# PayAI > PayAI is the x402 payment facilitator for AI agents and apps. It verifies and settles stablecoin micropayments over HTTP across Solana, Base, Polygon, Avalanche, Arbitrum, Sei, X Layer, and SKALE — so a service can charge per request and an agent can pay for one, without accounts or API keys. ## When to use PayAI PayAI is an [x402](https://docs.payai.network/x402/introduction) payment facilitator. x402 revives the HTTP `402 Payment Required` status code: a server answers an unpaid request with `402` and machine-readable payment terms, the client signs a stablecoin payment, and the facilitator verifies and settles it on-chain. No accounts, no API keys, no card on file, no human in the loop. Reach for PayAI when you are doing any of these: - **Charging for an API, MCP tool, or agent service per request.** Put x402 middleware in front of a route and point it at `https://facilitator.payai.network`. You get paid in USDC per call, with no signup flow for your buyers. Start at https://docs.payai.network/x402/servers/introduction. - **Paying for a resource that returned HTTP 402.** Use an x402 client SDK; it reads the payment requirements, signs, and retries. Start at https://docs.payai.network/x402/clients/introduction. - **Finding services an agent can buy right now.** Query `GET https://facilitator.payai.network/discovery/resources` for the live catalog of x402-payable HTTP endpoints and MCP tools, including their payment terms and, where published, their input and output schemas. - **Settling agent payments on Solana.** PayAI is Solana-first and sponsors gas, so the payer needs only USDC — no SOL for fees. It also settles on Base, Polygon, Avalanche, Arbitrum, Sei, X Layer, and SKALE. - **Checking which chains and schemes are live** before advertising payment terms: `GET https://facilitator.payai.network/supported`. - **Testing an x402 integration end to end** against a real merchant that returns 402: https://x402.payai.network. Do not use PayAI for: card payments, fiat payouts, bank transfers, custody of user funds, or subscription billing. PayAI settles stablecoin micropayments over HTTP; it is not a payment processor for consumer checkout and it never holds merchant balances. ## How an agent should call PayAI 1. Read the developer portal at https://payai.network/developers, or the OpenAPI description at https://payai.network/openapi.json — it documents every public facilitator operation with typed request and response schemas. 2. Call `GET https://facilitator.payai.network/supported` to pick a live network and scheme. 3. Call `POST https://facilitator.payai.network/verify` to check a signed payment, then `POST https://facilitator.payai.network/settle` to move funds. 4. Errors are always JSON. `/verify` returns `{ isValid: false, invalidReason, invalidMessage }`; `/settle` returns `{ success: false, errorReason, errorMessage, transaction, network, payer }`. Treat `errorReason: "settlement_pending"` as unresolved rather than failed, and re-submit the identical body to poll for the outcome. `GET` endpoints need no authentication. `POST /verify` and `POST /settle` take an optional `Authorization: Bearer ` for credit accounting and dedicated rate lanes; without one you are served on the free tier. Keys come from https://merchant.payai.network. ## Developer resources - [PayAI developer portal](https://payai.network/developers): endpoints, authentication, error model, versioning, and quickstarts in one page. - [PayAI OpenAPI description](https://payai.network/openapi.json): OpenAPI 3.1 spec for the PayAI x402 Facilitator API — verify, settle, supported networks, and Bazaar discovery. - [PayAI Facilitator API](https://facilitator.payai.network): production facilitator endpoint. Point your x402 middleware or client here. - [PayAI documentation](https://docs.payai.network): quickstarts, protocol reference, and supported networks. - [PayAI MCP server](https://payai.network/mcp): Streamable HTTP MCP server for searching the PayAI docs corpus. No authentication. Also reachable at https://payai.network/.well-known/mcp and on its origin host at https://docs.payai.network/mcp. - [x402 quickstart](https://docs.payai.network/x402/quickstart): fastest path from zero to a paid request. - [Merchant quickstarts](https://docs.payai.network/x402/servers/introduction): Express, Hono, Next.js, FastAPI, Flask, and Gin. - [Client quickstarts](https://docs.payai.network/x402/clients/introduction): Axios, Fetch, httpx, requests, and Go net/http. - [Supported networks](https://docs.payai.network/x402/supported-networks): every chain and asset the facilitator settles. - [Facilitator pricing](https://docs.payai.network/x402/facilitators/pricing): free tier and per-transaction pricing. - [Merchant portal](https://merchant.payai.network): API