What is b402 in a single sentence?
What is b402 in a single sentence?
b402 is a multichain payment protocol that gives AI agents and web services gasless, confidential, multi-token transactions across EVM-compatible chains.
How is b402 related to x402?
How is b402 related to x402?
Why not use traditional payment rails or API keys?
Why not use traditional payment rails or API keys?
Traditional systems rely on centralized processors, accounts, and manual flows.
b402 removes those barriers — enabling machine-to-machine, HTTP-native payments that settle instantly on-chain with minimal fees.
Is b402 only for crypto-native projects?
Is b402 only for crypto-native projects?
No. Any service — from API providers to AI agents to websites — can integrate b402 to enable programmatic, per-request or usage-based payments.
Which languages and frameworks are supported?
Which languages and frameworks are supported?
The b402 reference implementations are written in TypeScript, but the protocol is open and language-agnostic.
Anyone can implement it in Go, Rust, or any environment that supports HTTP requests and ECDSA/EIP-712 signing.
Developers are encouraged to open PRs or RFCs in the GitHub repository to expand SDK coverage.
Who operates the Facilitator?
Who operates the Facilitator?
The Facilitator is managed by the b402 core team. It is currently live on BNB Chain and Base.
Which networks and tokens are supported today?
Which networks and tokens are supported today?
| Network | Tokens | Status |
|---|---|---|
| BNB Chain | USDT, USDC, USD1 | Mainnet |
| Base | USDC, USDT | Mainnet |
Why does b402 work with multiple tokens, while x402 only supports USDC?
Why does b402 work with multiple tokens, while x402 only supports USDC?
x402 relies on EIP-3009 (
transferWithAuthorization), which is built into USDC but not implemented by most tokens (USDT, USD1, etc.). b402 introduces its own Relayer contract that accepts EIP-712 signed messages and executes standard transfer() calls on behalf of the user. This means any whitelisted ERC-20 token works, on any deployed chain.Does b402 support fiat on- or off-ramps?
Does b402 support fiat on- or off-ramps?
Not natively.
However, facilitators or third-party gateways can integrate fiat payment bridges for deposits or withdrawals if required.
Do I need to expose my private key to the backend?
Do I need to expose my private key to the backend?
No.
Agents or buyers sign locally in their runtime environment (browser, VM, or enclave).
Servers and facilitators only verify signatures — they never have access to private keys.
What is the relationship between b402 privacy and RAILGUN?
What is the relationship between b402 privacy and RAILGUN?
b402’s privacy pool uses a custom implementation inspired by RAILGUN’s zero-knowledge proof system. RAILGUN pioneered compliant on-chain privacy using zkSNARKs, encrypted commitments, and Merkle trees — b402 builds on these foundational cryptographic primitives.How b402 differs from Tornado Cash:
- Tornado Cash used fixed-denomination pools and offered no compliance mechanism. It was sanctioned by OFAC in 2022.
- b402’s privacy pool supports arbitrary amounts, integrates with ERC-4337 smart wallets for gasless operation, and is designed with compliance in mind — shielded balances can be verified against screening requirements without revealing transaction details.