Watch YouTube videos with two subtitle lines: the original, and your language.
Email: huyloind03w@gmail.com
We usually reply within 2 business days. Writing in English or Vietnamese is fine.
If you are reporting a problem with a specific video, please include the YouTube link — it saves a round trip. The app can do this for you: ⚙️ → Report an issue prefills the link and your settings.
Yes, the first time. DuoSub reads the video's transcript on your own device, because YouTube does not hand transcripts to servers. Once someone has added a video, everyone else gets it in about a second — including you, on your next device.
Two possible reasons. Either the video genuinely has no captions — DuoSub cannot invent the original dialogue, so those videos cannot be added — or YouTube is temporarily refusing the request from your device. If the video does have captions on YouTube, wait a few minutes and try again.
The free plan includes 3 AI-translated videos per day. The counter resets daily. DuoSub Pro removes the limit entirely. Videos you already translated stay on your device and do not count again — you can rewatch them as often as you like.
Open the subscription screen and tap Restore purchases. Note that Pro is tied to the DuoSub account you were signed in with when you bought it. If you signed in with a different Google or Apple account, sign back into the original one.
Subscriptions are billed and managed by Apple, not by us: iPhone Settings → your name → Subscriptions → DuoSub. Cancelling stops the next renewal; Pro stays active until the end of the period you already paid for.
Refunds are handled entirely by Apple at reportaproblem.apple.com. We cannot issue them on Apple's behalf.
In the app: Settings → Delete account. This permanently removes your account, your translation allowance and your subscription record. It cannot be undone, and it does not cancel an active subscription — cancel that separately in iPhone Settings.
Subtitles are translated by AI, sentence by sentence. It occasionally misreads a line that depends on context from much earlier in the video. Tell us the video and the timestamp and we will look at it.
iPhone or iPad running iOS 17 or later, and an internet connection. Videos must have captions on YouTube.