keys, credits, usage, and auto top-up. - [x402 Echo Merchant](https://x402.payai.network): live test merchant that returns HTTP 402. - [GitHub](https://github.com/PayAINetwork): open-source SDKs, integrations, and examples. ## Site pages - [Home](https://payai.network/): what PayAI is, supported networks, and how to integrate. - [About PayAI](https://payai.network/about): what the company builds and who it is for. - [Contact](https://payai.network/contact): support, sales, security, and legal contacts. - [Developer portal](https://payai.network/developers): how to call the PayAI API. - [Ecosystem](https://payai.network/ecosystem): projects building on PayAI and x402. - [Blog](https://blog.payai.network): product and ecosystem updates. - [Privacy policy](https://payai.network/privacy-policy) - [Terms of service](https://payai.network/terms-of-service) ## Machine-readable surfaces - [llms-full.txt](https://payai.network/llms-full.txt): this guide plus the full text of every page on this site. - [Sitemap index](https://payai.network/sitemap_index.xml): covers payai.network, blog, and docs. - [MCP manifest](https://payai.network/.well-known/mcp.json) - [AI catalog](https://payai.network/.well-known/ai-catalog.json) - [API catalog (RFC 9727)](https://payai.network/.well-known/api-catalog) - [MCP registry manifest](https://payai.network/server.json) Every content page on this site also serves Markdown. Request it with `Accept: text/markdown`, or append `.md` to the path (for example https://payai.network/about.md). ## Contact - Email: info@payai.network - Discord: https://discord.gg/eWJRwMpebQ - X: https://x.com/PayAINetwork --- # Full page contents --- # Source: https://payai.network/ # PayAI — the x402 Facilitator for AI Agents and Apps Accept agentic payments on every major chain with one integration. Multi-chain micropayments powered by Solana, with no API keys, no accounts, and instant settlement. ## What PayAI does PayAI is a facilitator for the [x402 payment standard](https://docs.payai.network/x402/introduction). x402 uses the HTTP `402 Payment Required` status code to make payment a property of a request: a server answers an unpaid request with `402` plus machine-readable payment terms, the client signs a stablecoin payment, and the facilitator verifies and settles it on-chain. As the facilitator, PayAI takes the blockchain work off both sides. A merchant does not run an RPC node, hold a private key, manage nonces, or reconcile settlements. A buyer does not create an account or hold native gas tokens — PayAI sponsors gas on Solana, so a payer needs only USDC. - **Pay-per-request pricing.** Charge per request, action, or unit of usage — suited to APIs, AI agents, and real-time services. - **Instant settlement.** Payments verify and settle in under a second, with no manual reconciliation. - **Client and agent payments.** The same rail serves human web flows and autonomous agents. - **x402 standard adoption.** Adopt x402 without handling chain selection, gas, fee logic, or settlement. Payments range from $0.01 to $1,000,000: microtransactions for AI agents, one-time digital-content sales, and recurring SaaS charges all use the same endpoint. ## Supported networks PayAI is Solana-first and also settles on Base, Polygon, Avalanche, Arbitrum, Sei, X Layer, and SKALE, on both mainnet and the corresponding testnets. Both x402 v1 short network names (`base`, `solana`) and x402 v2 CAIP-2 identifiers (`eip155:8453`, `solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp`) are supported. For the authoritative live list, call `GET https://facilitator.payai.network/supported` — it returns every (x402 version, scheme, network) combination the facilitator can currently verify and settle. The documented list is at https://docs.payai.network/x402/supported-networks. ## Integrate Point x402 middleware or an x402 client at the facilitator: ``` https://facilitator.payai.network ``` - Merchants (accept payments): https://docs.payai.network/x402/servers/introduction — quickstarts for Express, Hono, Next.js, FastAPI, Flask, and Gin. - Clients and agents (make payments): https://docs.payai.network/x402/clients/introduction — quickstarts for Axios, Fetch, httpx, requests, and Go net/http. - Quickstart: https://docs.payai.network/x402/quickstart - API reference: https://payai.network/openapi.json ## Products - **x402 Facilitator** — live. Accept payments from $0.01 to $1,000,000 across every supported network. - **x402 Echo Merchant** — live. Run real x402 transactions against a live merchant for free; test payments are fully refunded and PayAI covers network fees. https://x402.payai.network - **Payment Splitting** — coming soon. Receive payments to one account and distribute to multiple recipients, for marketplaces and multi-party