> ## Documentation Index > Fetch the complete documentation index at: https://mintlify.com/provablehq/leo/llms.txt > Use this file to discover all available pages before exploring further. # leo devnode > Run a single-node local development server with instant block creation The `leo devnode` command runs a single-node local development server with instant block creation, ideal for rapid testing and iteration. ## Syntax ```bash theme={null} leo devnode [OPTIONS] ``` ## Subcommands ### start Start the devnode server. ```bash theme={null} leo devnode start [OPTIONS] ``` ### advance Advance the ledger by a specified number of blocks. ```bash theme={null} leo devnode advance [OPTIONS] ``` ## Start Options Private key to use for the devnode. Defaults to test private key. Default test key: `APrivateKey1zkp8CZNn3yeCseEtxuVPbDCwSyhGW6yZKUYKfgXmcpoGPWH` is for development only. Network type: `mainnet`, `testnet`, or `canary`. Endpoint override (for configuration purposes). ## Advance Options Number of blocks to advance. Devnode endpoint URL. ## Examples ### Start Devnode ```bash theme={null} leo devnode start ``` Output: ``` 🚀 Starting Devnode... ✅ Devnode running at http://localhost:3030 Network: testnet Address: aleo1... Press Ctrl+C to stop. ``` The devnode: * Listens on `http://localhost:3030` * Creates blocks instantly on transaction receipt * Maintains in-memory ledger state * Provides REST API compatible with snarkOS ### Start with Custom Private Key ```bash theme={null} leo devnode start --private-key APrivateKey1zkp... ``` ### Advance Blocks In a separate terminal: ```bash theme={null} leo devnode advance --blocks 10 ``` Output: ``` ⏩ Advancing 10 blocks... ✅ Advanced to block 10 ``` This creates 10 empty blocks, useful for: * Testing time-dependent logic * Advancing past block height thresholds * Simulating network progression ### Advance Custom Number of Blocks ```bash theme={null} leo devnode advance --blocks 100 ``` ## Using the Devnode Once running, interact with it like any Aleo node: ### Deploy Programs ```bash theme={null} leo deploy \ --broadcast \ --devnet \ --endpoint http://localhost:3030 \ --private-key APrivateKey1zkp8CZNn3yeCseEtxuVPbDCwSyhGW6yZKUYKfgXmcpoGPWH ``` The devnode instantly creates a block with the deployment. ### Execute Transactions ```bash theme={null} leo execute main 1u32 2u32 \ --broadcast \ --devnet \ --endpoint http://localhost:3030 \ --private-key APrivateKey1zkp8CZNn3yeCseEtxuVPbDCwSyhGW6yZKUYKfgXmcpoGPWH ``` The devnode instantly creates a block with the execution. ### Query State ```bash theme={null} leo query block latest \ --endpoint http://localhost:3030 \ --network testnet ``` ## REST API The devnode provides a REST API compatible with snarkOS: ### Get Latest Block ```bash theme={null} curl http://localhost:3030/testnet/latest/block ``` ### Get Latest Height ```bash theme={null} curl http://localhost:3030/testnet/latest/height ``` Response: ``` 42 ``` ### Get Block by Height ```bash theme={null} curl http://localhost:3030/testnet/block/10 ``` ### Get State Root ```bash theme={null} curl http://localhost:3030/testnet/latest/stateRoot ``` ### Get Program ```bash theme={null} curl http://localhost:3030/testnet/program/hello_world.aleo ``` ### Broadcast Transaction ```bash theme={null} curl -X POST http://localhost:3030/testnet/transaction/broadcast \ -H "Content-Type: application/json" \ -d @transaction.json ``` ## Devnode vs Devnet | Feature | Devnode | Devnet | | ------------------ | --------------- | ----------------------------- | | **Nodes** | Single node | Multiple validators + clients | | **Block Creation** | Instant | Consensus (slower) | | **Consensus** | None | Full BFT | | **Startup Time** | Fast | Slower | | **Resource Usage** | Low | Higher | | **Realism** | Less realistic | More realistic | | **Use Case** | Rapid iteration | Integration testing | Use `leo devnode` for rapid development and iteration. Use [`leo devnet`](/cli/devnet) for more realistic testing. ## Block Creation Behavior