Privacy Policy

This page explains how Futari collects, uses, and protects your personal data.

Data we collect

• Basic account information from Google OAuth: name, avatar, and email address.
• Expense data you enter manually, including transactions, settlements, split preferences, and shared asset records.
• Invite links and acceptance times (used to link the two accounts).
• Usage behavior and error information (used to improve the Service — see Third-party services below).

How we use your data

• To display the shared ledger interface between you and your partner and calculate balances.
• To power features such as recurring rules and monthly reviews.
• To detect and fix errors in the Service (via Sentry error tracking).
• To analyze feature usage and improve the product experience (via PostHog, with no personally identifiable information).

Where data is stored

Data is stored on Supabase servers in the Tokyo, Japan region, protected by encrypted connections and access controls. Sensitive fields within your 愛物 records — including a child's full name, national ID number, health insurance card number, a car's licence plate, and a home address — are encrypted with AES-256-GCM before being written to the database. The database never holds plaintext; decryption only occurs through the application itself.

Data retention

Your account data is retained for as long as your account remains active. Deleted transactions are kept as soft-deleted records for up to one year before being permanently removed by an automated process. Following account deletion, all related data will be removed from our servers within 14 business days.

Third-party services

• Google (OAuth sign-in)
• Apple (OAuth sign-in)
• Supabase (backend, database, realtime sync)
• Vercel (web hosting)
• Sentry (error tracking — collects anonymous error traces, no personally identifiable information)
• PostHog (product analytics — collects anonymous usage events, no personally identifiable information)
• Google Analytics 4 (traffic source analytics — IP-anonymised, cross-site personalisation disabled)

Your rights

You may sign out or delete your account at any time from the settings page. To export or enquire about your personal data, open an issue on GitHub。

If this policy changes, we will update this page and revise the date above. For any questions, open an issue on GitHub。