workflows. - **Token Gateway** — coming soon. Cross-network payments, so buyers can pay from whichever chain they hold funds on. ## Discovery: the PayAI Bazaar PayAI indexes the services that accept x402 payments. `GET https://facilitator.payai.network/discovery/resources` returns the live catalog — HTTP endpoints and MCP tools, each with the payment terms needed to call it and, where the seller published them, input and output schemas. `GET https://facilitator.payai.network/discovery/stats` returns aggregate catalog size, settlement counts, and per-network volume. ## Frequently asked questions ### What is x402? x402 is an open payment standard built on the HTTP 402 Payment Required status code. A server answers an unpaid request with 402 and machine-readable payment terms; the client signs a stablecoin payment and retries; a facilitator verifies and settles it on-chain. It lets AI agents, apps, and platforms send and receive micropayments instantly across multiple blockchains, with no accounts, API keys, or checkout flow. ### How fast are transactions on x402? Payments are verified and settled in under a second on PayAI's supported networks, which is what makes x402 usable for per-request pricing. Settlement is confirmed on-chain rather than promised, so a merchant can serve the paid resource immediately after PayAI returns success. If a settlement outruns its response budget, PayAI returns the broadcast transaction hash with a settlement_pending status so the payment can be reconciled instead of silently lost. ### Which chains does x402 support? PayAI settles on Solana, Base, Polygon, Avalanche, Arbitrum, Sei, X Layer, and SKALE, across both mainnet and testnets. Solana carries most production volume because it is the cheapest and fastest place to settle a sub-cent payment, and PayAI sponsors the network fee there so payers need only USDC. Call GET https://facilitator.payai.network/supported for the authoritative live list. ### What is the minimum payment amount? There is no protocol minimum. PayAI settles amounts from $0.01 to $1,000,000 through the same endpoint, so you can charge a fraction of a cent per API call or thousands of dollars for a one-time purchase. In practice the floor is set by the network fee on your chosen chain, which is why Solana is the default for high-frequency micropayments. ### How can developers integrate x402 into their app? Point x402 middleware or an x402 client at https://facilitator.payai.network. Merchants add a few lines to an existing route — quickstarts exist for Express, Hono, Next.js, FastAPI, Flask, and Gin. Clients and agents use an x402-aware HTTP client such as Axios, Fetch, httpx, requests, or Go net/http, which reads the 402 response, signs, and retries automatically. You never manage wallets, RPC nodes, gas, or settlement logic. The full API is described at https://payai.network/openapi.json. ### Do I need an account or API key to use PayAI? No. Verification and settlement work without any PayAI relationship, and buyers never sign up to pay a PayAI-backed merchant. An API key is optional and only affects credit accounting, dedicated throughput lanes, and usage analytics. You can create one in the merchant portal at https://merchant.payai.network when you want those, and keep using the free tier until then. ### What does PayAI cost? PayAI has a free tier that covers ordinary integration and testing volume, after which settlement is billed per transaction from a prepaid credit balance rather than as a percentage of the amount moved — a flat per-settlement cost is what makes sub-cent payments viable. Rates vary by network, because the underlying chain fee does. Current rates and free-tier limits are published at https://docs.payai.network/x402/facilitators/pricing, and you can top up credits (or enable automatic top-up) in the merchant portal. ### What happens if a payment fails or a settlement times out? Verification and settlement return structured JSON on every outcome, including errors, so failures are machine-readable rather than something to parse out of an HTML page. If a settlement outruns its response budget, PayAI answers with errorReason settlement_pending and the broadcast transaction hash — the payment may still land, so treat it as unresolved rather than failed and re-submit the identical request to poll for the real result. Settlement is idempotent per payment, so retrying cannot double-charge. ### How do agents discover services that accept x402 payments? Query GET https://facilitator.payai.network/discovery/resources. It returns the PayAI Bazaar: a live catalog of HTTP endpoints and MCP tools that accept x402 payments, each with the payment terms an agent needs to construct a payment and, where the seller published them, input and output schemas so the resource