hidane

A Firestore emulator without Java, in one Rust binary

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Hiroki Nomura[maker]· 8h ago
Hey everyone 👋 I'm the maker. We built hidane: A Firestore emulator without Java, in one Rust binary. I'd love your honest feedback, and I'm here all week to answer questions!

hidane (火種, "the seed of fire") replaces the official Cloud Firestore emulator with a single Rust binary. No JDK: firebase-tools 15 made Java 21 a requirement, and hidane needs none.

Same wire protocols: gRPC, REST and WebChannel on one port, so the Admin SDK, the Google Cloud libraries and the web SDK (Node, Lite and the browser) connect unchanged.
Runs under firebase-tools: hidane exec -- firebase emulators:start.
Tested against the official emulator: its answers are recorded (28 fixtures) and hidane's test suite replays every recording; REST matches byte for byte. Its bugs are not reproduced, and every difference is documented.
Fast: 5.5 ms to open its port and 7.4 MiB idle, against 0.74 s and 95 MiB; writes stay flat with listeners attached (measured on different machines; a same-machine run is planned).
Exports in the official format, both ways.

Install with curl -fsSL https://hidane.dev/install.sh | sh, Homebrew, npm, cargo or Docker. Open source, MIT OR Apache-2.0.

Note: v0.1 does not enforce Security Rules (every request is allowed). Rules are on main and ship in v0.2; until then, keep the official emulator for rules tests.

Unofficial; not affiliated with Google. Firebase and Cloud Firestore are trademarks of Google LLC.

Open Source DB Testing

hidane is a Rust-based Firestore emulator that runs without Java.

for: Developers needing a local Firestore emulator without a JDK.
pricing: open source
license: Apache-2.0

hidane-dev/hidane 3 0Rustupdated 8 hours ago

v0.1.0hidane 0.1.02 days ago

works withfirebase-admin (Node)

Key features

6 features of hidane

Single binary, no JVM — Runs as one Rust executable, eliminating the need for a Java runtime.
Millisecond startup — Starts in ~5.5 ms and uses only 7.4 MiB of memory.
Full protocol support — Implements gRPC, REST and WebChannel on a single port for all SDKs.
Export/Import compatibility — Exports and imports data in the official emulator format.
Parity testing — Validated against 28 recorded fixtures to match official emulator responses.
Multiple install methods — Available via curl script, Homebrew, npm, cargo, Docker and binary releases.

Use cases

Fast local development of Firestore-backed apps without installing Java
CI pipelines that need quick Firestore emulation
Testing Firestore security rules once v0.2 is released
Running firebase-tools emulators:start with hidane as a drop-in replacement
Benchmarking write performance at large document counts

hidane vs alternatives

all alternatives →

	hidane	Firebase	Supabase	Appwrite	Convex
Best for	Java-free Firestore emulation	Google-provided Firestore emulation	Postgres-based backend platform	Open-source full-stack backend	Reactive TypeScript backend
Pricing	Open source	Subscription	Subscription	Subscription	Subscription
DevHunt upvotes	1	0	0	0	0
Launched	Oct 2026	—	—	—	—

hidane vs Firebase: Official Firebase emulator requires Java 21, hidane is Java-free and faster to start
hidane vs Supabase: Supabase provides a full Postgres backend, not a Firestore-compatible emulator
hidane vs Appwrite: Appwrite offers a complete backend suite, whereas hidane only emulates Firestore without Java
hidane vs Convex: Convex is a reactive backend database, not a drop-in Firestore emulator