Terms of Service

You may not use the service, or any AI feature, to:

• create or process anything unlawful, or anything that infringes someone else’s rights;
• produce sexual content, content sexualising minors, graphic violence, hate speech, or harassment;
• impersonate a real person or organisation, or produce material meant to deceive or defraud;
• process secrets or confidential material you are not allowed to share with a third-party AI provider;
• abuse payments or free credits — for example a stolen card, a chargeback for credits you used, or several accounts to collect free credits;
• overload, scrape, or attempt to break into the service, or automate it beyond normal use.

The tool is provided without warranties and may change, break, or be discontinued.

Generated PNG, JPG, WebP, SVG, and PDF files are based on the diagram content you provide and Mermaid rendering behavior. You are responsible for ensuring you have the right to use, publish, or distribute your exported diagrams.

Some features are optional paid upgrades. A Pro subscription unlocks premium export styles and AI features, and one-time credit packs add AI usage credits. Current prices are shown on the pricing page and at checkout (a monthly Pro plan and a one-time credit pack). Payments are taken by PayPal, or — for card, Apple Pay and Google Pay where that checkout is offered — by Waffo (Waffo.com Limited), which sells those orders to you as merchant of record. Card checkout may add sales tax or VAT for your country, shown before you pay.

A Pro subscription renews automatically each billing period until you cancel. By subscribing, you authorize the payment provider you subscribed through to charge the recurring amount until cancellation. AI credits from a one-time pack are added to your balance once payment is confirmed.

You can cancel your subscription at any time from your account, with the payment provider directly, or by emailing us at hello@mermaidonline.org. After you cancel, your Pro access continues until the end of the period you have already paid for, and you will not be charged again.

If an AI feature fails, or a result is unusable because of a fault on our side, write to us and we will refund the credits or the payment. A refunded payment removes the credits it added. Credits already spent on results you kept, and Pro time already used, are not refundable, because the AI processing has been paid for on your behalf. We do not refund part of a billing period. Nothing here limits any statutory rights you may have.

These terms apply for as long as you use the service.

• What counts as a breach.Anything listed under “Acceptable use” above, and any use the law forbids.
• What we may do.Depending on how serious it is: refuse the request and remove the content, warn you, suspend AI features or the account for a time, or close the account permanently. Serious breaches — anything involving minors, fraud or payment abuse — lead to closure without a warning.
• If your account is closed for a breach. Your access to the account ends, unused AI credits are forfeited, any Pro subscription is cancelled so it is not charged again and its remaining paid time ends, and nothing already paid is refunded. Content the law requires us to report is reported to the authorities.
• If we close your account for any other reason, or stop offering the service, we refund the unused part of any Pro period you paid for and any credits you bought and did not use.
• You can leave at any time. Cancel Pro from your account, and email hello@mermaidonline.org to have your account and its records deleted. Deleting an account ends access to any credits left on it. The free editor and exports keep working without an account.
• If you think we got it wrong, email the same address from your account’s email; a person reviews every appeal and replies.

The AI generate, fix, edit, and architecture map tools are provided on a best-effort basis. AI output may be inaccurate, incomplete, or fail to render, and is not a substitute for your own review. AI requests you trigger are sent to our AI provider to produce a response, as described in our Privacy Policy.

Mermaid.js, Mermaid Chart, and related marks belong to their respective owners. This tool is not affiliated with Mermaid.js, Mermaid Chart, or their maintainers.

The service is provided “as is” without warranties of any kind. To the extent permitted by law, we are not liable for indirect or consequential damages arising from your use of the service.