Frequently Asked Questions

Yes — completely free, with no Pro tier. The site is funded by Google AdSense, not subscriptions. There's no watermark, no signup, no upload, no time limit. The full feature set is available to everyone, on the same URL.

No. BurnSub processes everything inside your browser tab using WebCodecs (decode + encode) and WebGPU (Whisper-Turbo for speech-to-text). Your video file never leaves your device.

Chrome 113+, Edge 113+, Firefox 147+, and Safari 17+. WebCodecs (required for encoding) needs one of these. Older browsers won't work.

MP4, MOV, WebM, and MKV with H.264 or H.265 (HEVC) video. Output is always H.264 MP4 for maximum compatibility (TikTok, YouTube, Instagram, X, Discord all accept it).

There isn't one. BurnSub doesn't upload anything, so there's no server cap. The practical limit is your device's RAM. Most laptops handle 4–6 GB files fine; phones cap around 1–2 GB.

BurnSub uses Whisper-Turbo (OpenAI's speech-to-text model). Accuracy is typically 92–97% on clear speech in supported languages. Background noise, heavy accents, or technical jargon may reduce accuracy. Captions are editable before burning.

Whisper-Turbo supports 99 languages. The most reliable: English, Spanish, French, German, Italian, Portuguese, Dutch, Russian, Polish, Turkish, Arabic, Hindi, Chinese, Japanese, Korean. Smaller languages may have lower accuracy.

Yes. After auto-caption finishes, every line is editable. You can fix wording, adjust timing, merge or split lines before burning into the video.

Roughly real-time on a recent laptop (a 5-minute video takes 4–8 minutes including auto-caption + burn). Older devices and 4K content take longer. M-series Macs and recent Intel/AMD laptops with hardware encode are fastest.

Yes — three ways: (1) "Share Style" generates a short permalink URL you can bookmark or share. (2) "Export Recipe" downloads a tiny JSON file you can re-import. (3) Your last 5 styles auto-save to browser local storage.

Other tools watermark to push you toward their Pro tier. BurnSub doesn't have a Pro tier — there's no business reason to watermark. Your output is exactly the file you'd get from a $24/month plan elsewhere, free.

Yes, on iPhone (iOS 17+) and Android (Chrome). Phones can handle 1080p clips up to a few GB. For long 4K projects, a laptop is faster.

Yes. The output video is yours — you can post it on YouTube, TikTok, Instagram, sell it, embed it, anything. There's no license restriction.

You can upload an existing .srt or .vtt file instead of auto-generating, then style and burn it in. Export as .srt is also planned for a future update.

Yes. No video content is uploaded, stored, or transmitted. Standard anonymized web analytics and Google AdSense are the only data flows. Read the full privacy policy.