Twinsub terms of use

Last updated: 2026-10-29. Publisher: Poetical Engine LLC (hello@poeticalengine.com).

By installing or using Twinsub you agree to these terms.

What is free

• Dual subtitles are free and unlimited. They are translated on your own computer by Chrome's built-in translator; no subtitle text is sent to us.
• "Didn't catch that?" explanations are free up to a daily limit (currently 5 a day per install). We may change the free limit.

Twinsub Pro

Twinsub Pro is a paid subscription for more explanations: currently US$4.99 a month for up to 1,000 explanations a month. Prices and limits are shown before you pay, and taxes may be added where they apply.

• Payment is handled by our payment provider, which acts as the seller of record; we never see your full card number.
• The subscription renews each month until you cancel. You can cancel at any time and keep Pro until the end of the period you paid for.
• Unused explanations do not carry over to the next month.
• If Pro doesn't work for you because of a fault on our side, write to us and we will make it right, including a refund. Other refunds follow the law where you live.

What explanations send. Dual subtitles never leave your computer, but explanations, free or Pro, are written on our server. When you tap Explain, the words you marked, a few subtitle lines around them, the video's title, channel and id, and your answer language are sent to our server at api.poeticalengine.com, which passes the text to Anthropic's Claude API to write the answer. Nothing is sent until you tap Explain. Paying for Pro does not change this, and we do not keep a history of what you watch or ask. Details are in the privacy policy.

AI answers

Explanations are written by an AI model and can be wrong or incomplete. Use them to understand what you watch, not as professional, legal, medical or financial advice.

Fair use

Don't use Twinsub to overload our server, get around the limits, resell explanations, or send text that isn't from the video you are watching. We may suspend explanations for an install that does.

The software

Twinsub is provided as is. We work to keep it working as YouTube changes, but we can't promise it always will. Subtitles and videos belong to their owners; Twinsub only displays the subtitles your YouTube player already has, for your own viewing.

To the extent the law allows, our total liability to you is limited to what you paid us in the 12 months before the claim.

Twinsub is not affiliated with or endorsed by YouTube or Google.

Changes

We may update these terms. If a change affects Pro subscribers, we will say so before your next renewal, and you can cancel.

Questions: hello@poeticalengine.com