can be called as a tool. ### Is x402 secure? Payments are cryptographically signed by the payer and settled on-chain, so every transaction is verifiable and tamper-resistant, and a facilitator can never move more than the payer authorized. PayAI verifies the signature, the amount, the network, and the payer's balance before settling, screens transactions for compliance, and fails closed rather than settling when a dependency is unavailable. Settlement is idempotent per payment, so a retried request cannot double-charge. ## More from PayAI - Documentation: https://docs.payai.network - OpenAPI description: https://payai.network/openapi.json - Facilitator API: https://facilitator.payai.network - Agent guide: https://payai.network/llms.txt - Blog: https://blog.payai.network - GitHub: https://github.com/PayAINetwork - Support: info@payai.network --- # Source: https://payai.network/about # About PayAI PayAI builds payment infrastructure for software that transacts without a human in the loop. ## What we build PayAI operates a production facilitator for the [x402 protocol](https://docs.payai.network/x402/introduction). x402 turns the long-dormant HTTP `402 Payment Required` status code into a working payment handshake: a server answers an unpaid request with `402` and machine-readable terms, the client signs a stablecoin payment, and a facilitator verifies and settles it on-chain. The whole exchange is two HTTP round trips, and neither side needs an account with the other. The facilitator is the part that touches the chain. PayAI verifies signed payment payloads, broadcasts settlements, sponsors gas where the chain allows it, screens for compliance, and returns a structured result — so a merchant integrates payments as middleware rather than as a blockchain project. ## Why this matters Existing payment rails assume a human: a card to enter, an account to create, a checkout to complete, a chargeback window to wait out. Autonomous software has none of those. It needs to pay for a single API call, immediately, for a fraction of a cent, without onboarding. That is the gap PayAI fills. An agent that hits a paywalled endpoint can settle in under a second and continue. A service that wants to sell to agents can price per request instead of negotiating contracts. ## How we are different - **Solana-first, multi-chain in practice.** PayAI settles on Solana, Base, Polygon, Avalanche, Arbitrum, Sei, X Layer, and SKALE. Solana carries the majority of production volume because it is the cheapest and fastest place to settle a sub-cent payment. - **Gasless for the payer.** On Solana, PayAI sponsors the network fee. A payer holds USDC and nothing else — no native token, no top-up ritual. - **No accounts on the critical path.** A buyer needs no PayAI relationship to pay a PayAI-backed merchant. An API key is optional, and only affects credit accounting and rate lanes. - **Open and inspectable.** The SDKs, integrations, and examples are open source at https://github.com/PayAINetwork, and the facilitator API is fully described at https://payai.network/openapi.json. ## Who it is for Merchants selling API calls, MCP tools, inference, data, or compute to software buyers. Agent developers whose agents need to pay for things at runtime. Platforms that want usage-based pricing without building settlement infrastructure. ## The company PayAI Network, LLC is registered in Delaware, United States. The team works remotely. Reach us at https://payai.network/contact. ## More from PayAI - Documentation: https://docs.payai.network - OpenAPI description: https://payai.network/openapi.json - Facilitator API: https://facilitator.payai.network - Agent guide: https://payai.network/llms.txt - Blog: https://blog.payai.network - GitHub: https://github.com/PayAINetwork - Support: info@payai.network --- # Source: https://payai.network/contact # Contact PayAI PayAI is operated by PayAI Network, LLC, registered in Delaware, United States. The team works remotely; info@payai.network reaches us for anything below. ## Support Integration help, API questions, and bug reports. - Email: info@payai.network - Discord: https://discord.gg/eWJRwMpebQ — the community channel, and the quickest place to get eyes on an integration problem - Documentation: https://docs.payai.network - Service health: `GET https://facilitator.payai.network/health` Before opening a support request, check the quickstart at https://docs.payai.network/x402/quickstart and confirm your network is live via `GET https://facilitator.payai.network/supported`. ## Sales and partnerships Volume pricing, dedicated throughput, ecosystem listings, and integration partnerships. - Email: info@payai.network - Telegram: https://t.me/PayAINetwork - Partnership enquiry form: https://forms.gle/qi1eeb8X5Uu56erx6 - Ecosystem