Launch a B20 token on Base by calling the B20 Factory precompile.
B20 is an ERC-20 superset that runs as a native precompile on Base, which makes transfers cheaper and higher-throughput than a standard contract token while keeping full ERC-20 compatibility. Roles, supply caps, pausing, policy gating, memos, and permit are built into the chain.A standard ERC-20 leaves that logic for you to build, audit, and maintain. With B20, you call the singleton B20 Factory to create a token, fully configured, in a single transaction.This guide creates an Asset token, mints its initial supply, and verifies the balance onchain. To accept the token as payment in an app, continue with Accept B20 payments.
Standard forge cannot simulate calls to B20 precompile addresses (they hold no contract bytecode) and aborts with call to non-contract address. Base’s base-forge registers the precompiles into its EVM. It installs alongside your existing Foundry toolchain without overwriting it — use base-forge, base-cast, and base-anvil for all commands in this guide.
base-forge init b20-quickstart && cd b20-quickstartbase-forge install base/base-std --no-git
Add the remappings and the base = true flag to foundry.toml (under [profile.default]). base = true tells Base’s forge build to run the B20 precompiles inside its EVM, so the deploy script’s local simulation can call the factory:
foundry.toml
base = trueremappings = [ "base-std/=lib/base-std/src/", "base-std-test/=lib/base-std/test/",]
The interfaces compile with any Solidity >=0.8.20 <0.9.0.
The factory’s single entry point is createB20(variant, salt, params, initCalls):
variant: ASSET or STABLECOIN. This guide uses ASSET.
salt: caller-chosen entropy that fixes the deterministic token address.
params: ABI-encoded name, symbol, initial admin, and decimals.
initCalls: optional batch of config calls applied at creation.
1
Write the create script
Use B20FactoryLib to encode params and initCalls. Create script/CreateToken.s.sol:
script/CreateToken.s.sol
// SPDX-License-Identifier: MITpragma solidity ^0.8.20;import {Script, console} from "forge-std/Script.sol";import {B20Constants} from "base-std/lib/B20Constants.sol";import {B20FactoryLib} from "base-std/lib/B20FactoryLib.sol";import {IB20Factory} from "base-std/interfaces/IB20Factory.sol";import {StdPrecompiles} from "base-std/StdPrecompiles.sol";contract CreateToken is Script { function run() external returns (address token) { // For the quickstart, one account is admin + minter. address account = vm.envAddress("ACCOUNT_ADDRESS"); bytes32 salt = keccak256("my-first-b20"); // Name, symbol, initial DEFAULT_ADMIN_ROLE holder, decimals (6-18). bytes memory params = B20FactoryLib.encodeAssetCreateParams("My Token", "MYT", account, 18); // Configuration applied atomically at creation. bytes[] memory initCalls = new bytes[](2); initCalls[0] = B20FactoryLib.encodeGrantRole(B20Constants.MINT_ROLE, account); initCalls[1] = B20FactoryLib.encodeUpdateSupplyCap(1_000_000e18); vm.startBroadcast(); token = StdPrecompiles.B20_FACTORY.createB20(IB20Factory.B20Variant.ASSET, salt, params, initCalls); vm.stopBroadcast(); console.log("B20 token created at:", token); }}
Encode with B20FactoryLib. The native implementation rejects non-canonical calldata with AbiDecodeFailed; the helpers produce canonical encoding.
Asset decimals are fixed at creation and must be in [6, 18]. The supply cap is optional; the no-cap sentinel is type(uint128).max (the cap can never exceed uint128.max).
Want a stablecoin instead?
Use the STABLECOIN variant and its params encoder. A stablecoin fixes decimals at 6 and carries an immutable ISO currency code (uppercase A–Z) instead of a configurable decimals value:
On success the script logs the new token’s address. The factory’s address starts 0xB20f.... The tokens it creates start 0xB200...:
If you see TokenAlreadyExists, the salt keccak256("my-first-b20") is already registered on this network or anvil instance. Either restart base-anvil for a fresh state, or change the salt in the script to a unique value.
Output
== Logs == B20 token created at: 0xB200...
3
Capture the token address
Save the address to an environment variable so the next step needs no copy-paste. The broadcast artifact holds the return value:
Appending to .env keeps TOKEN_ADDRESS available in later steps, even in a new terminal session.
The broadcast path includes the chain ID, which the CHAIN_ID value in your .env supplies: 84532 for Sepolia, 84538453 for Vibenet, 31337 for local base-anvil.
