Advanced English sentences, written by you.

Otonna is a guided training platform that helps English learners build accurate, varied complex sentences through progressive rewriting.

You start with a simple English sentence. Each level develops one skill: precise vocabulary, structural variation, idea development, abstraction, and natural integration.

No. Otonna does not give you templates to memorize. Every Library pattern is extracted from a sentence you built yourself through the five-level method. It records a reusable structure you have already produced, so you can apply the same skill to new ideas without relying on saved material.

No. Source sentences and rewrites must always be in English. The interface and feedback are available in English, Simplified Chinese, Traditional Chinese, Korean, Japanese, Spanish, Brazilian Portuguese, and Vietnamese.

When you return to Practice, Otonna reopens your unfinished sentence with the same number of attempts left, so reopening it costs nothing. If you choose to start a different sentence, the unfinished one is closed, its original credit is not returned, and the new sentence uses another credit.

One credit is used when a new sentence is ready and you can begin practicing it. If Otonna cannot generate or save the sentence, the credit is returned automatically. Rewriting the same sentence and receiving feedback do not use more credits; you can submit up to 10 versions for that sentence.

Daily subscription credits refill at 00:00 UTC, not at midnight in your local timezone. The local time therefore depends on where you live. Any unused daily credits disappear at the refill and do not carry over.

Yes. Each pack expires 12 months after the date you bought that pack, whether or not you have started using it. If you own several packs, Otonna uses credits from the pack that will expire first.

At present, Otonna does not add Canada’s GST/HST sales taxes because its current Canadian sales do not yet require tax registration. The total shown on the Checkout screen is the amount you pay. If Otonna later has to collect tax, Checkout will show the tax before you confirm payment.

You can request a full refund for a credit pack within 14 days of buying it only if none of its credits has started a paid sentence. Starting the sentence counts as use; you do not have to finish all five levels. The same rule applies to a subscription payment: request within 14 days and do not start a paid sentence during that billing period. An approved subscription refund ends access immediately. After use, canceling only stops the next renewal.

Contact support if a charge is duplicated or incorrect. While a refund or card dispute is being reviewed, Otonna may temporarily pause the related subscription access or purchased credits so they are not used twice. Access is restored if the refund does not proceed or the dispute is decided in your favor. Approved refunds go back to the original payment method; the bank decides when they appear.

Your normal account and practice data are deleted or stripped of information that identifies you. Otonna may keep only the payment facts needed for tax, accounting, refunds, fraud prevention, or payment disputes. This can include an order ID, amount, date, and refund status. These retained records do not include your full card number or the sentences you wrote.