CaptionOSHow to add captions to a video on your phone (Android or iPhone)
Open captionos.in in your phone’s browser (Chrome on Android, Safari on iPhone), sign in and tap New project to pick a video from your gallery. CaptionOS writes the captions word by word. Choose a style, fix any word, then export and save the MP4 to your phone. There is no app to install.
Step by step
- Open captionos.in in Chrome (Android) or Safari (iPhone).
- Create a free account or sign in.
- Tap New project (the + button) and choose a video from your gallery.
- Choose the language: Hinglish, हिन्दी, اردو or English. The captions appear with every word timed.
- Pick a style and fix any word in the transcript.
- Tap Export, render the MP4 and download it.
Saving the video to your phone
- Android: the MP4 goes to your Downloads, and shows up in your gallery or Files app.
- iPhone: Safari saves it to the Files app (Downloads). Open it there, tap Share and choose Save Video to put it in Photos.
Tips for editing on a phone
- Use Wi-Fi for long videos: the video uploads to your project so it can be exported.
- Keep the browser open until the upload finishes.
- On a 9:16 video, turn on Safe Area in the preview to see where captions stay clear of Instagram and YouTube buttons.
- Projects are saved to your account, so you can carry on later on a computer. The Free plan allows 1 active device at a time, so signing in somewhere new signs out the old device.
Questions
Do I need to install an app?
No. CaptionOS runs in the browser on Android and iPhone.
Does it work offline?
No. Transcription, saving and exporting happen on CaptionOS servers, so you need an internet connection.
Can I start on my phone and finish on a computer?
Yes. Sign in with the same account and open the project from your dashboard.