Local Blockchain Development

Clarinet ships with a complete local blockchain environment so you can build, test, and debug smart contracts without deploying to a public network.

Starting your local blockchain

Launch devnet with all required services:

clarinet devnet start

Useful flags:

Option	Description
--manifest-path <path>	Use an alternate Clarinet.toml
--no-dashboard	Stream logs instead of showing the interactive UI
--deployment-plan-path <path>	Apply a specific deployment plan
--use-on-disk-deployment-plan	Use an existing plan without recomputing
--use-computed-deployment-plan	Recompute and overwrite the plan
--package <path>	Load a packaged devnet configuration

Prerequisites

Devnet requires Docker. If you see “clarinet was unable to create network,” ensure Docker Desktop is running or the Docker daemon is started.

By default the dashboard displays service health, recent transactions, block production, contract deployments, and resource usage. Use --no-dashboard in CI or when you prefer streaming logs.

Core services and features

Devnet starts these services for you:

Service	Port	Purpose
Stacks node	20443	Processes transactions and mines blocks
Bitcoin node	18443	Provides block anchoring in regtest mode
Stacks API	3999	REST API for blockchain data
Postgres	5432	Indexes blockchain data
Stacks Explorer	8000	Browse transactions in a web UI
Bitcoin Explorer	8001	View the Bitcoin regtest chain

Devnet includes pre-funded accounts:

::get_assets_maps
;; +-------------------------------------------+-----------------+
;; | Address                                   | STX Balance     |
;; |-------------------------------------------+-----------------|
;; | ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM | 100000000000000 |
;; | ST1SJ3DTE5DN7X54YDH5D64R3BCB6A2AG2ZQ8YPD5 | 100000000000000 |
;; | ST2CY5V39NHDPWSXMW9QDT3HC3GD6Q6XX4CFRK9AG | 100000000000000 |
;; | ST2JHG361ZXG51QTKY2NQCVBPPRRE2KZB1HR05NNC | 100000000000000 |
;; | ST2NEB84ASENDXKYGJPQW86YXQCEFEX2ZQPG87ND  | 100000000000000 |
;; +-------------------------------------------+-----------------+

When devnet starts it automatically deploys your project contracts so you can interact immediately.

$ clarinet devnet start
Deploying contracts...
Deploying counter.clar        ✓  ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.counter
Deploying token.clar         ✓  ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.token
Deploying marketplace.clar   ✓  ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.marketplace

All contracts deployed successfully

Configuration and customization

Devnet behavior is controlled by configuration files in your project.

Basic configuration

settings/Devnet.toml defines network settings:

[network]
name = "devnet"

# Service ports
stacks_node_rpc_port = 20443
stacks_api_port = 3999
stacks_explorer_port = 8000
bitcoin_node_rpc_port = 18443

[network.devnet]
bitcoin_controller_block_time = 30_000  # 30 seconds

disable_bitcoin_explorer = false
disable_stacks_explorer = false
disable_stacks_api = false

Port configuration

Avoid local conflicts by customizing ports:

stacks_node_rpc_port = 30443
stacks_api_port = 4999
postgres_port = 6432
stacks_explorer_port = 4020

Mining intervals

Control block production speed:

bitcoin_controller_block_time = 1_000     # Fast development (1 second)
bitcoin_controller_block_time = 30_000    # Standard testing (30 seconds)
bitcoin_controller_block_time = 120_000   # Realistic timing (2 minutes)

Custom accounts

Add accounts with specific balances:

[accounts.treasury]
mnemonic = "twice kind fence tip hidden tilt action fragile skin nothing glory cousin"
balance = 10_000_000_000_000

[accounts.alice]
mnemonic = "female adjust gallery certain visit token during great side clown fitness like"
balance = 5_000_000_000_000

Accessing services

Devnet exposes several ways to interact with the blockchain.

