How to burn subtitles into a video (without uploading it)

Burned-in versus a separate subtitle file

There are two ways to put words on a video, and they are not interchangeable. A subtitle file — .srt or .vtt — sits next to the video and the player draws the text. The video itself is untouched, the viewer can usually turn the captions off, and you can fix a typo by editing a text file.

Burning in re-encodes the video with the text painted onto every frame. There is one file, the captions always show, and changing them means encoding again.

• Use a separate file for YouTube uploads, Vimeo, and anywhere a player will read it
• Burn in for Reels, TikTok, Shorts, and anywhere you are handing over one file
• Burn in when you cannot control the player — a slide deck, a website video, a WhatsApp send

Why most free tools stop before this step

Almost every free captioning tool will generate an .srt and then ask for money to burn it in. That is not arbitrary: for a server-based tool, burning in means re-encoding your video on their hardware, which costs real compute for every user. Transcription is comparatively cheap; re-encoding is the expensive half.

Doing it in the browser inverts that, because the encoder doing the work belongs to you. There is nothing to ration, which is why this tool does not paywall the step or stamp a watermark on the result.

Doing it here, step by step

Drop a video onto the tool. Nothing uploads — your browser reads the file directly off your disk.

Either press Transcribe to have the speech model write the captions, or import an .srt or .vtt you already have. Then edit them against the waveform: the tool flags any line that runs faster than a viewer can read, any cue too brief to register, and any place the model got stuck repeating itself.

Pick a caption style. The preview over the video is drawn by the same code that does the burn-in, so what you see is what gets encoded. Then press Burn captions into the video and download the MP4.

What quality to expect

Burning in always re-encodes, so there is a second generation of lossy compression. This tool spends a deliberately generous bitrate to make that invisible — there is no file size limit to respect and no bandwidth to pay for, so being stingy would buy nothing.

Output is H.264 in MP4, capped at 1080p. H.264 because it is the one codec every platform, phone and mail client plays; a smaller AV1 file that your recipient cannot open is a worse outcome than a larger one that works.