This call was removed in v362

This call is no longer available in the current runtime. Existed from v136 to v362. Shown here for historical reference.

faucet

Call Removed v136 → v362 (removed) #60

Claims free testnet TAO for development and testing.

Call Workflow

faucet

1. Validation

Signature, nonce, mortality, fees

Signature

Nonce

Mortality

Fee payment

2. Pre-dispatch

Permission & state checks

Permission checks

State validation

3. Dispatch

Execute logic, modify state

Faucet

4. Post-dispatch

Final result & fee settlement

ExtrinsicSuccess

Fees settled

Svelte Flow

Click items to navigate. Pan and zoom to explore.

Used by: developersminersvalidators

The Big Picture

Testnet TAO has no monetary value but lets you test everything. The faucet gives you free testnet TAO so you can experiment with registration, staking, validation, and all other operations without risk. It's your sandbox funding source. Use it liberally during development, but remember it only works on testnet - mainnet has no faucet.

Why This Matters

Testing on mainnet is expensive and risky. Testnet + faucet lets you make mistakes for free. Test your miner, debug your staking script, experiment with parameters - all without spending real TAO or affecting the real network.

Example Scenario

You're developing a miner for subnet 1. Connect to testnet, generate a test coldkey, then call faucet() (possibly with a POW solution if required). You receive 100 testnet TAO. Use it to burned_register, stake, and test your entire workflow before deploying to mainnet.

Common Questions

Does the faucet work on mainnet?: No. Faucet is testnet-only. On mainnet, you must acquire TAO through exchanges, transfers, or mining rewards. There's no free money on mainnet.
How much TAO does the faucet give?: Network-configurable, typically 100-1000 testnet TAO per request. Enough to test most operations. Request again after the cooldown if you need more.
Why does the faucet require POW on some testnets?: To prevent abuse. Without POW, bots could drain the faucet. The POW requirement ensures you put in minimal effort, keeping testnet TAO available for real developers.
Can I use testnet TAO on mainnet?: No. Testnet and mainnet are completely separate networks. Testnet TAO has zero value and cannot be transferred or converted to mainnet TAO.

Use Cases

Get free TAO on testnet for development
Fund test accounts for integration testing
Bootstrap testnet mining/validation operations
Test staking flows without real money

Input Parameters

#	Name	Type	Description
0	block_number	u64	block_number (u64) (RAO -> TAO (/ 10^9))
1	nonce	u64	nonce (u64)
2	work	Vec<u8> Vec	work (Vec<u8>)

Permissions

Origin

Unknown

Required Role

Coldkey

Requirements

Running on testnet (not mainnet)
Faucet is enabled on the network
Account cooldown period has passed
Valid POW solution provided (if required)

Effects

Events Emitted

Faucet

Postconditions

Coldkey balance increased by faucet amount
Cooldown timer reset for this account

Side Effects

TestnetFaucetUsed event emitted
Rate limited to prevent abuse

Code Examples

import { ApiPromise, WsProvider } from "@polkadot/api";
import { stringCamelCase } from "@polkadot/util";

const provider = new WsProvider("wss://entrypoint-finney.opentensor.ai:443");
const api = await ApiPromise.create({ provider });

// Build faucet call
const block_number = 0;
const nonce = 0;
const work = 0;

const call = api.tx[stringCamelCase("SubtensorModule")][stringCamelCase("faucet")](
  block_number,
  nonce,
  work
);

Runtime Info

View Source

Pallet Index: 7
Call Index: 60
First Version: v136
Removed In: v362

Back to SubtensorModule Calls