Build installable Deno web apps that open immediately, keep working offline, and sync when users choose.
lofi generates an Astro + Preact app backed by durable local data. Users start with a private, on-device account—no sign-in or network required—and can add Jazz-powered sync and recovery later without replacing that identity or rewriting product code.
Documentation · API reference · Live demo · JSR package · MIT License
Building with an AI agent? Feed it llms.txt for an index of the documentation, or llms-full.txt for the complete docs and API reference in one file — both generated from the deployed version's sources.
Requires Deno 2.9+. It is the only global runtime you need.
deno run -A jsr:@nzip/lofi/create my-app
cd my-app
deno task devOpen the URL printed by the development server. The starter is a small task app: add a task and reload the page to see that it remains in durable local storage. Once the page is open, disconnect the network and you can keep reading and writing data locally. Prefer to look first? A reworked build of the starter runs at demo.lofi.host, deployed by the release workflow from the published package.
The generated app starts in local-only mode. You do not need an account, a backend, or an .env
file to begin building. To provision managed Jazz sync, scaffold with --sync or run
deno task jazz:provision later; either way users keep the account they already have.
Continue with Getting started when you are ready to replace the task example with your own schema, permissions, hook, and UI.
- Local-first data read from durable local storage; failures are surfaced, never silently swapped for memory.
- Identity from the first launch, with optional sync and account recovery via passkey or a 24-word phrase.
- Narrow collaboration templates — private, direct-share, and fixed-role group access behind a
small
@nzip/lofi/accessAPI. - Verbs with sync-boundary effects —
s.mutationdeclares named verbs whose writes return aWriteHandle;onSynced/onRejectedconsequences run on the originating device from a durable journal that survives reloads, with pending-write and per-row sync status hooks for the UI. - A schema compatibility gate — each build stamps the schema range it understands, so a stale offline shell that meets newer data pauses editing (reads continue), shows the update path, and coordinates the worker swap across tabs.
- Local-first test helpers — Playwright-backed two-client fixtures for offline writes and convergence.
- An explicit authoring boundary: product code owns schema, permissions, config, islands, styles, and tests; lofi owns storage, identity, sync, lifecycle, and PWA plumbing.
The documentation covers all of this in depth: guides, commands, project layout, installed-app recipes, examples, and the identity and recovery model.
lofi is designed for mobile web apps where offline operation is a requirement, not a best-effort enhancement. Keep these current constraints in mind:
- lofi is an early, pre-1.0 release; do not yet trust it with data you cannot afford to lose.
- The data layer is Jazz 2 alpha and deliberately pinned to a reviewed version (stack and version policy). Five known engine defects at the current pin are each documented in a decision record and covered by an automated canary that fails loudly when a version bump changes the behavior.
- The sync server reads unencrypted columns. The threat model states what the server can and cannot see, what the user holds, and which fields the schema can seal.
- The supported browser floors are Android Chrome 148+ and iOS Safari 16.4+.
- Recovery is user-controlled: lofi does not retain recoverable account material on the server, so the recovery phrase must be kept safe.
This repository is the framework's development monorepo. package/ contains the @nzip/lofi
source, apps/reference/ is the reference app against which the generator is validated, and
website/ builds the lofi.host documentation site.
See CONTRIBUTING.md for the repository workflow and the DevX contract for the framework's testable promises and boundaries.