Isar
maintenanceby Simon Choi and the Isar community · since 2021 · also known as Isar Database, isar_community
Fast Flutter/Dart object database with rich indexed queries, now stalled upstream.
maintenance. No stable release since 3.1.0 (April 2023) and the 4.0 rewrite never shipped; the community fork isar_community carries ongoing fixes.
Overview
Isar is a cross-platform embedded database for Flutter, written in Rust with a Dart API. Collections are annotated Dart classes, and you get composite and multi-entry indexes, full-text word indexes, links between objects, ACID transactions and a type-safe generated query builder. It became the most popular Flutter-native database after Hive. Upstream development has stalled: the last stable release is 3.1.0 from April 2023, and the announced 4.0 rewrite never shipped. Most active users now depend on the community fork isar_community or have moved to ObjectBox, Drift or Hive CE.
Strengths & trade-offs
Strengths
- +Type-safe, code-generated queries with composite and multi-entry indexes
- +Fast native core in Rust with async APIs that keep the UI thread free
- +Watchers make it easy to build reactive Flutter widgets
- +Built-in inspector for browsing data during development
Trade-offs
- −Upstream is effectively stalled; long-term maintenance depends on a community fork
- −No built-in sync
- −Web support was limited in 3.x
Great for
- +Existing Flutter apps already built on Isar
- +Local caches and offline data for Flutter mobile apps
Think twice for
- −New long-lived projects that need an active upstream
- −Apps needing sync out of the box
- −Non-Dart stacks
Capabilities
Native or official first-party support · 4 of 25 tracked
Scale & consistency
- Comfortable data size
- Small · ≤ 100 GB
- Horizontal scaling
- None
- Multi-region
- No
- Transactions
- Full ACID
- Consistency
- Strong
- Schema
- Strict
- Architecture
- Embedded
- Query languages
- Isar generated query builder (Dart)
Deployment
Ecosystem
Alternatives to Isar
Fast on-device object database with built-in HNSW vector search and an optional commercial sync server.
isar vs objectbox →Lightweight pure-Dart key-value store for Flutter; development continues in the Hive CE fork.
isar vs hive-dart →Object-oriented mobile database whose MongoDB sync service is gone; the local engine survives as open source.
isar vs realm →The in-process SQL engine that ships in every phone, browser and OS: one file, zero servers.
isar vs sqlite →Sync engine that keeps on-device SQLite in sync with Postgres, MongoDB, MySQL or SQL Server.
isar vs powersync →JavaScript database for browsers and Node that speaks the CouchDB replication protocol.
isar vs pouchdb →Isar FAQ
What is Isar?
Isar is an object database by Simon Choi and the Isar community, first released in 2021. Isar is a cross-platform embedded database for Flutter, written in Rust with a Dart API. Collections are annotated Dart classes, and you get composite and multi-entry indexes, full-text word indexes, links between objects, ACID transactions and a type-safe generated query builder. It became the most popular Flutter-native database after Hive. Upstream development has stalled: the last stable release is 3.1.0 from April 2023, and the announced 4.0 rewrite never shipped. Most active users now depend on the community fork isar_community or have moved to ObjectBox, Drift or Hive CE.
Is Isar open source?
Yes. Isar is open source. License: Apache License 2.0.
Does Isar support ACID transactions?
Yes. Isar supports full ACID transactions, with strong consistency.
Does Isar scale horizontally?
Isar does not scale horizontally; it runs on a single node, so you scale it up rather than out. It is comfortable at small scale (≤ 100 GB).
How can I run Isar?
You can self-host it and embed it in your application.
What is Isar best for?
Isar is a strong fit for existing Flutter apps already built on Isar; and local caches and offline data for Flutter mobile apps. Think twice for new long-lived projects that need an active upstream.
What are the best alternatives to Isar?
Common alternatives to Isar include ObjectBox, Hive (Dart), Realm (Atlas Device SDK), SQLite and PowerSync. The right choice depends on your workload, scale and hosting; WhichDB's smart match ranks them against your requirements.
Is Isar still maintained?
Isar is in maintenance mode. No stable release since 3.1.0 (April 2023) and the 4.0 rewrite never shipped; the community fork isar_community carries ongoing fixes.
How popular is Isar?
Isar ranks #426 of 844 databases on the WhichDB Score (3.8/100), and #10 among object databases. The score combines public adoption signals such as package downloads, GitHub activity, job posts and developer discussion.