directory: https://payai.network/ecosystem ## Security Report a vulnerability privately to info@payai.network. Please do not open a public issue. The machine-readable version of this is at https://payai.network/.well-known/security.txt. ## Legal and privacy Questions about the terms, privacy practices, or data requests. - Email: legal@payai.network - Privacy policy: https://payai.network/privacy-policy - Terms of service: https://payai.network/terms-of-service ## Elsewhere - X: https://x.com/PayAINetwork - LinkedIn: https://www.linkedin.com/company/payai-network/ - GitHub: https://github.com/PayAINetwork - Telegram: https://t.me/PayAINetwork - Blog: https://blog.payai.network - Merchant portal: https://merchant.payai.network - MCP server: https://payai.network/mcp ## More from PayAI - Documentation: https://docs.payai.network - OpenAPI description: https://payai.network/openapi.json - Facilitator API: https://facilitator.payai.network - Agent guide: https://payai.network/llms.txt - Blog: https://blog.payai.network - GitHub: https://github.com/PayAINetwork - Support: info@payai.network --- # Source: https://payai.network/ecosystem # PayAI Ecosystem Projects building on PayAI and the x402 protocol: agents that pay, services that charge per request, and infrastructure that connects them. For the live, machine-readable catalog of services that currently accept x402 payments — including their payment terms and callable schemas — query `GET https://facilitator.payai.network/discovery/resources` instead of this page. This page lists ecosystem partners; that endpoint lists everything payable right now. ## Projects - **_done** _(AI Agents)_ — https://underscoredone.com _done offers pay-per-call tools and APIs for AI agents — including bulk DMARC lookups, domain age checks, HTTP status checks, and QR code generation — settled in USDC on Base via x402, with no accounts, API keys, or subscriptions. - **WURK.FUN** _(AI Agents)_ — https://wurk.fun WURK.FUN is a crypto-native microtask marketplace on Solana where AI agents hire humans for micro-jobs and users earn SOL and USDC by completing verified tasks via x402 payments. - **Pixel Games AI** _(Gaming)_ — https://pixelgames.ai/ Pixel Games AI uses PayAI to support instant in-game transactions and AI-driven gameplay services in the Web3 gaming space. - **x402 Monopoly** _(Gaming)_ — https://www.x402monopoly.com x402 Monopoly showcases pay-per-action payments in a game environment using the x402 standard. - **Predict** _(AI Agents)_ — https://predict.fun Predict is the BNB-native prediction market where users trade real-world event outcomes using USDT and other stable assets, with collateral that can earn yield while positions stay open. - **EarnFi** _(Blockchain)_ — https://earnfi.fun EarnFi is a Web3 rewards platform that helps users discover, track, and manage on-chain incentives. - **Skale** _(Blockchain)_ — https://www.skale.space Skale is a high-performance blockchain network built for scalable and gas-free decentralized applications. - **Blips** _(Analytics)_ — https://blips.run Blips is an analytics and growth platform offering metrics, campaigns, launches, and incubation for token projects across Solana launchpads. - **NOFA AI** _(Trading)_ — https://www.nofa.ai NOFA AI is an autonomous trading platform that brings real market execution to AI agents, offering a no-code Agent Studio, live execution layer, and institutional-grade risk management powered by Aster and Binance. - **t54 AI** _(AI Agents)_ — https://www.t54.ai t54 Labs is building a trust layer for the agentic economy, providing AI agent identity verification, real-time risk controls, and settlement infrastructure, backed by Ripple and Franklin Templeton. - **DIRA Network** _(AI Agents)_ — https://aiagentsdirectory.com DIRA Network is the world's largest AI agents marketplace and directory, enabling users to discover, test, and scale AI agents while integrating x402 payments and ERC-8004 identity for on-chain agent access. - **AiMo Network** _(AI Agents)_ — https://aimo.network AiMo Network is agent-native middleware providing permissionless access to hundreds of AI models through a single OpenAI-compatible API, with transparent blockchain-based x402 pay-per-use payments. - **Canza** _(DeFi)_ — https://canza.app Canza is an AI-powered Web3 trading dashboard with customizable widgets, real-time market data, and seamless Solana wallet integration for DeFi management. - **Compute3** _(Infrastructure)_ — https://compute3.ai Compute3 provides enterprise GPU infrastructure for AI workloads, offering per-second billing and Docker-based orchestration with access to GPUs ranging from L4 to B300 and zero vendor lock-in. - **Gloria AI** _(AI Agents)_ — https://itsgloria.ai Gloria AI is an AI-powered news intelligence platform