01
Burned in, not a sidecar file
The captions are rendered into the frames. You get one finished video, not an SRT file that TikTok, Reels, and Shorts have no way to accept anyway.
Auto captions for video
Captions on your iPhone video in about two minutes
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 and export. The captions are burned into the video file, so it posts to TikTok, Reels, or Shorts with the captions already visible.
Download on the App StoreSee how it works
Free to try: 5 transcriptions, clips up to 2 minutes, exports carry a small Capster badge.
The whole edit, on the phone it was shot on
Word-by-word highlight, one of 9 caption styles.
- 99 languages, detected for you
- 9 caption styles
- 0 videos uploaded
How it works
Four steps, no desktop editor
Four steps, no desktop editor, and no account to create.
- 1
Pick a clip
Import from Photos or Files. Capster only ever sees the clip you choose, and it stays on your phone.
- 2
Wait about a minute
The audio track is transcribed with word-level timings. 99 languages, detected automatically.
- 3
Pick a style, fix a word
9 presets. Tap any word to correct it. The preview you are editing is the render.
- 4
Export
Captions are burned into the frames and the finished file lands in your camera roll, ready to post.
What it looks like
Three screens from the app: the animation controls, the caption editor, and the style panel.
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.
Shot it. Captioned it.
Posted it.
Why Capster and not a desktop editor: the clip is already on the phone, and so is everything needed to finish it.
02
The preview is the export
The editor runs the same compositor as the final render, so the file you save is the thing you were looking at. No surprise re-layout after a five-minute export.
03
99 languages, detected for you
Speak in Spanish, Hindi, Portuguese, or Arabic and Capster works out the language itself. No picker to set wrong before a one-minute transcription.
04
9 styles that already fit
Word-by-word highlight, one-word-at-a-time, clean studio captions. Sized and placed for vertical video, so platform UI does not sit on top of your text.
It fits in the gap in your day
Captioning a short clip by hand is about twenty minutes of nudging text boxes. This is roughly two, on the phone the video is already on.
Privacy
No account,
no video upload
There is no sign-in. The video stays on your device; only the audio track is sent for transcription, and it is deleted afterwards.
Pricing
Exporting is free. Pro lifts the limits. Prices are the same ones the App Store charges, billed by Apple.
Free
$0
- 5 transcriptions
- Clips up to 2 minutes
- 2 caption styles
- Exports carry a Capster badge and outro
Pro, monthly
$6.99/month
- Unlimited transcriptions
- No clip length limit
- All 9 caption styles
- No badge, no outro
Pro, yearly
$29.99/year
3-day free trial · save 64%
- Everything in Pro
- Works out at $2.50 a month
- Cancel any time in App Store settings
Subscriptions renew automatically unless cancelled at least 24 hours before the period ends, and are managed in Settings → your name → Subscriptions. Full pricing, the free-versus-Pro table, and how the trial works, or read the Terms of Use.
The short answers
Questions people ask
How do I add captions to a video on my iPhone?
Open Capster, pick a clip from Photos, and wait about a minute while the audio is transcribed. Choose a caption style, edit any words the transcription got wrong, then export. The captions are burned into the video file, so it posts to TikTok, Reels, or Shorts with the captions already visible.
Is Capster free?
Yes, with limits. The free tier covers 5 transcriptions, clips up to 2 minutes, and 2 caption styles, and exported videos carry a small Capster badge. Exporting itself is never blocked. Pro removes all of that for $6.99 a month or $29.99 a year.
Does my video get uploaded anywhere?
The video itself is never uploaded. It stays in the app's private storage on your device. To generate captions Capster extracts the audio track and sends only that to its speech-to-text provider over HTTPS, which transcribes it and then deletes it. Nothing accompanies that upload — not the filename, and not an identifier of you, because Capster has no account.
What languages does Capster caption?
Capster transcribes 99 languages and detects the spoken language automatically, so there is no language picker to get wrong. Accuracy depends on audio quality, accent, and background noise, and captions are machine-generated, so read through them before you publish.
Are the captions burned in or a separate subtitle file?
Burned in. Capster renders the captions into the video frames and saves one finished file to your camera roll — there is no SRT sidecar to upload separately. That is what social platforms need, since none of them accept a subtitle file alongside a vertical video upload.
What do I need to run it?
An iPhone running iOS 16.0 or later, and a network connection for the transcription step. Everything else — editing, styling, preview, and the final render — happens on the device. 9 caption style presets ship with the app.
Something not working? Support has the fixes for transcription and restore problems.
The rest of it, in detail
Caption the clip you already shot
It is on your phone. So is Capster. Free to try, no account.