The deal, in plain words.

Last updated August 19, 2026 · applies to the preview release

1. What you're agreeing to

These terms are an agreement between you and the team behind C4Stage (“we”, “us”). By creating an account or using the service you accept them. If you are using C4Stage on behalf of an organisation, you confirm you may bind that organisation to these terms.

2. The service, and its preview status

C4Stage is a collaborative architecture-diagramming service: modelled systems, an AI assistant, live health overlays, version history, sharing and related features. It is currently offered as a free preview: features may change, be added or be removed, capacity limits may be adjusted, and the service may be interrupted or paused without notice. We work to keep it stable and your data safe, but the preview comes with no uptime commitment or support guarantee.

3. Accounts

Accounts are created through an invitation or sign-up with a valid email address. Keep your credentials confidential — you are responsible for activity under your account. Tell us promptly if you believe your account has been compromised. You must be at least 16 to use the service.

4. Your content

The models, diagrams, comments, icons and configuration you put into C4Stage remain yours. You grant us the limited license needed to operate the service: hosting, storing, displaying, versioning and transmitting your content to the people you share it with, and processing it through the service's features (for example, sending a prompt and the relevant model context to our AI provider when you use the assistant). You are responsible for having the rights to what you upload and for not storing content you are not permitted to share — including secrets and credentials, which do not belong in a diagram.

5. Acceptable use

Don't misuse the service: no unlawful content or use, no attempts to breach or probe the service's own security, no accessing other users' data beyond what they shared with you, no overloading the service or circumventing its rate limits, and no pointing health probes at endpoints you are not authorised to monitor.

6. The AI assistant

Assistant replies are machine-generated and can be wrong, incomplete or out of date. Review changes before saving them, and don't treat assistant output as professional advice. Assistant requests are processed by a third-party AI provider on our behalf, as described in the privacy policy.

7. Sharing

Content you share is visible to the people you share it with, under the role you gave them. Public share links make a read-only canvas reachable by anyone who has the link — create and revoke them deliberately. You control your links; we are not responsible for where a link you distributed ends up.

8. Fees

Every account starts on a free trial; the plans page lists what each paid tier costs and includes. Paid plans are sold through Stripe, which acts as the merchant of record for the purchase: Stripe takes the payment, adds and remits any sales tax, VAT or GST your location requires, sends the receipt and invoice, and handles payment-level support and disputes. Your subscription renews each month or year until you cancel it; cancelling stops the next charge and the plan stays on until the end of the period you paid for. There are no refunds beyond what consumer law where you live provides, and nothing you built is ever held behind a paywall — a lapsed plan makes the account read-only, not empty. See the billing policy for the details.

9. Ending things

You can stop using the service and ask us to delete your account and content at any time. We may suspend or terminate accounts that break these terms, and we may wind down the preview itself — if we do, we will make reasonable efforts to give notice and a way to export your content (the model JSON and Mermaid export exist for exactly that).

10. Disclaimers & liability

The service is provided “as is” and “as available”, without warranties of any kind, express or implied — including fitness for a particular purpose and non-infringement. Diagrams and health overlays are aids, not a monitoring system of record; do not rely on them as your only alerting. To the maximum extent permitted by law, we are not liable for indirect, incidental, special or consequential damages, or loss of data, profits or business, arising from use of the preview; our total liability for any claim is limited to the amount you paid us for the service in the twelve months before the claim — during the free preview, that is zero.

11. Changes to these terms

We may update these terms as the product evolves — the date above always reflects the current version. Material changes will be flagged in the product. Using the service after a change means you accept the updated terms.

12. Contact

Questions about these terms? Reach the team through your workspace administrator or the channel that came with your invitation. By post: C4Stage, 100 King Street West, Suite 5700, Toronto, ON M5X 1C7, Canada.