Automatic captions
Auto caption generator
In short
AutoSubtitles is a free browser-based auto caption generator. It transcribes your video audio with AI, lets you edit the wording and timing, and exports either a captioned video or a subtitle file. Free to start with no signup; no install needed.
Overview
At a glance
| Best for | Adding captions to any video automatically |
|---|---|
| Input formats | MP4, MOV, WebM |
| Output | Captioned MP4, or SRT / VTT / TXT |
| Languages | 20+ with automatic detection |
| Account | Not needed to start |
| Price | Free to start |
Workflow
How it works
- 1
Upload your video
Drag and drop an MP4, MOV, or WebM file. Your video stays on your device; only the audio is sent for transcription.
- 2
Auto-generate captions
AI transcribes the audio in seconds with support for 20+ languages.
- 3
Review and edit
Fix any words, adjust timing, and split or merge lines so captions read naturally.
- 4
Export
Download a subtitle file or export a video with captions burned in.
Capabilities
Features
AI transcription built for video
Turn speech into caption text in seconds, even with accents and conversational pacing.
Editable captions
Correct wording, timing, and line breaks before you export. The AI gets you close, you keep control.
Caption styling
Apply ready-made styles or customize fonts, colors, outlines, and position.
Fast, browser-side rendering
Exports render in your browser, not on a server, so there is no upload and no render queue. Nothing to install.
Formats
Supported formats
| Video input | MP4, MOV, WebM |
|---|---|
| Captioned video output | MP4 (captions burned in) |
| Subtitle file output | SRT, VTT, TXT |
| Caption languages | 20+ (auto-detected) |
Plans
Free vs Pro
Start free, upgrade only if you need more.
| Capability | Free | Pro |
|---|---|---|
| Automatic caption generation | Yes | Yes |
| Editable text and timing | Yes | Yes |
| Export captioned video | Yes | Yes |
| HD and 4K export | No | Yes |
| Animations and word highlights | No | Yes |
| AI translation | No | Yes |
| Custom fonts | No | Yes |
| SRT, VTT and TXT download | No | Yes |
| Saved style presets | No | Yes |
Use cases
Who it's for
YouTube creators
Caption long-form videos automatically, then export hardcoded captions or a subtitle file.
Short-form editors
Add captions to TikTok, Reels, and Shorts without a heavyweight timeline tool.
Educators
Caption lessons quickly to improve accessibility without manual transcription.
No account required, start in seconds
FAQ
Frequently asked questions
Q.How do I automatically add captions to a video?
Upload your video to AutoSubtitles, let the AI generate captions, review the text, and export a captioned video or subtitle file. The whole process takes a few clicks, and no signup is required to start.
Q.Is the auto caption generator free?
Yes. You can generate, edit, and export captions for free with no signup. Pro adds HD and 4K export, animations, translation, and more.
Q.How accurate are the automatic captions?
The AI produces an accurate first draft from your audio, then you can correct any words and fine-tune the timing before exporting, so the final captions are as accurate as you need.
Q.What video formats are supported?
You can upload MP4, MOV, WebM, and most common video formats. Captioned videos export as MP4, and subtitle files export as SRT, VTT, or TXT.
Q.Does my video get uploaded to a server?
No. AutoSubtitles renders in your browser, so your video is never uploaded. Only the audio needed for transcription is sent for processing, and it is deleted immediately after. Browser-side rendering also makes exports fast, with no server render queue.
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