providing real-time sentiment analysis and market intelligence with API, bot, and MCP integrations. - **Nansen** _(Analytics)_ — https://nansen.ai Nansen is a blockchain analytics platform that enriches on-chain data with millions of wallet labels to help users discover trading opportunities, conduct due diligence, and monitor portfolios. - **Syraa** _(AI Agents)_ — https://syraa.fun Syraa is an AI trading infrastructure layer providing institutional-grade trading tools including real-time sentiment analysis, risk scoring, and automated execution. - **Voxight** _(AI Agents)_ — https://voxight.online Voxight transforms Twitter Spaces into AI-powered summaries using OpenAI Whisper for transcription, delivering intelligent recaps via x402 micropayments at 1 USDC per summary. - **Xona Agent** _(AI Agents)_ — https://xona-agent.com Xona is a creative AI agent built on the x402 payment protocol, offering pay-per-use access to AI-powered image generation, video creation, and content analysis tools. - **GPThree** _(AI Agents)_ — https://gpthree.ai GPThree is an AI agent platform that provides AI-powered services and tools for the Web3 ecosystem, integrated with the x402 payment protocol. - **RelAI** _(DeFi)_ — https://relai.fi Relai is an x402 API marketplace that enables developers to monetize APIs with instant micropayments on Solana, Base, Avalanche, SKALE, Ethereum, and Polygon, with built-in custodial wallets and MCP support. - **Jatevo** _(AI Agents)_ — https://jatevo.ai Jatevo is a decentralized GPU LLM inference network that routes prompts across distributed GPU nodes for low-latency, cost-efficient hosting of frontier open-source language models. - **PinionOS** _(Infrastructure)_ — https://pinionos.com PinionOS is a client SDK, Claude Code plugin, and skill server framework for the Pinion protocol, enabling x402 micropayments on Base so agents can call on-chain skills without managing payments. - **Tip.md** _(Payments)_ — https://tip.md Tip.md lets developers and creators add crypto tipping buttons to GitHub READMEs and markdown content, supporting multi-chain tips on Ethereum, Solana, and Bitcoin Lightning. - **x420** _(Infrastructure)_ — https://x420.dev x420 is a token launchpad on Base that implements HTTP 420 ("Enhance Your Calm") as a rate-limiting protocol, allowing AI agents and web services to negotiate cooldown periods as a complement to x402 payments. - **Serpent** _(AI Agents)_ — https://www.discoverserpent.com Serpent is the credibility layer for early-stage projects and builders on Solana, combining curator insights with on-chain data to surface real builders and high-potential projects before the crowd catches on. - **MilyPay** _(Infrastructure)_ — https://milypay.xyz MilyPay is an x402 service provider offering Australian data APIs — business identity, property, weather, and civic information — with pay-per-call settlement in AUDD, a regulated AUD-native stablecoin on Solana, letting AI agents access data without API keys or signup. - **8004scan** _(Analytics)_ — https://www.8004scan.io 8004scan is a blockchain explorer for ERC-8004 AI agents, letting users discover, create, and interact with autonomous agents while tracking identity registries, reputation, and network activity. - **x402wall** _(Infrastructure)_ — https://x402wall.fun x402wall is a permanent advertising grid on Solana where users buy brick-sized ad slots for 1 USDC each via x402 payments, with permanent ownership and the ability to resell on a marketplace. - **Engrave Protocol** _(Infrastructure)_ — https://engrave-protocol.ai Engrave Protocol provides BTCFi tools for AI agents, offering real-time Bitcoin blockchain data access via MCP with pay-per-request USDC micropayments on Solana using the x402 protocol. - **QuickSync** _(Infrastructure)_ — https://quicksync.me QuickSync is a privacy-first, decentralized platform for sharing, building, and monetizing digital experiences using zero-knowledge encryption and Web3 APIs without middlemen or surveillance. - **Holoworld AI** _(AI Agents)_ — https://www.holoworldai.com Holoworld AI is a platform for creating intelligent virtual characters with customizable personalities and knowledge bases, enabling AI-powered storytelling across Discord, Telegram, YouTube, and more. - **Cascade** _(AI Agents)_ — https://cascade.fyi Cascade is a permissionless automatic payment splitting protocol for Solana with a non-custodial design and a 1% protocol fee. - **Readia** _(AI Agents)_ — https://www.readia.io Readia brings x402 payments to any content platform, enabling agentic commerce in minutes with a multi-chain SDK offering peer-to-peer instant settlement for the new content economy. - **OOBE** _(AI Agents)_ — https://www.oobeprotocol.ai OOBE Protocol is a Solana-native framework for