The devnode creates blocks instantly when: 1. A transaction is broadcast 2. `leo devnode advance` is called ``` Transaction → Devnode → Instant Block ``` No waiting for consensus or block time. ## State Persistence The devnode maintains state **only in memory**: * State is lost when the devnode stops * No persistence to disk * Fast startup with clean state For persistent storage, use [`leo devnet`](/cli/devnet) instead. ## Default Configuration The devnode uses: ``` Endpoint: http://localhost:3030 Network: testnet Private Key: APrivateKey1zkp8CZNn3yeCseEtxuVPbDCwSyhGW6yZKUYKfgXmcpoGPWH Address: aleo1rhgdu77hgyqd3xjj8ucu3jj9r2krwz6mnzyd80gncr5fxcwlh5rsvzp9px ``` Never use the default devnode private key on mainnet or testnet. ## Development Workflow Typical workflow with devnode: ```bash theme={null} # Terminal 1: Start devnode leo devnode start # Terminal 2: Develop and test cd my_project leo build leo deploy --broadcast --devnet --endpoint http://localhost:3030 leo execute main 1u32 2u32 --broadcast --devnet --endpoint http://localhost:3030 # Make changes, rebuild, redeploy vim src/main.leo leo build leo deploy --broadcast --devnet --endpoint http://localhost:3030 # Advance time if needed leo devnode advance --blocks 100 ``` ## Environment Variables Configure devnode via `.env`: ```bash theme={null} PRIVATE_KEY=APrivateKey1zkp... NETWORK=testnet ENDPOINT=http://localhost:3030 DEVNET=true ``` Then simply: ```bash theme={null} leo devnode start leo deploy --broadcast leo execute main 1u32 2u32 --broadcast ``` ## Logging Devnode logs to stdout: ``` [2026-03-04 15:30:00] Starting Devnode on port 3030 [2026-03-04 15:30:00] Genesis block created [2026-03-04 15:30:01] REST API listening on http://localhost:3030 [2026-03-04 15:30:05] Received transaction at1abc... [2026-03-04 15:30:05] Created block 1 ``` For verbose logging: ```bash theme={null} RUST_LOG=debug leo devnode start ``` ## Stopping the Devnode Press `Ctrl+C` to stop: ```bash theme={null} ^C 🛑 Shutting down Devnode... ✅ Devnode stopped. ``` ## Troubleshooting ### Port Already in Use ``` Failed to bind to address: Address already in use ``` Solutions: 1. Stop existing devnode 2. Kill process using port 3030: ```bash theme={null} lsof -ti:3030 | xargs kill -9 ``` ### Transaction Not Confirmed If a transaction doesn't confirm: 1. Check devnode is running 2. Verify endpoint is `http://localhost:3030` 3. Check devnode logs for errors 4. Ensure transaction is valid ### State Mismatch If state is inconsistent: 1. Restart devnode (clears state) 2. Redeploy programs 3. Re-execute transactions ## Advanced Usage ### Custom REST Endpoints The devnode supports standard Aleo REST endpoints: ```bash theme={null} # Get account balance curl http://localhost:3030/testnet/program/credits.aleo/mapping/account/aleo1.../balance # Get transaction curl http://localhost:3030/testnet/transaction/at1... # Get program mappings curl http://localhost:3030/testnet/program/my_program.aleo/mappings ``` ### Programmatic Interaction Interact programmatically via HTTP: ```javascript theme={null} const fetch = require('node-fetch'); // Get latest height const height = await fetch('http://localhost:3030/testnet/latest/height') .then(r => r.text()); console.log('Current height:', height); // Advance blocks await fetch('http://localhost:3030/testnet/devnode/advance', { method: 'POST', body: JSON.stringify({ blocks: 10 }), headers: { 'Content-Type': 'application/json' } }); ``` ## Testing Strategies ### Unit Testing Use `leo test` for unit tests: ```bash theme={null} leo test ``` ### Integration Testing Use devnode for integration tests: ```bash theme={null} # Start devnode leo devnode start & DEVNODE_PID=$! # Run integration tests ./run-integration-tests.sh # Stop devnode kill $DEVNODE_PID ``` ### End-to-End Testing Use devnet for E2E tests: ```bash theme={null} leo devnet --num-validators 4 # Run E2E tests ``` ## Next Steps * [Deploy to devnode](/cli/deploy) * [Execute on devnode](/cli/execute) * [Use full devnet](/cli/devnet)