b402

Gasless crypto payments on BSC.

Install

pip install b402

Usage

export PRIVATE_KEY="0x..."

from b402 import pay

result = pay(amount="0.01", token="USD1", recipient="0x...")

if result.success:
    print(f"TX: {result.tx_hash}")
else:
    print(f"Error: {result.error}")

First payment auto-approves $10,000 worth (one-time, costs gas). Future payments use existing allowance.

Defaults to BSC mainnet.

Manual Control

from b402 import B402

b402 = B402()

# Check approval
approved, allowance = b402.check_approval("USD1")

# Setup
if not approved:
    b402.setup("USD1")

# Pay
result = b402.pay(amount="0.01", token="USD1", recipient="0x...")

How It Works

First Payment:

1. Checks token allowance
2. Approves up to $10,000 if needed (costs gas once)
3. Sends payment (gasless)

Subsequent Payments:

1. Uses existing allowance
2. Sends immediately (gasless)
3. Re-approves automatically when low

Security

Capped approvals prevent unlimited token exposure.

Most SDKs:

approve(relayer, 2^256-1)  # Infinite

B402:

approve(relayer, 10_000 * 10^18)  # $10k cap

API

pay()

from b402 import pay

result = pay(
    amount="0.01",
    token="USD1",
    recipient="0x...",
    network="mainnet",  # Optional
    auto_approve=True,  # Optional
    debug=False         # Optional
)

B402()

from b402 import B402

b402 = B402()  # mainnet

Methods:

• b402.setup(token) - One-time approval
• b402.check_approval(token) - Check approval status
• b402.pay(amount, token, recipient) - Send payment

Supported Tokens

Mainnet: USD1, USDT, USDC Testnet: USDT

Network Details

BSC Mainnet (Chain ID: 56)

• Relayer: 0xE1C2830d5DDd6B49E9c46EbE03a98Cb44CD8eA5a
• USD1: 0x8d0d000ee44948fc98c9b98a4fa4921476f08b0d
• USDT: 0x55d398326f99059fF775485246999027B3197955
• USDC: 0x8AC76a51cc950d9822D68b83fE1Ad97B32Cd580d

BSC Testnet (Chain ID: 97)

• Relayer: 0x62150F2c3A29fDA8bCf22c0F22Eb17270FCBb78A
• USDT: 0x337610d27c682E347C9cD60BD4b3b107C9d34dDd

License

MIT