When you can't follow,
just put your phone down.

Simul turns what you hear into bilingual captions in real time: the original on top, the translation below. Recognition and translation run entirely on this device — it works in Airplane Mode.

Frequently asked

I opened it and nothing appears

Language models have to be downloaded first. The app walks you through it on first launch; if you skipped that, go to Settings → Add a language. This step needs a network connection; after that, you never need one again.

How big are the models? How long does it take?

It depends on the language and your connection. The system does not report a total size in advance, so we do not invent a number to show you. Models are managed by iOS and shared across apps, so they do not count toward Simul's install size.

My language isn't listed

Which languages can be recognised is decided by your version of iOS, and it differs between releases. Updating to the latest system version usually adds a few.

Only 5 languages at a time?

Yes — that is an iOS limit, not ours. Beyond that the system releases the least recently used one. Install it again whenever you need it.

Can it caption audio playing on my phone?

On iOS an app cannot capture another app's audio, and phone call audio is never available — both are system-level restrictions. For now: play the video out loud and let Simul listen through the microphone.

Why is the last line dimmed?

That line means "this sentence isn't finished; the text may still change." Once the sentence settles it turns white. So you always know which lines you can trust.

Can the Apple Watch app work on its own?

No. watchOS itself provides no speech recognition or translation, so the watch app only displays captions pushed from your iPhone and lets you start and stop remotely. Your iPhone must be nearby and running.

Does it record me? Is anything stored?

Neither. Audio is processed live and discarded; captions live only in memory and are gone when you leave the screen. See the Privacy Policy.

Support and feedback

For problems, language requests, or anything else, email dengzhaofun@gmail.com.

When reporting a caption problem, this helps a lot: open Settings, tap the Version row 7 times, turn on "Show diagnostics," then send us a screenshot of the line at the bottom of the caption screen.