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

Resize video for any platform, and keep all of it

Horizontal to vertical and back: 16:9, 9:16, 1:1 or 4:5, on a blurred background, on your color, or cropped to fill. MP4, MOV, WebM and more. Free, no sign-up.

Your file never leaves your device: the tool runs inside your browser. Up to 500 MB and 2 minutes. Use it at https://opusmotion.com/tools/resize-video.

How to use it

  1. Pick the new shape: 9:16 for Reels, TikTok and Shorts, 1:1 or 4:5 for feed posts, 16:9 for YouTube.
  2. Choose Fit to keep the whole picture on a blurred or colored background, or Fill to crop it to the new shape.
  3. Drop your video, or tap the box to pick it. It's resized on your device, with its sound.
  4. Download the MP4, or put the clip 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 change a video's aspect ratio without cropping it?

Choose Fit: the whole video is scaled to fit the new shape, and the space around it is filled with a blurred copy of the video or a color you pick. Nothing is cut away.

How do I make a horizontal video vertical?

Pick 9:16. With Fit, the horizontal video sits in the middle with a background above and below it; with Fill, it's cropped to its center so it fills the whole vertical frame.

What size does the video come out at?

16:9 comes out at 1920 × 1080, 9:16 at 1080 × 1920, 1:1 at 1080 × 1080 and 4:5 at 1080 × 1350: the full-quality sizes the social platforms take.

Can I use my brand color as the background?

Yes: pick any color for the background. If you've pasted your website on Opus Motion, your brand's color shows up as one of the options.

How long can the video be?

Up to 2 minutes and 500 MB. On a phone or low-memory device: 1 minute and 200 MB. It's encoded on your device, so a long video takes a while, and longer on a phone.

Is my video uploaded anywhere?

No. It's resized 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

  • Crop video: Cut the frame down to 9:16, 1:1, 4:5, 16:9 or any shape, with a rectangle you drag
  • Merge videos: Join two or more clips into one MP4, in the order you choose
  • Loop video: Repeat a clip 2 to 50 times, or until it lasts as long as you need
  • All free tools