Hardcode subtitles into MP4 video — no upload, no watermark
No server upload · No watermark · Up to 4K · WebCodecs H.264 + WebGPU rendering
Hardcoding subtitles means the captions become pixels inside the video — they cannot be turned off, edited, or stripped out by a player. This is what TikTok, Reels, YouTube Shorts, and most social-media uploads need: subtitles that are visible immediately, on every device, without relying on player-side SRT support. BurnSub hardcodes locally using WebCodecs so you do not have to upload your source video to anyone.
How to hardcode subtitles into mp4 video
- 1
Drop your MP4 into BurnSub
Open burnsub.com and drop your video. Everything happens in your browser tab — no upload bar, no waiting room.
- 2
Auto-generate captions or import SRT
Either let Whisper-Turbo transcribe locally on your GPU, or paste/upload an existing SRT or VTT file.
- 3
Style the captions
Pick from 30+ named presets (TikTok-neon, MrBeast-yellow, Hormozi-bold, anime, cinema, podcast, gaming, kids-cartoon). All settings are previewed live.
- 4
Burn into the video
BurnSub renders captions frame by frame into your MP4 using WebCodecs. The output is a new MP4 with subtitles permanently embedded.
- 5
Download — file never left your device
Save the result locally. No upload happened at any step. Confirm in DevTools → Network tab if you are unsure.
Frequently asked
Why hardcode subtitles instead of using soft subtitles?
Hardcoded subtitles are guaranteed to show on every platform and device — TikTok, Instagram, Reels, Shorts, autoplay feeds, and any player that ignores SRT. Soft subtitles depend on player support and are often missing on social media.
Can hardcoded subtitles be removed later?
No. Once subtitles are burned into the video frames, they are part of the image. If you might need to re-edit them, keep the original SRT file as a backup.
Is this different from "burn-in" or "embed"?
No — "hardcode," "burn-in," and "permanent subtitle" all mean the same thing. The captions become pixels in the video instead of a separate text track.
Does the quality drop?
BurnSub re-encodes the video, which inherently re-compresses it once. Quality is preserved at your chosen bitrate and resolution. For lossless workflow keep your original — burning is always a one-way operation.
Do I need an account?
No. BurnSub has zero signup, zero login, zero account. Open the page, drop a file, download the result.
Ready to burn srt / vtt / auto-generated into mp4?
Free forever · No upload · No watermark · No signup
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