How the OnePage App Is Built

OnePage doesn't have a public API, this page isn't developer documentation. It's a plain-language explanation of how the app is built, for parents, attorneys, or anyone who wants more detail than a typical FAQ before trusting it with a custody record. For the legal specifics, see our Privacy Policy.

The data model

Every record in OnePage, messages, expenses, calendar changes, carries a createdBy, createdAt, and a content hash. Confirmed messages and expenses are append-only: they're never hard-deleted or edited in place. Editing a message or expense creates a new version rather than overwriting the old one, so both parents can trust the record wasn't quietly changed later. This is the same design pattern used for audit logs in financial and legal software, applied to the day-to-day facts of a custody arrangement.

"Tamper-evident" describes this integrity property specifically, it means changes are detectable, not that data is somehow unchangeable at the infrastructure level. It is a separate property from encryption, which protects data in transit and at rest. Both are covered in more detail in the Security section of our Privacy Policy.

Where your data lives

The app runs on Firebase (Google Cloud): Firestore for structured data (schedules, messages, expenses, family records) and Cloud Storage for photos, videos, and uploaded documents. Cloud Functions handle server-side logic that shouldn't run on a client device, invite acceptance, account deletion, and push notification delivery.

AI features

OnePage's AI features, the tone check, Ask OnePage, weekly summaries, and document extraction, run through Amazon Bedrock, calling an Anthropic Claude model hosted on AWS infrastructure in the us-east-1 (N. Virginia) region. Bedrock model invocation logging is turned off on our account, so AWS is not configured to retain a persistent log of request or response content for these calls. The full detail, including what this does and doesn't guarantee, is in Section 6 of our Privacy Policy.

Security

Data is encrypted in transit (TLS) and at rest. Access to a family's data is scoped by Firestore security rules to that family's members, enforced server-side, not just hidden in the app's UI.

Free vs. Plus

The custody calendar and messaging are free for both parents, always, and never gated behind a subscription. Plus adds PDF export, the AI tone check, expense splitting, and support for more than one child. A single Plus subscription on either side unlocks these for the whole shared family. See Pricing for current plans.

Platform availability

OnePage is a native app for iOS and Android. There is currently no web app and no public API for third-party integrations.

Questions we haven't covered here? Check the Help Center for how-to guidance, or contact us directly.