Short version: Concat shrank a 76 MB video to 3 MB in 3.9 seconds, and while it ran I logged every network request: 0 bytes of my video left my Mac. It's free, open source, built in Rust, and it ships its own MCP server so AI agents like Claude Code can edit video. But it's a 10-week-old beta (v0.2.9) with 200+ open issues.
▶ Full video: https://youtu.be/KWJw3RQHElU
What is Concat?
Concat is a desktop video editor that wants to replace CapCut. Everything runs on your own machine.
- Free and open source (AGPL-3.0), no account, no watermark, and the site says there is no paid tier.
- Built in Rust: about 159,000 lines, first release in September 2026.
- Runs on Mac, Windows, Linux, Android and iPhone.
- Fast growth: 14,000+ GitHub stars and about 440,000 downloads in ten weeks.
- Needs 4 GB of RAM (16 GB recommended for 4K).
The layout will feel familiar if you've used CapCut: library on the left, preview in the middle, inspector on the right, timeline at the bottom. Every panel can be swapped, split or dragged.
Price check (November 2026)
| Price | |
|---|---|
| CapCut Pro | US$19.99/month or $179.99/year |
| Concat | $0 |
Test 1: Compress a video (the one I ran myself)
Concat has free tools that run right in the browser. I tried Compress a video in Chrome on my Mac:
- Input: 76 MB stock clip, 20 seconds of 1080p H.264
- Settings: Balanced quality, 720p, MP4
- Result: 3.0 MB (96% smaller) in 3.9 seconds
It encodes on your own GPU, with no server in between. I recorded every network request during the run: 0 bytes of the video were uploaded. The honest flaw: the page still loads Google ads.
Test 2: Auto captions
Captions are one button (the T on the timeline). You pick a Whisper model; the base English one is a 148 MB download, and after that it transcribes fully offline. You get one title per phrase on the timeline, you can restyle all of them at once, and it imports and exports SRT. Their own guide has a section called "why a word is wrong", so expect to fix a few words.
Test 3: Text to speech, voice cloning, background removal
- Type a script, pick a voice, and the read lands on your timeline.
- Voice cloning from a few seconds of audio (small model 98 MB, studio model about 1 GB).
- Background removal for people or objects, plus a smart brush. The person model is 15 MB. No green screen.
- Downside: on phones, the built-in voice is still coming.
Test 4: 4K export and the MCP server
Export H.264, HEVC or AV1 up to 4K 60 fps, 10-bit, no watermark at any resolution. This week's update made 4K exports about 2.4x faster.
The part developers will care about: Concat ships its own MCP server. An AI agent like Claude Code gets tools for clips, titles, keyframes, effects and export, the same commands the editor itself uses. Setup is one line in the terminal; the steps are in the repo's docs/MCP.md.
So "cut the silences, add captions, export 1080p" can be a prompt instead of an afternoon.
The catch
- Beta: v0.2.9 with 200+ open issues on GitHub.
- Windows builds aren't code-signed yet, so SmartScreen will warn you.
- Phones: no built-in voice yet.
Verdict
If you edit for clients with deadlines, not yet. If you're a student, a Linux user, a small creator, or a developer who wants an editor an agent can drive, it's already useful, and it's free. Nothing uploads, which also makes it a good fit for private footage.
Would you let an AI agent cut your videos through MCP? I'm curious what you'd automate first.
Links
- Concat website + download: https://concat.standalones.org
- Source code: https://github.com/jub0t/Concat
- MCP setup: https://github.com/jub0t/Concat/blob/main/docs/MCP.md
- Full video: https://youtu.be/KWJw3RQHElU
AI-assisted disclosure: I used an AI assistant to help structure this write-up. The compression test, timing and network log are my own (Chrome on my Mac, November 6, 2026). Feature details come from Concat's site, docs and GitHub repo. Not sponsored by Concat or CapCut.
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