How to Add Captions to a Video in Your Browser
Add word-perfect, styled captions to any video in minutes, right in your browser. No upload, no install, and your footage never leaves your device.
Most video is watched on mute. People scroll feeds in public, in bed, at work, with the sound off by default. If your clip relies on audio to land, it gets skipped. Captions are what keep a muted viewer watching, and adding them no longer means a desktop editor or a slow upload to someone else's server.
This is the short version of how to caption any video, right in your browser, in the time it takes to make a coffee.
What you need
Two things. A video clip, and a browser. That is the whole list.
You do not need to install software, create a project file, or learn a timeline editor first. The clip can be vertical for TikTok, Reels, and Shorts, or wide for YouTube. Your original size is preserved either way.
The five-minute version
Here is the flow from raw clip to captioned MP4:
- Open the caption generator and drop in your clip.
- It transcribes the speech automatically, with a timestamp on every word.
- Read through and fix any word the model misheard.
- Pick a style: font, color, outline, and how the active word is highlighted.
- Export a burned-in MP4, or download a clean subtitle file.
That is it. The slowest part is usually deciding which look you like, and you can start from a preset to skip even that.
Edit before you publish
Automatic transcription is accurate, but no model is perfect. It can trip on a brand name, a bit of slang, or a moment where two people talk over each other.
The fix should take seconds, not minutes. In the studio every caption sits on a timeline over the audio waveform, so you can see exactly where each line falls. Click a word to correct it, drag a caption to retime it, or split and merge captions until the pacing feels right. You stay in control of the final text.
Keep your footage private
Here is the part most tools gloss over. When you upload a video to a web app, a copy of your footage lands on a server you do not control. For a quick clip that might be fine. For client work, unreleased footage, or anything personal, it is a real concern.
ReelCaption works differently. Your video is processed in your browser and never leaves your device. Only the extracted audio, which is tiny, is sent off to be transcribed, and it is not kept afterward. The pixels stay with you.
Burned-in captions or a subtitle file?
You have two ways to ship captions, and they solve different problems:
| Output | Best for |
|---|---|
| Burned-in MP4 | Short-form clips where captions must always show |
| .srt or .vtt file | Long-form YouTube, where viewers toggle subtitles |
Burned-in captions are part of the video, so they appear whether or not the viewer has subtitles turned on. A subtitle file stays separate and toggleable, which suits longer videos and accessibility. If you are unsure, the full breakdown is in SRT vs burned-in captions.
Make them readable
Captions only work if they can be read at a glance on a small, muted, fast moving screen. Keep each line short, sync the highlight to the spoken word, and give every letter enough contrast to survive your busiest shot. The complete set of rules lives in how to style captions people actually read.
One clip, every platform
Each feed places its own buttons and labels over your video, so caption placement that works on YouTube can get covered on TikTok. The platform guides cover the safe zones and dimensions for TikTok, Instagram Reels, YouTube Shorts, and YouTube, so your text never lands under an interface element.
Start now
Captioning a video used to be a chore reserved for the final edit. It is now a two-minute step you can do for every clip you post. Drop a video into the free caption generator, style it the way you want, and export a captioned MP4 before your coffee is cold.