Isar

What Isar is

Isar is an open-source NoSQL database for Flutter apps that need local data access, including when a network connection is unavailable. It runs on Android, iOS, and the web, and setup is designed to avoid configuration and boilerplate. A database can hold hundreds of thousands of records, with efficient asynchronous queries. Developers can use composite and multi-entry indexes, query modifiers, JSON support, and built-in full-text search. Queries are statically typed and checked at compile time, while transactions are handled automatically; if an error occurs, changes are rolled back. Parallel query operations and multi-isolate support are also available. Isar is Apache licensed and free forever at no cost. Its footprint is about 1–1.5 MB added to an app download, while Isar Web adds only a few KB. Platform-specific constraints include a 16 MB object limit and a prefix-query string limit on VM platforms. On the web, synchronous methods, certain filters, and NaN are unsupported.

Who it suits

Isar suits Flutter developers building apps that need local data access when a network connection is unavailable. It is particularly relevant when the app needs typed queries, full-text search, or concurrent query work across Android, iOS, and web.

Limits

On VM platforms, objects can be at most 16 MB, and prefix where-clauses can use only the first 1024 bytes of a string. On web, synchronous methods, splitWords() and matches() filters, and NaN are unsupported.

Getting started

1. Open https://isar.dev/.
2. Use Isar with a Flutter project targeting Android, iOS, or web.
3. Start with its minimal setup, which requires no configuration or boilerplate.

Verdict

Choose Isar if you are building a Flutter app that needs offline local storage, typed queries, and automatic transactions without a configuration-heavy setup. Check the VM and web constraints against your query and object requirements before choosing it.