Partage

Partage is a fully encrypted, local-first bill-splitting application for trusted groups (friends, family, roommates). It runs as an installable Progressive Web App and works offline.

Try Partage · How encryption works · Self-hosting guide

• Privacy-first. All sensitive data is end-to-end encrypted in the browser. The server only relays ciphertext.
• Local-first. Data is stored in IndexedDB and synced opportunistically when online.
• No accounts. Identity is a locally-generated ECDSA P-256 keypair. No email, no password.
• Immutable audit trail. Entries are versioned via an event log; modifications and deletions preserve history.
• Deterministic convergence. Concurrent edits across devices replay into identical state.

Features

• Expenses, transfers, and income with arbitrary payer/beneficiary splits
• Multi-currency entries with per-group default currency
• Stable settlement plan (anchored balances + post-anchor transfers)
• Member claiming, aliases, and merging
• Virtual members for people who haven't joined
• Activity feed and per-member audit log
• Entry search, filtering, sorting, CSV export, and Splitwise import
• Read-only mode for archived or imported groups, with a rejoin flow
• Push notifications and PWA install (Android, iOS, desktop)
• Internationalization (English and French for now)

See docs/SPECIFICATION.md for the canonical feature spec.

Architecture

Layer	Technology
Frontend	Elm 0.19.1, elm-ui, elm-concurrent-task
Crypto	Web Crypto API (AES-256-GCM, ECDSA P-256, SHA-256)
Local storage	IndexedDB
Backend	Minimal zero-knowledge Node.js relay (Hono over SQLite)
Build	elm-watch, esbuild, travelm-agency (i18n)

The relay backend lives in packages/relay. It stores only encrypted blobs and signed metadata — it cannot decrypt anything. Its Hono application keeps Fetch-style HTTP and injected-storage boundaries, while the Node.js/WebSocket transport and SQLite lifecycle stay outside; a future platform port can therefore implement the relay contract without retaining dormant adapters today.

Page.Group.EntriesTab and Page.Group.ActivityTab intentionally own separate entry renderers. Entries presents interactive current ledger state grouped by business date; Activity presents compact historical snapshots and diffs grouped by event time. Shared domain and presentation policies should remain narrower than those views.

Getting started

Requirements: Node.js ≥ 22.5 and pnpm ≥ 10.

pnpm install
pnpm -C packages/relay install
pnpm dev

The root application and relay deliberately have independent lockfiles. The relay lockfile is the self-contained production dependency boundary copied into its Docker image. Each package's pnpm-workspace.yaml records the dependency install scripts it permits; add exceptions deliberately rather than allowing scripts globally.

pnpm dev runs the relay, elm-watch, esbuild, the i18n watcher, and the service worker builder concurrently via run-pty. Open http://localhost:8090: the relay serves the built frontend and API from that one origin, while elm-watch provides hot compilation behind it. Development installs a network-only service worker so an earlier production cache cannot hide rebuilt files; the page may reload once when that worker takes control.

Relay settings a local run wants — the operator dashboard, push, the feedback form — go in packages/relay/.env, which the relay reads at startup, so pnpm dev needs no exported variables. That file is untracked, and exported variables still win over it. The settings themselves are the deployment's own, listed in docs/DEPLOY.md.

Build for production

pnpm build:optimize

Output is written to dist/.

Tests and linting

pnpm test          # elm-test
pnpm lint          # elm-review
pnpm format:check  # elm-format --validate

Deployment

See docs/DEPLOY.md for container deployment.

Repository layout

src/              Elm source (Domain, Page, Infra, ...)
vendor/           Vendored Elm packages
packages/relay/   Minimal relay backend (Apache-2.0)
public/           app shell, static-home assets, manifest, icons, JS glue
marketing/        static-site page modules and demo-video tooling
translations/     travelm-agency translation files
tests/            elm-test suites
review/           elm-review configuration
docs/             Specification and deployment docs

License

The Partage frontend is licensed under the Mozilla Public License 2.0 — see LICENSE.

The packages/relay subproject is licensed under Apache-2.0 — see packages/relay/LICENSE.

This project depends on third-party Elm and JavaScript libraries under BSD-3-Clause, MIT, and MPL-2.0 licenses; their copyright notices are preserved in their respective sources.