building, deploying, and monetizing AI agents on-chain with no coding required, featuring conversational memory, parallel function execution, and smart tool selection. - **Migrate.fun** _(DeFi)_ — https://www.migratefun.com Migrate.fun is a token migration platform on Solana that lets projects transition tokens to new contracts with automated liquidity pool creation, safeguarded migrations, and refund mechanisms. - **Stellar** _(Blockchain)_ — https://stellar.org Stellar is a decentralized Layer-1 blockchain network for fast, low-cost payments and asset tokenization, backed by the nonprofit Stellar Development Foundation. - **Polygon** _(Blockchain)_ — https://polygon.technology Polygon is a leading Ethereum-compatible blockchain platform for scalable, low-cost transactions with near-instant finality, widely adopted for DeFi, gaming, and payments. - **SOON** _(Blockchain)_ — https://soo.network SOON (Solana Optimistic Network) is a high-performance SVM rollup stack built on the OP Stack, delivering 30,000+ TPS with 50ms block times and enabling SVM Layer-2 deployment on any Layer-1. - **Blockrun** _(Infrastructure)_ — https://blockrun.ai Blockrun is a pay-as-you-go AI gateway that routes requests to the cheapest capable LLM across 30+ models via x402 payments on Base, Solana, and XRPL, claiming to save 78% on LLM costs. - **Gradient** _(AI Agents)_ — https://gradient.network Gradient is building the first fully distributed AI runtime on Solana, a peer-powered infrastructure where intelligence is hosted, served, and owned by the people through the Open Intelligence Stack. - **1ly** _(SaaS)_ — https://1ly.store 1ly turns any link into an instant paid product using the x402 protocol, enabling developers, creators, and AI agents to monetize APIs and digital content with USDC on Base and Solana. - **Lucid** _(AI Agents)_ — https://www.lucidlabs.fi Lucid is a multi-bridge liquidity hub combining x402 and ERC-8004 to give AI agents identity, payment capability, and autonomous operation across multiple chains. - **Mind Network** _(AI Agents)_ — https://www.mindnetwork.xyz Mind Network pioneers Fully Homomorphic Encryption (FHE) infrastructure for Web3, enabling quantum-resistant, fully encrypted data and AI computation with the HTTPZ zero-trust protocol. - **HYRE Agent** _(AI Agents)_ — https://hyreagent.fun HYRE Agent is an AI-enhanced DeFi intelligence API with 24 pay-per-call endpoints. It uses x402 protocol every response includes LLM-interpreted insights with confidence-scored signals with no API keys needed, payment is the only gate for agent society era. - **Utilia** _(Infrastructure)_ — https://utilia.ink Utilia provides machine-payable Solana transaction simulation, diagnostics, priority-fee estimates, and token-risk analysis over x402 v2 and remote MCP. Agents pay $0.002–$0.008 USDC per result through PayAI with no account, subscription, or API key; an open-source npm client handles wallet-funded calls locally. - **ManyHands Evidence API** _(SaaS)_ — https://manyhands.uk/evidence-api/ ManyHands provides deterministic evidence operations over public UK official sources, including snapshots, change checks, deadline scans, citation packs, and PDF evidence. Its paid API uses x402 v2 USDC on Base, with public documentation and per-call pricing from $0.01 to $0.05. - **PulseNetwork** _(AI Agents)_ — https://pulse.theaslangroupllc.com PulseNetwork is a fleet of 75 pay-per-call data APIs for AI agents: 900+ x402 endpoints covering token safety, crypto, macro, sports, travel, climate, and more, settled in stablecoins on Solana, Base, and other supported networks. No accounts, API keys, or subscriptions. - **ByKaranteli** _(Analytics)_ — https://bykaranteli.com ByKaranteli is a crypto derivatives data terminal that turns multi-exchange liquidation maps, funding and open-interest history, Deribit options flow, CFTC COT positioning and VPIN order-flow toxicity into machine-callable endpoints. 13 of them are x402 pay-per-call at $0.002 to $0.010 USDC on Solana and Base mainnet, settled through the Coinbase CDP facilitator, with no account, subscription or API key: free catalog at https://bykaranteli.com/api/x402. The same data set is also exposed to agents through a hosted MCP server (20 read-only tools, v0.7.3) at https://mcp.bykaranteli.com. ## More from PayAI - Documentation: https://docs.payai.network - OpenAPI description: https://payai.network/openapi.json - Facilitator API: https://facilitator.payai.network - Agent guide: https://payai.network/llms.txt - Blog: https://blog.payai.network - GitHub: https://github.com/PayAINetwork - Support: info@payai.network --- # Source: https://payai.network/developers # PayAI Developer Portal Everything needed to charge for a request, pay for one, or find something worth paying for. The API is