AI Auto-Captions Online
Add accurate AI-generated captions and subtitles to videos — entirely in your browser.
Loading Speech Recognition AI
Downloading AI model (~~40 MB). This only happens once — the model is cached for future use.
Initializing...
The AI model runs entirely in your browser. No files are uploaded to any server.
What Are AI Auto-Captions?
AI Auto-Captions is a free online tool that add accurate AI-generated captions and subtitles to videos — entirely in your browser. No files are uploaded — everything is processed locally on your device.
AI auto-captions use speech recognition technology to automatically generate subtitles for your videos. The AI model (Whisper) runs entirely in your browser, transcribing speech to text with timestamps and producing an SRT subtitle file. This is essential for social media videos, accessibility compliance, content repurposing, and reaching viewers who watch with sound off. Your video is processed locally — it is never uploaded to any server.
Privacy guarantee: AI Auto-Captions processes all files directly in your browser using WebAssembly. No data is uploaded to any server, no information is collected, and the tool works offline after loading. Unlimited usage with no signup, no watermarks, and no file size limits.
How to Use AI Auto-Captions
Upload your video
Select a video file from your device. The tool accepts MP4, WebM, and other common video formats.
Generate captions
Click Generate Captions. The AI model processes the audio track and creates timestamped subtitles.
Download SRT file
Review the generated captions, make any edits, then download the SRT subtitle file.
Why Use Our AI Auto-Captions?
Frequently Asked Questions
How accurate are the AI-generated captions?
The Whisper AI model provides high accuracy for clear speech in supported languages. Accuracy may decrease with heavy accents, background noise, or multiple overlapping speakers. You can edit the output before downloading.
What languages are supported?
The default model supports English. For other languages, a multilingual model option is available which supports 50+ languages including Spanish, French, German, Chinese, Japanese, and more.
Can I edit the generated captions?
Yes. After generation, the captions appear in an editable text area. You can fix any errors, adjust timing, or modify text before downloading the SRT file.
Does this upload my video to a server?
No. The AI model downloads once and runs entirely in your browser. Your video audio is processed locally on your device and is never transmitted anywhere.
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