Free AI caption generator · 100% in your browser

Video Caption Generator , animated, word-by-word

This AI caption generator transcribes your video automatically, then each word pops on screen one at a time, timed to match your voice. A true auto caption generator, short-form style.

How to generate animated captions

1
Import your video
Drop your file. It stays on your device, nothing is uploaded.
2
Generate captions
Click “Generate captions”. Montaj transcribes the audio with AI, splits it into individual words, then burns each one onto the picture in sync.
3
Get your MP4
Save the video with animated captions burned in, ready to post.

Frequently asked questions

How do I add animated captions to a video for free?

Import your video and click “Generate captions”. The audio is transcribed, split into individual words, and each one is burned onto the picture one at a time, entirely in your browser.

Is my video uploaded to a server?

No. Transcription and caption burn-in both run on-device with Whisper and ffmpeg.wasm. Your video is never uploaded.

Why one word at a time instead of full lines?

It's the popular short-form caption style (TikTok, Reels, Shorts). Punchy and easy to read at a glance. For full timed lines instead, use the Subtitle generator tool.

Which languages are supported?

Auto-detect, English, French, Spanish, German, Italian and Portuguese.

What if my video has no speech?

The tool tells you no speech was detected. There's nothing to caption without a voice track.