AI Caption & Subtitle Generator
Auto-generate synchronized subtitles, drag captions anywhere over your video, and style them with 33 trending presets plus a Canva-style color palette.
Runs directly inside your browser · No files uploaded to servers
Free AI Caption & Subtitle Generator
Generate 1-word karaoke captions, short 2-3 word phrases, or full sentences. Style them with 33 trending presets — Business, Retro, Bold, Elegant and Minimal — custom colors, and drag subtitles anywhere on your video.
How to Generate Captions Online — 3 Easy Steps
No subscription, no upload limits, and no server leaks.
- 01
Drag & Drop Audio or Video
Drop any audio clip (MP3, WAV, AAC, M4A) or video recording (MP4, MOV, WebM). The audio track is processed directly inside your browser.
- 02
Pick a Style & Customize
Choose from 33 caption presets across Business, Retro, Bold, Elegant and Minimal. Fine-tune size, colors and word pacing, then drag the subtitle anywhere on the canvas.
- 03
Edit, Preview & Download
Scrub the caption timeline, fix any word in the Edit tab, preview synchronized captions in real time, and download .SRT, .VTT, .TXT, or export a video with burned-in captions.
Why Use LuminaAudio's AI Caption Generator?
Private, instantaneous, and designed specifically for creators.
Frame-Accurate Synchronization
High-precision word boundary recognition ensures every subtitle cue appears with tight vocal alignment.
Drag & Position Anywhere
Click and drag captions freely anywhere on top of your video with smooth pointer tracking.
33 Caption Style Presets
Business, Retro, Bold, Elegant and Minimal looks — one click each, live preview on every card.
Dual-Tone Color Control
Independently pick text and accent colors — both are always separately editable with native color pickers and quick-select swatches.
100% Private On-Device
All recognition runs locally inside your browser memory. Your recordings never leave your device.
Scrollable Editable Timeline
Zoom the timeline, drag caption edges with the two-sided handles to trim timing, drag bodies to shift, and click a block to seek.
MP4 Video Export
Export your video with captions burned directly into the frame — styled exactly as you see in the preview.
SRT, VTT & TXT Exports
Export industry-standard SubRip (.SRT) and WebVTT (.VTT) formats with precise millisecond timestamps.
Frequently Asked Questions
Everything you need to know about styling and generating synchronized captions.