billmyagent (Python)

x402 payment SDK for Python. Pay x402-gated APIs as a server/agent and gate your own endpoints with a paywall. The Python counterpart of @billmyagent/payments-core, built on the official x402 library + eth-account.

Unlike the browser-oriented JS SDK, the agent here holds its private key directly — which is why this SDK matters for autonomous Python agents (LangChain, CrewAI, FastAPI services).

Install

pip install billmyagent              # buyer client
pip install 'billmyagent[fastapi]'   # + FastAPI seller middleware
pip install 'billmyagent[flask]'     # + Flask seller middleware

Pay an x402-gated API (buyer / agent)

import os
from billmyagent import PaymentClient, create_signer

# The private key is held in-process and never leaves it.
signer = create_signer("base", os.environ["PRIVATE_KEY"])
client = PaymentClient(signer=signer)

# client.http is a requests.Session; any HTTP 402 it hits is paid and retried.
res = client.http.get("https://api.example.com/paid-resource")
print(res.json(), "paid:", bool(res.headers.get("x-payment-response")))

Manage your merchant account (REST)

client = PaymentClient(api_key=os.environ["BMA_API_KEY"], auth_token=jwt)

client.get_payout_settings()
client.update_payout_settings({"base_address": "0x…"})
client.list_payments()

Charge for your endpoints (seller)

FastAPI:

from fastapi import FastAPI
from billmyagent.middleware.fastapi import add_payment_middleware

app = FastAPI()
add_payment_middleware(
    app,
    pay_to="0xYourPayoutAddress",
    routes={"GET /premium": "$0.01"},
    network="base-sepolia",   # base | base-sepolia
)

@app.get("/premium")
def premium():
    return {"unlocked": True}

Flask is identical via billmyagent.middleware.flask.add_payment_middleware.

Mainnet (base) settlement needs a facilitator with CDP credentials — pass facilitator_url=.... Omit it to use the public x402.org testnet facilitator.

Supported networks

EVM only, exact scheme: base, base-sepolia (testing).

Development

pip install -e '.[dev,fastapi,flask]'
pytest && ruff check . && mypy billmyagent

License

Apache 2.0.