x402 on Algorand - Python

Build x402 HTTP-native payment applications on Algorand with Python. Use the reference files below for detailed guidance on each component.

Python Quick Start

The x402-avm package on PyPI bundles core protocol, AVM mechanism, HTTP clients, and server middleware. Pick the extras you need:

# AVM only (no HTTP client/server)
pip install "x402-avm[avm]"

# Server middleware (pick one)
pip install "x402-avm[fastapi,avm]"    # FastAPI async
pip install "x402-avm[flask,avm]"      # Flask sync

# HTTP clients (pick one)
pip install "x402-avm[httpx,avm]"      # Async with httpx
pip install "x402-avm[requests,avm]"   # Sync with requests

# Bazaar discovery extension
pip install "x402-avm[extensions,avm]"

# Everything
pip install "x402-avm[all]"

Distribution name is x402-avm but the import root is x402 (not x402_avm).

Warning: Do not install the canonical PyPI x402 package in the same environment as x402-avm — both unpack into the same site-packages/x402 directory, and canonical x402 contains no AVM mechanism. Keep them in separate environments.

Register AVM Scheme

Every component registers the AVM exact scheme unconditionally — no environment variable guards:

# Client
from x402 import x402Client
from x402.mechanisms.avm.exact import ExactAvmScheme

client = x402Client()
client.register("algorand:*", ExactAvmScheme(signer=my_signer))

# Server
from x402.server import x402ResourceServer
from x402.mechanisms.avm.exact import ExactAvmServerScheme

server = x402ResourceServer()
server.register("algorand:*", ExactAvmServerScheme())

# Facilitator
from x402 import x402Facilitator
from x402.mechanisms.avm import ALGORAND_TESTNET_CAIP2
from x402.mechanisms.avm.exact import ExactAvmFacilitatorScheme

facilitator = x402Facilitator()
facilitator.register([ALGORAND_TESTNET_CAIP2], ExactAvmFacilitatorScheme(signer=my_signer))

x402Facilitator.register takes a list of networks, while x402Client.register and x402ResourceServer.register take a single string (glob "algorand:*" is fine there). Passing a bare string to the facilitator silently iterates it into single-character networks.

The register_exact_avm_client/server/facilitator helpers from x402.mechanisms.avm.exact are also valid.

Network identifiers

Always use the constants from x402.mechanisms.avm (ALGORAND_TESTNET_CAIP2, ALGORAND_MAINNET_CAIP2) rather than hardcoding CAIP-2 strings. As of x402-avm 2.0.2 these are the full genesis hash form (algorand:SGO1GKSzyE7IEPItTxCByw9x8FmnrCDexi9/cOUJOiI= for TestNet, algorand:wGHE2Pwdvd7S12BL5FaOP20EGYesN73ktiC1qzkkit8= for MainNet). The TypeScript @x402/avm package ≥2.20.0 uses the 32-char form (algorand:SGO1GKSzyE7IEPItTxCByw9x8FmnrCDe, algorand:wGHE2Pwdvd7S12BL5FaOP20EGYesN73k) — a TS server/client and a Python facilitator (or vice-versa) will not match until x402-avm adopts the same form.

Troubleshooting

macOS SSL errors reaching https://testnet-api.algonode.cloud: run with SSL_CERT_FILE=$(python -c "import certifi;print(certifi.where())").

Python algosdk Encoding

Python algosdk's msgpack_decode() expects base64 strings, msgpack_encode() returns base64 strings. Boundary conversion: msgpack_decode(base64.b64encode(raw_bytes).decode()) / base64.b64decode(msgpack_encode(obj)).

Reference Guide

Navigate to the appropriate reference based on your task. Each topic has three files:

{name}.md — Step-by-step implementation guide
{name}-reference.md — API details and type signatures
{name}-examples.md — Complete, runnable code samples

Explaining x402 for Python

Understand the x402-avm Python package structure, extras installation ([avm], [fastapi], [flask], [httpx], [requests], [extensions], [all]), signer protocols, async vs sync variants, and algosdk encoding boundaries.

explain-algorand-x402-python.md — Package ecosystem explanation
explain-algorand-x402-python-reference.md — API reference for the x402-avm package
explain-algorand-x402-python-examples.md — Python pattern examples

Building Clients

Build HTTP clients with httpx (async) or requests (sync) that automatically handle 402 payments. Covers wrapHttpxWithPayment, wrapRequestsWithPayment, ClientAvmSigner for payment signing.

create-python-x402-client.md — Client creation guide
create-python-x402-client-reference.md — httpx/requests API reference
create-python-x402-client-examples.md — Client code examples

Building Servers

Build payment-protected servers with FastAPI (async) or Flask (sync) middleware. Covers route pricing, PaymentMiddlewareASGI, Flask PaymentMiddleware, and multi-network support.

create-python-x402-server.md — Server creation guide
create-python-x402-server-reference.md — FastAPI/Flask middleware API reference
create-python-x402-server-examples.md — Server code examples

Building Facilitators and Bazaar Discovery

Build facilitator services that verify and settle Algorand payments on-chain. Covers FacilitatorAvmSigner protocol, register_exact_avm_facilitator, FastAPI facilitator endpoints (/verify, /settle, /supported), and Bazaar discovery extension for automatic cataloging and indexing of payment-gated APIs (declare_discovery_extension, extract_discovery_info, bazaar_resource_server_extension).

create-python-x402-facilitator.md — Facilitator creation guide (includes Bazaar setup in Steps 6-10)
create-python-x402-facilitator-reference.md — Facilitator + Bazaar API reference
create-python-x402-facilitator-examples.md — Facilitator + Bazaar code examples

Low-Level SDK Usage

Use x402-avm core components and AVM mechanism directly for custom integrations. Covers x402Client, x402ResourceServer, x402Facilitator, AVM signer protocols, constants, utilities, transaction encoding, and fee abstraction.

use-python-x402-core-avm.md — Core SDK usage guide
use-python-x402-core-avm-reference.md — Core/AVM API reference
use-python-x402-core-avm-examples.md — Core SDK code examples

Python Package Quick Reference

One PyPI distribution (x402-avm) provides everything via extras. Import root is x402.

| Install spec | Purpose | | ------------ | ------- | | x402-avm[avm] | Core protocol + Algorand SDK (py-algorand-sdk) | | x402-avm[httpx,avm] | Async HTTP client wrapper (httpx) with automatic 402 payment handling | | x402-avm[requests,avm] | Sync HTTP client wrapper (requests) with automatic 402 payment handling | | x402-avm[fastapi,avm] | FastAPI async payment middleware | | x402-avm[flask,avm] | Flask sync payment middleware | | x402-avm[extensions,avm] | Bazaar discovery extension | | x402-avm[all] | All extras (EVM, SVM, AVM, all servers and clients, extensions) |

How to Use This Skill

Start here to understand which reference you need
Read the {name}.md file for step-by-step implementation guidance
Consult {name}-reference.md for API details
Use {name}-examples.md for complete, runnable code samples