hidane (火種, the seed of fire) — a Firestore emulator without Java.

A single Rust binary that replaces the official Cloud Firestore emulator. No JVM. Starts in milliseconds. Tested for parity against the official emulator.

$ curl -fsSL https://hidane.dev/install.sh | sh v0.5.0 · macOS · Linux

Installs the latest release in ~/.local/bin, checked against its SHA-256. Homebrew, npm (Windows too), cargo and Docker: Install.

Read why Star on GitHub

v0.5.0 · hidane doctor, migrate, benchmark savings and report; Testcontainers

Why hidane

Java 21 is now required

firebase-tools 15 dropped support for Java older than 21. Running a local database should not require a JDK.

Source: firebase-tools v15.0.0 release notes

941 ms · 148 MiB

941 ms to start, 148 MiB idle

In our canonical benchmark environment, the official emulator takes a median 941 ms to open its port and sits at 148 MiB idle. hidane v0.4.0 on the same machine: 1.56 ms and 7.8 MiB.

Source: benchmark result, every sample included

11× slower

Writes slow down as data grows

With a listener attached, the official emulator's batch writes slow down in proportion to the number of documents: 11 times slower at 100k. hidane is designed so that a commit costs only what it changes: the same 100k documents take 4.9 s, flat per batch.

Source: measurements and raw logs

Startup and memory: medians for both emulators on one AWS c7i.xlarge (Ubuntu 24.04, Java 21, firebase-tools 15.33.0), 2026-10-13; methodology in bench/. Writes with a listener: Phase 0 measurements, not side by side, as the benchmark does not cover that case yet. Context: why hidane.

Works with

Status in v0.5.0: planned not verified verified

gRPCfirebase-admin (Node)verified

gRPC@google-cloud/firestoreverified

gRPCfirebase-js-sdk on Nodeverified

RESTfirebase-js-sdk Liteverified

WebChannelBrowser firebase-js-sdkverified

gRPCGoverified

gRPCPythonverified

gRPCJavaverified

gRPCiOSnot verified

gRPCAndroidnot verified

gRPCFlutter (mobile / desktop)not verified

WebChannelFlutter Webverified

filesfirebase-tools export / importverified

rulesSecurity Rulesverified

Verified means the client's results were compared with the official emulator's; not verified means hidane serves its transport but nobody has run that client yet. Which transport each SDK needs: compatibility.

Parity

hidane treats the official emulator as the oracle: its answers are recorded, and the test suite replays every recording against hidane. No claim of compatibility without a test behind it.

So far: 20,368 answers of the official emulator in 41 recordings, each replayed against hidane in CI, and SDK transcripts from both emulators compared side by side (results). How they are counted: docs/parity.md.

Area	Transports	Recorded answers	Compared in full	SDK transcripts
Documents & writesgRPC, REST	gRPC, REST	5,246	4,874	4 documented differences
Queries & aggregationsgRPC, REST	gRPC, REST	496	454	6 identical
TransactionsgRPC, REST	gRPC, REST	192	187	2 identical3 documented differences
Listen & Write streamsgRPC	gRPC	49	48	4 identical2 documented differences
RESTREST	REST	118	114	1 identical
WebChannelREST, WebChannel	REST, WebChannel	34	31	2 identical1 documented difference
Security RulesgRPC, REST, WebSocket, in-process	gRPC, REST, WebSocket, in-process	13,264	5,541	2 documented differences
Export & importREST, CLI	REST, CLI	70	67	3 identical
Auth & admin endpointsgRPC, REST	gRPC, REST	621	573	1 identical2 documented differences
Values & limitsgRPC, REST, WebChannel, in-process	gRPC, REST, WebChannel, in-process	278	274	—
Total		20,368	12,163	19 identical14 documented differences

Compared in full: answers whose test compares everything the recording keeps (status, message or body, values), masking only what changes from run to run, such as times and IDs. The others are compared on the Security Rules decision and its reasons, in part, or on their status; docs/parity.md breaks them down, test by test. SDK transcripts: the same steps run through an SDK against both emulators; a documented difference is one results/README.md or the parity exceptions explain. Known, intentional differences (68) are listed in parity exceptions.

Roadmap

v0.1

Server SDKs and native clients: firebase-admin, the Google Cloud libraries, iOS, Android and Flutter, running under firebase-tools.
v0.1 milestone on GitHub
v0.2

Security Rules, evaluated once per request as the official emulator decides them: reads, writes, listeners and queries, measured against it case by case, with its compiler warnings, rule coverage reports and debug() output. Released in v0.2.0; v0.2.1 feeds the Emulator UI's request monitor, and @firebase/rules-unit-testing is verified end to end, in Node and in the browser.
v0.2 milestone on GitHub
v0.3

Browser clients: firebase-js-sdk in the browser and Flutter Web. Released in v0.3.0: the SDK's own browser test suite passes on hidane as on the official emulator, 1,183 tests in Chromium, and Flutter Web is verified.
v0.3 milestone on GitHub
v0.4

Functions triggers: Firestore events delivered to the Functions emulator, v1 and v2, under firebase emulators:start. Released in v0.4.0: the events are recorded from the official emulator and replayed, and functions receive the same data end to end.
v0.4 milestone on GitHub

Scope, targets and risks: ROADMAP.

Install

Every channel installs the same release binaries: macOS (arm64, x86_64), Linux (arm64, x86_64; static) and Windows (x64).

GitHub ReleasesArchives, checksums, build provenanceavailable

cargo binstallcargo binstall hidaneavailable

Homebrew tapbrew install hidane-dev/tap/hidaneavailable

npmnpm install --save-dev hidaneavailable

pub.devdart pub global activate hidaneavailable

Dockerdocker run -p 8080:8080 ghcr.io/hidane-dev/hidaneavailable

curl | shcurl -fsSL https://hidane.dev/install.sh | shavailable