Subtitle Burner
Permanently burn SRT or VTT subtitles into any video — no sign-up, no uploads, nothing to install. Pick your font size, color, and position, then download your video in seconds. Everything runs right in your browser.
Drop a video file here
MP4, WebM, MOV, AVI, MKV — up to 500 MB
How It Works
Choose your video
Drop any MP4, WebM, MOV, AVI, or MKV file. It loads directly into your browser — nothing leaves your computer.
Add subtitle file
Drop an SRT or VTT subtitle file. VTT is automatically converted to SRT in your browser before processing.
Pick your style
Set font size (S/M/L), color (White or Yellow), and position (Bottom or Top). Settings are passed directly to FFmpeg's ASS subtitle renderer.
Burn & download
FFmpeg WebAssembly bakes the subtitle text into each video frame and copies the audio without re-encoding. Your MP4 saves straight to your device.
Your video and subtitles stay on your device
Unlike cloud-based subtitle tools, this tool never transmits your video or subtitle file to a server. All rendering happens inside your browser tab using FFmpeg compiled to WebAssembly. FFmpeg is the same open-source engine that powers professional video editors and streaming platforms worldwide — here it runs entirely on your CPU inside a sandboxed browser environment. You can confirm this by watching your network tab in DevTools during processing: you will see zero outbound video requests.
Hard subtitles vs. soft subtitles
This tool creates hard subtitles (also called burned-in, baked-in, or open captions). The subtitle text is permanently drawn onto each video frame, so it is always visible regardless of the player, device, or platform. This is the format required for most social media platforms and for sharing video clips where you cannot control the viewing environment. Soft subtitles, by contrast, are stored as a separate track inside the video container and can be toggled on or off — but require a compatible player that supports subtitle tracks.
Common uses for burned-in subtitles
- Adding captions to social media clips (Instagram Reels, TikTok, LinkedIn) where autoplay is muted by default.
- Creating accessible versions of video tutorials or course content.
- Embedding translated subtitles into a video for distribution in a specific region.
- Archiving a video with its subtitle track permanently attached.
- Submitting video content to platforms that do not support separate subtitle tracks.
Supported subtitle formats
SRT (SubRip Text) is the most widely supported subtitle format. Each cue block contains a sequence number, a start and end timestamp in HH:MM:SS,mmm format, and one or more lines of text. WebVTT is the web standard for HTML5 video subtitles and adds support for cue positioning, styling with CSS, and chapter markers. Both formats are accepted — VTT files are automatically converted to SRT in your browser before being passed to FFmpeg.
Frequently Asked Questions
Is my video uploaded to a server?
No. All processing happens locally in your browser using FFmpeg WebAssembly. Your video and subtitle files never leave your device — nothing is transmitted to any server.
What subtitle formats are supported?
SRT (.srt) and WebVTT (.vtt) files are supported. VTT files are automatically converted to SRT format in your browser before processing — no manual conversion needed.
What is the difference between hard and soft subtitles?
Hard subtitles are permanently burned into the video frames and always appear on every device and player. Soft subtitles are stored as a separate track and can be toggled on or off, but require player support. This tool creates hard subtitles.
What video formats are accepted?
The tool accepts MP4, WebM, MOV, AVI, and MKV files up to 500 MB. The output is always saved as MP4 for maximum compatibility across devices and platforms.
Why does it need to download ~25 MB the first time?
This tool uses FFmpeg compiled to WebAssembly to process video entirely on your device. The ~25 MB download is the FFmpeg engine. It happens only once and is then cached by your browser — subsequent uses are instant.
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