> ## Documentation Index
> Fetch the complete documentation index at: https://docs.chainstack.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Base B20 token standard

> B20 is Base's native, ERC-20-compatible token standard, implemented as a precompile with built-in roles, transfer policies, and supply controls. Learn how it works and how to use it on Chainstack.

B20 is Base's native token standard, introduced with the [Beryl upgrade](https://docs.base.org/base-chain/specs/upgrades/beryl/overview) (Base mainnet activation June 25, 2026). It is an ERC-20 superset implemented as a native precompile rather than a smart contract: it keeps full ERC-20 compatibility while building roles, transfer policies, supply caps, pausing, memos, and `permit` directly into the chain.

You create a B20 token by calling the singleton B20 factory precompile — there is no token contract to write, deploy, or audit.

## B20 vs. ERC-20

|                     | ERC-20                              | B20                                                                               |
| ------------------- | ----------------------------------- | --------------------------------------------------------------------------------- |
| Implementation      | Smart contract you write and deploy | Native precompile                                                                 |
| Creation            | Deploy your own bytecode            | One `createB20` call to the factory                                               |
| Compliance features | Build them yourself                 | Roles, transfer policies, freeze-and-seize, pause, supply cap, and memos built in |
| Compatibility       | —                                   | Full ERC-20 selector parity — a drop-in for wallets, explorers, and indexers      |
| Cost and throughput | Standard EVM execution              | Cheaper and higher-throughput (native)                                            |

Because B20 implements the full ERC-20 surface, existing wallets, explorers, and indexers treat a B20 token like any other ERC-20.

## How B20 works

All B20 tokens are created through the singleton B20 factory precompile. A single call configures and creates the token in one transaction:

```solidity theme={"system"}
createB20(variant, salt, params, initCalls)
```

* `variant` — `ASSET` or `STABLECOIN`.
* `salt` — caller-chosen entropy that fixes the token's deterministic address.
* `params` — ABI-encoded name, symbol, initial admin, and decimals.
* `initCalls` — an optional batch of configuration calls (grant roles, set the supply cap, bind policies) applied atomically at creation.

### Precompile addresses

| Precompile          | Address                                      |
| ------------------- | -------------------------------------------- |
| B20 factory         | `0xB20f000000000000000000000000000000000000` |
| Policy registry     | `0x8453000000000000000000000000000000000002` |
| Activation registry | `0x8453000000000000000000000000000000000001` |

Token addresses are deterministic and encode the variant in the address itself: `[10-byte B20 prefix][1-byte variant][9-byte hash of deployer and salt]`. Tokens created by the factory start with `0xB200…`; the factory itself is `0xB20f…`. You can predict a token's address before creating it with `getB20Address(variant, deployer, salt)`.

## Variants

| Variant        | Decimals              | Adds                                                                        |
| -------------- | --------------------- | --------------------------------------------------------------------------- |
| **Asset**      | 6–18, set at creation | Rebase multiplier, on-chain announcements, batched issuance, extra metadata |
| **Stablecoin** | 6, fixed              | Immutable ISO-style currency code (for example, `USD`)                      |

## Built-in features

B20 ships a compliance and operations toolkit that an ERC-20 leaves you to build:

* **Role-based access control** — `DEFAULT_ADMIN_ROLE`, `MINT_ROLE`, `BURN_ROLE`, `BURN_BLOCKED_ROLE`, `PAUSE_ROLE`, `UNPAUSE_ROLE`, and `METADATA_ROLE`. The Asset variant adds `OPERATOR_ROLE`. A token can be made permanently admin-less.
* **Transfer policies** — each token binds allowlist or blocklist policies from the policy registry to per-actor scopes (transfer sender, transfer receiver, mint receiver).
  <Warning>Every policy scope defaults to `ALWAYS_ALLOW` at creation. An unconfigured B20 is fully open — constrain it intentionally in `initCalls`.</Warning>
* **Freeze-and-seize** — `burnBlocked` burns from a policy-blocked account, the path regulated issuers need.
* **Supply cap** — an optional cap enforced on every mint.
* **Granular pause** — pause `TRANSFER`, `MINT`, or `BURN` independently, with separate pause and unpause roles.
* **Memos** — attach a `bytes32` reference (a payment ID or settlement tag) to transfers, mints, and burns. Each is emitted as a `Memo` event for off-chain reconciliation.
* **ERC-2612 `permit`** and **ERC-7572 `contractURI`** are built in.

## Availability

B20 ships with the Beryl upgrade:

| Network      | Beryl activation         |
| ------------ | ------------------------ |
| Base Sepolia | June 18, 2026            |
| Base mainnet | June 25, 2026, 18:00 UTC |

Chainstack Base nodes serve the B20 precompiles, so you can create and query B20 tokens through your Chainstack Base endpoint.

## Use B20 on Chainstack

<Steps>
  <Step title="Deploy a Base node">
    [Deploy a Base node](/docs/manage-your-networks) on Chainstack and copy your endpoint.
  </Step>

  <Step title="Create a token">
    Call the B20 factory from a script or directly with `cast`. See the [Deploy a B20 token](/docs/base-tutorial-deploy-a-b20-token) tutorial for the full walkthrough.
  </Step>
</Steps>

## See also

* [Base: deploy a B20 token](/docs/base-tutorial-deploy-a-b20-token) — Chainstack tutorial
* [B20 token standard specification](https://docs.base.org/base-chain/specs/upgrades/beryl/b20) — Base
* [base-std](https://github.com/base/base-std) — Solidity interfaces and helpers for B20