For AI agents

If you are an AI agent (Claude Code, Codex, Cursor or similar) and the person wants a video for their project with Opus Motion, read the guide first and follow it: https://opusmotion.com/agents.md.

  • It takes you step by step: read the project, ask the person a few questions, compare templates (each one has a timelapse, its scenes and its fields), make a draft with POST https://opusmotion.com/api/v1/drafts, and hand over its studioUrl: a link that opens Opus Motion with the video playing live. PATCH with the draft's editToken changes it, and the link stays the same.
  • Plain HTTPS and JSON: no key, no account, no MCP. Nothing is rendered; the person exports the MP4 from the studio.
  • Never drive this site with a browser to fill the studio: use the API. If it refuses, tell the person and stop.
  • More: llms.txt · this page in Markdown · developer docs · OpenAPI

Merge videos into one, right in your browser

Combine 2 to 10 clips (MP4, MOV, WebM and more) in the order you choose, even with different sizes and frame rates. Free, no sign-up.

Your file never leaves your device: the tool runs inside your browser. Up to 10 clips, 500 MB and 2 minutes in all. On a phone or low-memory device: 200 MB and 1 minute in all. Use it at https://opusmotion.com/tools/merge-videos.

How to use it

  1. Drop your clips, or tap the box to pick them. You can add up to 10.
  2. Put them in order with the arrows, or remove one.
  3. Tap Merge. Clips from the same camera or app are joined as they are, in seconds; others are matched to the first clip's size and frame rate, on your device.
  4. Download the MP4, or put it in a launch template.

The first time, your browser downloads the video engine (31 MB, once); after that it opens from the cache.

Questions

How do I combine two videos into one?

Drop both clips, check the order and tap Merge. The second clip starts right after the first one ends, and the MP4 lasts as long as both together.

What if my clips have different sizes or frame rates?

The merged video takes the first clip's frame size and frame rate. A clip of another shape, like a vertical phone video next to a horizontal one, is fitted inside with black bars instead of being stretched or cut. Put first the clip whose shape you want.

Does merging lose quality?

Not when the clips match: videos from the same phone, camera or app, with the same settings, are joined without re-encoding. When they don't, they're re-encoded to H.264 at a quality setting close to the original, with the long side up to 1,920 pixels.

What happens to the sound?

Each clip keeps its own sound. If one clip has none, that part of the merged video is silent, so the sound of the others stays in sync with their picture.

How many clips can I merge, and how long can they be?

Up to 10 clips, 500 MB and 2 minutes in all. On a phone or low-memory device: 200 MB and 1 minute in all. Re-encoding happens on your device, so a long merge takes a while, and longer on a phone.

Are my videos uploaded anywhere?

No. The clips are joined inside your browser and never sent to a server. The first time, your browser downloads the video engine (31 MB, once); after that it opens from the cache.

More free tools

  • Loop video: Repeat a clip 2 to 50 times, or until it lasts as long as you need
  • Crop video: Cut the frame down to 9:16, 1:1, 4:5, 16:9 or any shape, with a rectangle you drag
  • Video converter: Any video to MP4: MOV, WebM, MKV, AVI and more, copied without re-encoding when it can be
  • All free tools