Drop-in libraries to add or consume x402 payments.
An SDK hides the x402 handshake behind a few lines of code: middleware for servers, a client wrapper for the agent side. These libraries span languages and frameworks so you can integrate pay-per-request quickly — and are cross-listed in the per-language categories when they target one stack specifically.
Below are the x402 SDKs and client libraries in the directory.
Real projects from the directory · stars live from GitHub · sorted by popularity. Showing the top 60 of 174.
An open SDK for agentic payments. Let AI agents make payments, hold funds, and move money across chains with policy enforcement and human approval built in.
Client SDK for the Vybe x402 API. Pay-per-call USDC over HTTP and prepaid-credit WebSocket streaming for Vybe's Solana analytics API. Built for AI agents.
Building blocks for Agentic payments (x402, MPP, AP2) for TypeScript, Rust, Go, Python, Ruby, PHP, Lua, Kotlin and Swift.
Opinionated React Native crypto x AI chat app boilerplate with embedded wallet support, conversational AI, and dynamic UI component injection
A fully modular, framework-agnostic, easy-to-extend SDK for building complex X402 payment integrations.
The neutral micropayment router for autonomous agents. A single HTTP client that intercepts '402 Payment Required', routes across x402, L402, and MPP, persists credentials as recoverable assets, enforces per-envelope budgets, and emits a structured trace.
AI-powered flood intelligence system featuring h2oGPTe Agent + NVIDIA NIM integration (A2A), NAT pipeline with Nemotron 49B, and real-time flood risk assessment. Part of NVIDIA–H2O.ai AI for Good Blueprint for disaster response and monitoring.
xgrain402 delivers production-ready payment processing capabilities built specifically for the BSC ecosystem
Tooling for building applications with x402 payment capabilities. Supports buyer and seller roles.
Elixir implementation of the Agent-to-Agent (A2A) protocol (https://a2a-protocol.org).
Developer integration tools for adding TDM payments to AI agents, apps, and workflows. CLI, MCP server, and copy-paste examples
Open contract-facing SDK for payable routes and gateway-backed integrations. Thin public surface for authorize, checkout, and session flows.
Developer integration tools for adding TDM payments to AI agents, apps, and workflows. CLI, MCP server, and copy-paste examples
The open-source toolkit for building AI commerce agents using UCP and ACP protocols
Add x402 payment support to your API in seconds. Easily accept x402 payments and sell one-time API access—all with a single configuration and no changes to your existing codebase.
TypeScript & Python middleware to make any REST endpoint x402-compatible. Wrap, verify, and settle USDC payments on Base in minutes.
Official TypeScript/Node.js SDKs for the InFlow payments platform - x402 and MPP (Machine Payments Protocol) integration for sellers and buyers.
An x402 / agent-payment project in the SDKs & Clients category.
the onramp for pay-as-you-go decentralized storage on IPFS — SOL, USDFC, USDC, and x402 agent payments
x402 (HTTP 402 Payment Required) SDK + MCP server: let any API charge for itself and any AI agent pay for itself, USDC & stablecoins across EVM, Solana & 8 more chain families, in a couple of lines. Backendless, no fee, self-custodial, paid straight to your wallet. TypeScript, MIT.
The open authority layer + SDKs for AI-agent payments. Thin Python/TS clients, an MCP server, framework adapters (LangChain/CrewAI/Hermes/OpenClaw/…), and @sardis/reference — a pure policy simulator + AP2/TAP/x402 verifiers showing exactly how Sardis decides if an agent may spend. The hosted engine that moves money is private.
HTTP 402 payments for Solana. A zero-trust middleware to protect API routes and settle payments directly on-chain.
Unified payment execution layer for Stellar x402, MPP charge, MPP session behind one client.pay() call
Trust & reputation layer for AI agents. Agent Credit Score (300-850) + Merkle-anchored ledger + behavioral finance + EWMA anomaly detection. Memory + payments + identity + fraud in one SDK. npm i @mnemopay/sdk
Official Python SDK: Multi-agent payments, x402 Auto-Pay, and Base L2/USDC support.
