CaptionStack

Subtitle your videos in many languages — transcribed and translated entirely on your iPhone.

Need help?

Email support@uzum.services and we'll get back to you.

Common questions

The translations are empty

Automatic translation uses Apple Intelligence's on-device model, which needs an iPhone 15 Pro or later with Apple Intelligence switched on. Go to Settings ▸ Apple Intelligence & Siri, turn it on, and wait for the model to finish downloading — it can take a while the first time.

If your iPhone doesn't support Apple Intelligence, everything else still works: CaptionStack transcribes what you said, and you can type the other languages yourself in the editor.

The first transcription is slow

The first time you use a given language, iOS downloads Apple's speech model for it. That's a one-time system download, the same as adding a keyboard language. After it finishes, transcription runs offline and is much faster.

Which languages are supported?

Speak and transcribe (10): German, English, Spanish, French, Italian, Portuguese, Japanese, Korean, Chinese and Cantonese.

Translate into (15): all of the above except Cantonese, plus Dutch, Danish, Norwegian, Swedish, Turkish and Vietnamese.

Portuguese is available in Brazilian and European, Spanish in Spain and Latin American, and Chinese in Simplified and Traditional.

Where are my projects stored?

On your iPhone, and nowhere else. Projects stay until you delete them — swipe a project in the list, long-press it, or use Edit. Deleting the app removes every project along with it, so export anything you want to keep first.

Does the exported video have a watermark?

No. Exports are full quality with no watermark, ever.

Is there a subscription?

No. CaptionStack is a single purchase — no subscription, no in-app purchases, no ads, and no account.

Refunds

Purchases are handled entirely by Apple. Request a refund at reportaproblem.apple.com.

Privacy

CaptionStack collects nothing. Your videos, captions and translations never leave your device. Read the full privacy policy.

Requirements