Flow Emulator: Local Flow Development Network

Understand the project

Practical overview

Use it when building or testing Flow applications against a local network, especially when you need to repeat tests against controlled state.

Run Flow transactions, scripts and tests locally without deploying to a live network.
Create repeatable local test states and roll back to a selected block height.
Connect a Flow project workflow with Flow CLI and FCL.

Before you choose

The project is open source under the Apache-2.0 license.

Flow CLI startup requires a flow.json file; the README points to flow init for creating one.
The emulator can also be used as a module in a Go project.
Flow CLI configuration uses flags, while Docker configuration uses environment variables.
The API is described by the project as having near feature parity with mainnet and testnet.

Check current requirements in the official documentation. Source-based guidance does not mean OpenViST has run or independently tested this project.

Source-based practical guide

Install the emulator module and initialize a blockchain instance in Go code.

A Go project.
A Flow service private key suitable for decoding; the example leaves the private-key string empty, so supply an appropriate value for your use.

Install the module with the command below.
Documented command
```
go get github.com/onflow/flow-emulator
```
In Go code, decode the private key with crypto.DecodePrivateKeyHex(crypto.ECDSA_P256, ...).
Create emulator options with emulator.WithServicePublicKey(privKey.PublicKey(), crypto.ECDSA_P256, crypto.SHA3_256).
Initialize the blockchain with emulator.NewBlockchain(opts...); the example then accesses it with blockchain.GetAccount(address).

The Go project has an initialized emulator blockchain instance that can be used through its blockchain methods.

The example does not provide a usable private-key value or full imports and error handling.
The source demonstrates an account lookup but does not provide a complete transaction or testing workflow.

Evidence and transparency

Source record details

Source availability: Active
Sources checked: 9 October 2026
Original website title: onflow/flow-emulator · Official homepage title · retained in its source language