Give your AI agents a fetch() that pays. Multi-protocol, multi-chain, open source.
Express middleware for payment-gated MCP servers — multi-network X402 support with automatic routing, simulation, and JSON-RPC 402 compliance.
Build paid APIs, agents, tools & data feeds on the DNA x402 hosted rail. Templates, Degen Mode, no backend custody. Public Beta.
Consensus Protocol proxy, WebSocket and tunnel service supporting x402 payments.
Non-custodial crypto wallets for AI agents with on-chain spending limits. ERC-6551, x402 compatible, Base Mainnet.
Official documentation for {xpay✦}. Learn how to monetize, manage, and observe your AI agents using the x402 protocol.
OpenClaw plugins that add A2A compatibility and enable communication with other A2A-compatible agents.
@vanarchain/xbpp — Execution Boundary Permission Protocol SDK for AI agent payments
TypeScript SDK for private x402 payments on Solana - Groth16 ZK proofs, ElGamal-encrypted amounts, on-chain PDA escrow, agent autopay.
TypeScript SDK for the x402 payment protocol — client signing, server paywall, and facilitator integration for EVM and TRON
An open-source library for AI-native x402 integrations in the Solana ecosystem. Built for Python and Node.js, distributed via PyPI and npm, with server implementations for FastAPI and Express.js. Accelerate.
Trust infrastructure for the agent economy — classify, score, and price every AI agent request with World ID, AgentKit, x402, and XMTP
FastAPI middleware for Machine Payments Protocol (MPP). Add 402 Payment Required challenges, secure sessions, and receipt validation to your APIs for AI agents.
Official Node.js SDK for interacting with the x402 AI Frens API. This SDK enables you to chat with AI agents, generate images, videos, and memes using blockchain-based payments.
An autonomous AI agent framework for Cronos zkEVM that bridges social intelligence with on-chain safety using x402 payment handshakes and institutional-grade Sentinel guardrails.
Go SDK for the x402 payment protocol — client signing, server paywall middleware, and facilitator
SNAP - Signed Network Agent Protocol. Secure agent-to-agent (A2A) communication with cryptographic identity, built on Bitcoin Schnorr signatures and Nostr.
Give your agent a spending limit it can't exceed. Non-custodial tabs on Solana, plus one-shot x402 across the major EVM chains. Buyer + seller SDKs.
Use x402 payments into your apps: fetch requirements, sign, and send transactions.
A2A PHP SDK - PHP implementation of the AI A2A (Agent-to-Agent) Protocol (v0.2.5-0.3.0)
Runtime security middleware for A2A (Agent-to-Agent) protocol agents. Provides always-on validation, signature verification, and rate limiting for AI agent interactions.
x402 Payment Protocol SDKs - Dead simple micropayments for APIs and AI agents
A set of Ethereum-compatible smart contracts that standardize status codes, policy checks, and intent validation for Web3 transactions, designed to integrate cleanly with an HTTP/x402 gateway and agent layer.
Non-custodial payment protocol for AI agents on Solana — capability-scoped intents, on-chain verification, and signed receipts. Everything x402 should have been.
Official builder for the Summoner SDK (multi-repo merge + uv/pip install)
x402 service provider tooling for Azeth — gate Hono endpoints behind x402 payments
Automatic micro-donations powered by x402. Drop-in Express/Next.js middleware that sends USDC to charities on every user action. npm install x402charity.
We currently track 174 SDKs & Clients SDKs in the directory, drawn from open-source repositories building on x402 and agent payments. The list above is sorted by GitHub stars and updates as new projects are submitted and crawled.
x402 is an open standard for paying for an HTTP resource: a server replies with HTTP 402 and payment terms, the client pays (usually USDC), and the request is fulfilled. The SDKs & Clients SDKs above implement or build on this flow.
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