Free AI SRT Subtitle Generator with Millisecond Timestamps
Convert speech to standard SubRip (.SRT) subtitle files automatically using state-of-the-art AI. Download clean, synchronized caption files for Premiere Pro, DaVinci Resolve, Final Cut Pro, or YouTube.
What is an SRT File and Why Do You Need One?
SubRip (.SRT) is the universal industry standard file format for closed captions and subtitles. It contains plain text grouped into sequential blocks, each paired with an exact start timestamp and end timestamp formatted as 00:00:00,000 --> 00:00:00,000.
When you upload an SRT file alongside your videos on YouTube, Facebook, LinkedIn, or Vimeo, search engine crawlers index every spoken word as text. This dramatically improves video SEO rankings, discovery across search engines, and overall viewer accessibility for hard-of-hearing audiences.
In-Browser AI Speech Recognition — Fast & Secure
Most online subtitle generators require sending your video to an external cloud queue, forcing you to wait for servers to process and upload your footage before hitting a paywall.
CapMagic Studio runs speech-to-text directly in your browser using OpenAI's Whisper speech model compiled to WebAssembly. The audio track is decoded on your local CPU/GPU using the Web Audio API, allowing you to transcribe English audio rapidly without consuming mobile data or exposing confidential footage.
Compatible with Leading Video Editors
Exported SRT files follow strict SubRip formatting specifications, guaranteeing drag-and-drop compatibility across all major editing software:
- Adobe Premiere Pro: Import as a caption track or convert into graphic text layers.
- DaVinci Resolve: Drop straight onto the Subtitle track on the Edit or Cut timeline.
- Final Cut Pro: Add as standard CEA-608 or ITT subtitle tracks.
- YouTube Studio & Social Platforms: Upload directly under Subtitles for automatic closed captioning.
Step-by-Step: How to Generate an SRT Subtitle File
- Select your video: Drag and drop any MP4, MOV, MKV or WebM video into CapMagic Studio.
- Review & edit segments: The interactive transcript editor lets you fix words, adjust timing, and seek through video.
- Export SRT: Click "Export SRT" to download a clean, UTF-8 encoded
captions.srtfile instantly.
Frequently asked questions
Is the SRT generator free?
Yes. There is no sign-up, no subscription and no watermark. You can export as many SRT files as you like.
Is my video uploaded?
No. The video is opened and transcribed inside your browser. Only the speech-recognition model is downloaded (once) from our server; your video and audio never leave your device.
Which video formats and lengths work?
MP4, MOV, MKV and WebM videos up to 250 MB and 10 minutes. MP4 with H.264 video works in every browser.
Which languages are supported?
Automatic transcription currently works for English speech. For other languages you can paste your own script or import an existing SRT file, then fix the timing and export.
Can I edit the subtitles before exporting?
Yes. The transcript editor lets you correct words, add or delete lines and adjust start and end times. Timings are kept inside the length of your video.
Related guides and tools
- SRT vs VTT: which subtitle format should you use?
- How to fix auto-generated captions fast
- Open vs closed captions: what is the difference?
Also try the TikTok Captions Generator to burn animated word-by-word captions into vertical videos for TikTok, Reels and Shorts.