies/iphone-vacation-4k.mov
● compressing
size after H.265
1.4 GB
182MB
−87.0% · 1.22 GB saved
codecH.265 (HEVC)
encoderVideoToolbox
resolution3840×2160 → kept
bitrate48 Mbps → 6.2 Mbps
presetquality 28
durationkept · re-encoded
* representative output, MacBook Pro M2, default settings
▎ The headline number
Same video. A fraction of the size.
Real outputs from H.265 at quality 28. Visually indistinguishable from the source, without the storage tax.
file
before
after
codec · profile
saved
iphone-vacation-4k.mov
4K HDR · 60fps
1.4 GB
182 MB
H.265
−87%
screen-recording.mp4
1440p · 30fps
820 MB
94 MB
H.265
−89%
drone-footage.mov
4K · 24fps
3.2 GB
410 MB
AV1
−88%
wedding-clip.mov
4K · 60fps
5.8 GB
720 MB
H.265
−88%
tutorial.mp4
1080p · 30fps
640 MB
78 MB
H.265
−88%
gameplay.mkv
1440p · 144fps
2.1 GB
260 MB
AV1
−88%
▎ What it does
Built for the way Mac users actually work.
01
100% on-device
Your files never touch a server. No upload, no account, no telemetry, ever. Works offline.
02
70–90% smaller
Modern codecs do the heavy lifting. H.265 by default, AV1 when you need the absolute smallest files.
03
Drop a folder, walk away
Batch processes the whole queue while you do something else. Pick up where you left off.
04
Hardware accelerated
VideoToolbox on Apple Silicon. NVENC / QSV / AMF on the rare Mac that has them. Falls back to CPU.
05
Free. Forever.
Open source. No paid tier. No 'pro' features behind a paywall. The whole thing is on GitHub.
06
Native Mac app
Real .app, not a web wrapper pretending. Drag-drop, sheets, keyboard shortcuts. The whole deal.
▎ Where it shines
For the moments your hard drive hates.
Discord / Slack
Sharing in chat
Get under the 25 MB upload limit without an awkward link to Google Drive.
Social posts
Posting to social
Trim a 4K phone clip down to something Twitter, Bluesky, or your blog will actually accept.
Archive
Long-term archive
Years of phone footage, condensed. Looks the same, takes a tenth of the space.
Email / iMessage
Sending to family
Make grandma's birthday clip small enough to actually send, large enough to actually watch.
▎ How it compares
Why not just use something else?
ShrinkMaster
Online tools
HandBrake
Paid Mac apps
100% local
✓
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Free
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partial
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Drag & drop a folder
✓
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Hardware accelerated
✓
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AV1 encoder included
✓
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Not a subscription
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Native Mac UI
✓
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▎ The app
One window. One ring.
One smaller file.
ShrinkMaster
Advanced
+ Add files
✓
Done · saved 1.22 GB
1.4 GB → 182 MB · 87% smaller
Builder · Author · Creator
Kelly Peng
I built ShrinkMaster because I have a lot of video files over 10 GB. They won't fit in email. Uploading them anywhere takes forever. And keeping them eats through expensive hard drives. So I built it for myself.
▎ The developer
Made by an indie developer.
ShrinkMaster is one of several tools I'm building. If you'd like to follow what I'm working on, I'm @kellyyuweipeng on X.
▎ Common questions
Things people ask.
Q01Is it really free?
Yes. Free download, free to use, free forever. The whole codebase is on GitHub. There's no paid tier, no upsell, no 'pro' version. If that ever changes, the existing version stays free.
Q02macOS says the developer can't be verified. What do I do?
ShrinkMaster isn't signed with an Apple Developer ID yet (those cost $99/year). The fix is one-time: drag the app to Applications, then right-click → Open instead of double-clicking. After that, it launches normally.
Q03Does my video get uploaded somewhere?
No. Encoding happens entirely on your Mac via a bundled ffmpeg binary. The app makes no network requests during compression. You can verify in Activity Monitor. The source is public.
Q04H.265 vs AV1: which should I pick?
H.265 for almost everything. Fast, near-universal playback, great quality. AV1 for cases where you need the absolute smallest file and don't mind it taking longer. Both ship with the app.
Q05Will it run on my older Mac?
Anything macOS 11 (Big Sur) or later. The release is a universal binary. Runs natively on Intel and Apple Silicon. Hardware encoding is automatic when available; otherwise CPU still gets the job done.
Q06Windows or Linux build?
Mac-only for now. The project is built on Electron + ffmpeg, so cross-platform is technically straightforward, but I want to ship one platform really well first.
Ready to free up some hard drive?
Universal Mac app, ~80 MB. Big Sur or later. Drop a video, get one back, smaller.
$ curl -L github.com/kellypeng/shrinkmaster/releases/latest