Burn SRT subtitles into MP4 — free, in your browser
WebCodecs H.264 encoder · WebGPU rendering · works in Chrome 113+, Edge 113+, Firefox 147+, Safari 17+
SRT (SubRip Subtitle) is the most common subtitle format on the web — plain text with timecodes. Burning an SRT into an MP4 means the captions become a permanent part of the video frames. Every player on every device shows them, even when subtitle support is turned off. BurnSub does this entirely in your browser using WebCodecs, so your video never uploads anywhere.
How to burn srt subtitles into mp4
- 1
Open BurnSub
Visit burnsub.com — no signup, no install, no app store.
- 2
Drop your MP4
Drag the MP4 onto the dropzone. Files up to 4K are supported with no size cap because everything stays on your device.
- 3
Import your SRT
Click "Import subtitles" and select your .srt file. BurnSub parses the timecodes and shows them on the timeline.
- 4
Pick a caption style
Choose one of 30+ named presets (TikTok, MrBeast-Yellow, Hormozi-Bold, cinema-letterbox, anime, etc.) or customize fonts, colors, and animations.
- 5
Burn and download
Click "Burn + Download". WebCodecs encodes the new MP4 with hardcoded subtitles locally on your GPU. Save the file — no upload happened.
Frequently asked
What is the difference between SRT and burned-in subtitles?
SRT is a separate text file with timecodes. The video player overlays it during playback. Burned-in subtitles are baked into the video frames themselves — they show up everywhere, including TikTok, Instagram, and any player that ignores SRT.
Do I need to install ffmpeg or HandBrake?
No. BurnSub uses the browser's native WebCodecs API to encode the new MP4. No installation, no command line, no plugin.
Will my video lose quality?
BurnSub encodes the output at the same resolution and bitrate as your input by default. Up to 4K is preserved without downscaling. You can choose lower output settings if you want a smaller file.
Is there a file size limit?
No. Since BurnSub runs entirely on your device, there is no server upload to cap. Limits depend on your device's memory.
Does the SRT file get uploaded anywhere?
No. Both your SRT file and the MP4 stay local to your browser. Nothing is sent to any server — verifiable in your browser's DevTools network tab.