ComfyUIOpenCut

If you dragged a ComfyUIOpenCut node onto the canvas expecting it to do something to a video, the empty sockets will probably confuse you. That's because the node is a lie - and a useful one. It has no inputs, no outputs, and runs nothing. The whole point of this pack is the button it adds to ComfyUI's top menu, which opens OpenCut, a full multi-track video editor that lives entirely in your browser at http://127.0.0.1:8188/opencut/.

Why would you want that inside ComfyUI? Because the gap between "I generated 40 clips" and "I have a finished MP4" is a real workflow problem, and normally you'd hop to CapCut, Premiere, or DaVinci to close it. OpenCut is a professional-enough timeline editor (tracks, trimming, transitions, keyframes, audio waveforms) that runs on your own machine, so your generated footage never gets uploaded anywhere to be edited. For privacy-sensitive or client work, that's the pitch, and it's real: everything happens client-side.

How it actually works

The mechanism matters because it explains why this pack is weird. The Python side is almost nothing: the __init__.py registers two aiohttp routes that serve a prebuilt static site (opencut-ui/, a Next.js build, ~66MB, shipped inside the repo) at /opencut. A bundled JavaScript extension then adds an OpenCut button to ComfyUI's top menu (next to settings), which opens that page in a fullscreen iframe. That's the entire integration.

The editor itself is the OpenCut open-source project, embedded wholesale. Rendering moved to a Rust/WASM GPU renderer (with WebGL fallback while WebGPU stabilizes), video processing is FFmpeg.wasm, and projects autosave to IndexedDB/OPFS - large files land in Origin Private File System so you're not blowing up browser storage. None of this touches your Python environment, which is why the pack has zero Python dependencies.

The node you'll never use

Per its schema, ComfyUIOpenCut is an output node with an empty required, empty optional, and no RETURN_TYPES. It returns nothing. It exists purely so the pack registers as a custom node. So: don't build a workflow around it. Drop it on the canvas if you want a visual reminder that the editor exists, or skip it entirely and click the button or hit the URL. It doesn't interact with your samplers, your CLIP, or your VAE - it's a launcher, not a data node.

Installing it

The easy way is ComfyUI Manager: search for "OpenCut" or "ComfyUI-OpenCut" and install. Manually:

cd /path/to/ComfyUI/custom_nodes
git clone https://github.com/jtydhr88/ComfyUI-OpenCut.git
# no pip install needed - pyproject.toml declares zero dependencies

Then restart ComfyUI. The top-menu button needs ComfyUI Frontend v1.24.4+; if you're on an older frontend, the direct URL http://127.0.0.1:8188/opencut/ still works. You do need a modern browser - WebAssembly is mandatory, SharedArrayBuffer is recommended, and the README suggests at least 4GB RAM. This is one of the rare custom nodes that installs cleanly with no dependency hell - the thing the ecosystem is famous for (see the LLMVISION incident and the endless "missing node" posts) simply doesn't apply when there's nothing to import.

What bites people

The README's own troubleshooting is a good map. Playback stuttering on large files → lower the preview resolution or close other tabs; it's doing real decode in your browser. Export failing → check browser storage space, try lower resolution/quality, verify the media isn't corrupt. Media not loading → check the browser console (F12) and refresh. The pack is under active development and was recently rebased onto ~8 months of upstream OpenCut work, so expect rough edges and occasional changes - it's not battle-tested at Premiere scale, and if you hit an editor bug, the OpenCut upstream repo is the right place to report it.

Honestly, if your ComfyUI work is mostly image gen and you never assemble video, you don't need this. But if you're churning out animated generations and want to cut them into something shareable without leaving your machine, it's a genuinely neat toy that costs you a clone and zero dependencies.