We built a Splitwise alternative where the link is the account

Описание и применение

Создана альтернатива Splitwise без регистрации: один URL‑ссылка служит как приглашение, аутентификация и ключ доступа. Приложение использует BigInt для точных расчётов, фиксирует FX‑курсы при вводе, работает офлайн и обновляется через SSE, при этом не раскрывает данные.

Задача

Users avoid creating accounts; need a single link that invites, authenticates, and stores data.

Результат

A zero‑account split‑tracking app that uses a single link as bearer credential, ensures precise money handling, locks FX rates, supports offline usage, and leaks no data via realtime updates.

Рабочий процесс

• Generate 16‑byte random key, base64url‑encode, append to readable stem to form URL
• Treat URL as bearer credential; no recovery or owner override
• Store money amounts as strings + BigInt; use deterministic remainder distribution
• Lock FX rates at entry; fetch rates via same‑origin route
• Queue new expenses offline; replay when online; limit features to avoid CRDT complexity
• Use SSE to notify clients of changes; clients refetch data; stream carries no room data
• Route push, FX, receipt model through allow‑listed proxy; no egress from containers

Доказательства

The link is a bearer credential. 16 random bytes, base64url, appended to a readable stem. No recovery, no owner override. Treat it like a key.

Источник

Money as strings + BigInt. A Number never touches an amount except for display. Equal splits hand out remainders deterministically.

Источник

FX locked at entry. Editing an expense never re‑prices history. Rates are fetched through a same‑origin route so the browser never talks to a second host.

Источник