How to
To add captions to a video on iPhone, open Capster, pick the clip from Photos, and wait about a minute while the audio is transcribed. Choose a caption style, fix any words the transcription got wrong, and export. The captions are burned into the video file, so it posts to TikTok, Reels, or Shorts with the captions already visible.
iPhone, iOS 16.0 or later. No account. Free to try. Updated September 2026
Open Capster and tap to import from Photos or Files. The video is copied into the app's own storage and stays on the device — nothing about it is uploaded.
Tap Generate captions. Capster sends the audio track — not the video — for speech-to-text, and it comes back word by word with timings. 99 languages, detected automatically, usually inside a minute for a short clip.
Choose one of the 9 presets, then change the font, size, colour, outline or position if you want to. The preview runs the same renderer as the export, so what you are looking at is the file you will get.
Tap any caption to correct a word, split a line that runs long, or retime a segment. Names, slang and product names are the ones worth checking; everything else is usually right.
Tap Export. The captions are rendered into the frames and the finished video saves to your camera roll at full quality, ready to post to TikTok, Reels or Shorts as it is.
The animation controls, the caption editor, and the style panel — the three places you spend the two minutes.
Animate captions in and out, or pop them word by word.
Tap any caption to fix a word, split a line, or retime it.
Font, size, colour, outline, letter case, word highlight.
You can. Photos, iMovie and the platform apps all let you place a text box on a clip. The cost is time and the result is worse.
A 45-second clip is roughly 120 words. Typed by hand that is transcribing while scrubbing, then nudging each text box onto the right frame. Two minutes of automatic transcription and one style tap replaces the whole job.
Automatic transcription returns a timestamp per word, which is what makes karaoke highlight and one-word-at-a-time captions possible. A hand-placed text box only knows when you dragged it.
Text added inside TikTok or Instagram lives in that post. Download your own video back and the words are gone. Burned-in subtitles travel with the file.
Not to the video file. iOS shows automatic captions inside apps that supply them, and Photos will read text on screen, but nothing built into iOS writes captions into a video you export. To post a captioned clip you need an app that renders the text into the frames.
About two minutes end to end. Transcription of a one-minute clip usually lands inside a minute, picking a style is a tap, and the export runs in seconds. The slow part is reading through the words and fixing names, which is worth doing before you post.
No. Exporting is never blocked. Without Pro you get 5 transcriptions and clips up to 2 minutes, and the exported file carries a small Capster badge and a short end card. Pro removes all three.
The video is never uploaded. Capster extracts the audio track and sends only that to its speech-to-text provider over HTTPS, which transcribes it and deletes it. There is no account, so nothing identifying you travels with it either.
Yes, and you should. Tap any caption to rewrite the words, split a line, or change when it appears and disappears. Restyling applies to the whole video at once, so you can change the look without touching the text again.
Something not behaving? Support has the fixes for transcription and restore problems.
It is on your phone. So is Capster. Import it, wait a minute, export it captioned.
Free to try: 5 transcriptions, clips up to 2 minutes, exports carry a small Capster badge. iPhone, iOS 16.0+. No account.