Stacks Explorer

Visit the explorer to browse transactions, blocks, contract state, and account balances:

http://localhost:8000

API endpoints

Query blockchain data with the Stacks API:

curl http://localhost:3999/v2/info

Common endpoints:

• /v2/info – network information

• /v2/accounts/{address} – account details

• /v2/contracts/source/{address}/{name} – contract source code

• /extended/v1/tx/{txid} – transaction details

Direct RPC

Submit transactions directly to the Stacks node:

curl -X POST http://localhost:20443/v2/transactions \
  -H "Content-Type: application/json" \
  -d @transaction.json

Useful RPC endpoints:

• /v2/transactions – broadcast transactions

• /v2/contracts/call-read – read-only contract calls

• /v2/fees/transfer – fee estimates for STX transfers

Advanced configuration

Performance optimization

For faster development cycles:

settings/Devnet.toml

[network.devnet]
bitcoin_controller_block_time = 1_000

disable_bitcoin_explorer = true
disable_stacks_explorer = true
disable_stacks_api = false

Epoch configuration

Test different Stacks versions:

[epochs]
epoch_2_0 = 0     # Stacks 2.0 from genesis
epoch_2_05 = 0    # Stacks 2.05 from genesis  
epoch_2_1 = 0     # Stacks 2.1 from genesis
epoch_2_2 = 0     # Pox-2 from genesis
epoch_2_3 = 0     # Pox-3 from genesis
epoch_2_4 = 0     # Pox-4 from genesis
epoch_3_0 = 101   # Nakamoto activation at block 101

Package deployment

Create reusable devnet configurations:

$ clarinet devnet package --name demo-env
Packaging devnet configuration...
Created demo-env.json

Use a packaged configuration:

$ clarinet devnet start --package demo-env.json

Common issues

Docker connection errors — “clarinet was unable to create network”

Follow these steps to fix Docker connection issues:

Ensure Docker Desktop is running (macOS/Windows).Start the Docker daemon (sudo systemctl start docker) on Linux.Confirm permissions with docker ps.Reset Docker to factory defaults if problems persist.

Verify Docker status:

docker --version
docker ps

Port already in use — “bind: address already in use”

Find and stop the conflicting process (macOS/Linux):

lsof -i :3999
kill -9 $(lsof -t -i:3999)

Windows equivalent:

netstat -ano | findstr :3999
taskkill /PID <PID> /F

Or update ports in settings/Devnet.toml:

stacks_api_port = 4999
stacks_explorer_port = 4020
postgres_port = 6432

High resource usage (slow performance, high CPU or memory)

Optimizations:

disable_bitcoin_explorer = true
disable_stacks_explorer = true
bitcoin_controller_block_time = 60_000

Set Docker resource limits:

docker update --memory="2g" --cpus="1" <container_id>

Clean up old data:

clarinet devnet stop
docker system prune -a
rm -rf tmp/devnet

Network already exists — “network with name `.devnet` already exists”

Remove the orphaned network:

docker network rm <project>.devnet

If you're unsure of the name:

docker network ls | grep devnet
docker network rm <network-name>

Prevent the issue by stopping devnet with Ctrl+C and pruning orphaned networks:

docker network prune

Docker stream error during startup — “Fatal: unable to create image: Docker stream error”

Error: "Fatal: unable to create image: Docker stream error"

This error often occurs when Docker images are corrupted or when explorers fail to start properly.

Solution 1 - Disable explorers:

If you don't need the web explorers, disable them in settings/Devnet.toml:

disable_bitcoin_explorer = true
disable_stacks_explorer = true

Solution 2 - Clean Docker environment:

Remove all containers and images, then restart:

Terminal

docker stop $(docker ps -a -q)
docker system prune -a
docker volume prune

Solution 3 - Full cleanup and restart:

Terminal

docker stop $(docker ps -a -q)
docker network rm <project-name>.devnet
docker system prune --all --volumes
clarinet devnet start

This ensures a clean Docker environment for devnet to start fresh.

Contract deployment failures

Ensure dependencies deploy first in Clarinet.toml:

[contracts.sip-010-trait]
path = "contracts/sip-010-trait.clar"

[contracts.token]
path = "contracts/token.clar"

Validate contracts before deployment:

clarinet check

Check logs:

clarinet devnet start --no-dashboard

Deploy manually if needed:

clarinet deployments generate --devnet
clarinet deployments apply --devnet

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