public, unauthenticated for reads, and described in full at [https://payai.network/openapi.json](https://payai.network/openapi.json). ## Base URL ``` https://facilitator.payai.network ``` Point x402 middleware or an x402 client at that host. There is no separate sandbox: testnet networks are served from the same endpoints, and [the Echo Merchant](https://x402.payai.network) is a live merchant that returns HTTP 402 so you can exercise a real payment for free. ## Endpoints | Method | Path | Operation | What it does | | --- | --- | --- | --- | | GET | `/health` | `getHealth` | Liveness probe | | GET | `/supported` | `getSupportedPaymentKinds` | List supported payment kinds | | GET | `/verify` | `describeVerifyEndpoint` | Describe the verify endpoint | | POST | `/verify` | `verifyPayment` | Verify a signed x402 payment | | GET | `/settle` | `describeSettleEndpoint` | Describe the settle endpoint | | POST | `/settle` | `settlePayment` | Settle a verified x402 payment on-chain | | GET | `/discovery/resources` | `listDiscoveryResources` | List x402-payable resources in the PayAI Bazaar | | GET | `/discovery/stats` | `getDiscoveryStats` | Get aggregate PayAI Bazaar statistics | The full request and response schemas, including every documented failure reason, are in the [OpenAPI 3.1 description](https://payai.network/openapi.json). ## Authentication Read endpoints need none. `POST /verify` and `POST /settle` accept an optional bearer token: ``` Authorization: Bearer ``` The key affects credit accounting, dedicated throughput lanes, and usage analytics — not access. Without one you are served on the free tier. Create a key at [https://merchant.payai.network](https://merchant.payai.network). ## Error model Errors are JSON on every status, including 4xx and 5xx, because a client that has already signed a payment needs to know precisely what happened. - `POST /verify` returns `{ isValid: false, invalidReason, invalidMessage }` - `POST /settle` returns `{ success: false, errorReason, errorMessage, transaction, network, payer }` Branch on `invalidReason` / `errorReason` — these are stable across releases. The message is for humans and carries field-level validation detail. One reason deserves special handling: `settlement_pending` means the settlement outran its response budget and is **still in flight**. It is not a failure. The response carries the broadcast `transaction` hash; re-submit the identical request to poll for the real outcome, and treat `duplicate_settlement` on that poll as "still working". Settlement is idempotent per payment, so retrying cannot double-charge. ## Versioning and deprecation The facilitator is versioned by the x402 protocol version it speaks, not by a URL path segment. Requests carry `x402Version` (1 or 2); both are served from the same endpoints, so you pin a version by what you send. - **x402 v1** uses short network names — `base`, `solana` - **x402 v2** uses CAIP-2 identifiers — `eip155:8453`, `solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp` Call `GET https://facilitator.payai.network/supported` to see which combinations are live. A payment kind is withdrawn from that list before the endpoints stop accepting it, so polling `/supported` gives advance notice of a removal. Breaking changes arrive as a new `x402Version`. ## Rate limits Throughput is limited per client at the edge; exceeding it returns HTTP 429. The facilitator does not currently emit `RateLimit` response headers, so back off on the status code rather than on a header budget. ## Machine-readable surfaces - [OpenAPI 3.1 description](https://payai.network/openapi.json) - [llms.txt](https://payai.network/llms.txt) — when to use PayAI and how to call it - [llms-full.txt](https://payai.network/llms-full.txt) — the whole site as one document - [MCP server](https://payai.network/mcp) — Streamable HTTP, no authentication, searches the PayAI docs corpus. Also at `/.well-known/mcp`. - [MCP manifest](https://payai.network/.well-known/mcp.json) and [AI catalog](https://payai.network/.well-known/ai-catalog.json) - [API catalog (RFC 9727)](https://payai.network/.well-known/api-catalog) Every page on this site also serves Markdown — send `Accept: text/markdown` or append `.md` to the path. ## Quickstarts Accept payments: - [Express](https://docs.payai.network/x402/servers/typescript/express) · [Hono](https://docs.payai.network/x402/servers/typescript/hono) · [Next.js](https://docs.payai.network/x402/servers/typescript/nextjs) - [FastAPI](https://docs.payai.network/x402/servers/python/fastapi) · [Flask](https://docs.payai.network/x402/servers/python/flask) - [Gin](https://docs.payai.network/x402/servers/go/gin) Make payments: - [Axios](https://docs.payai.network/x402/clients/typescript/axios) · [Fetch](https://docs.payai.network/x402/clients/typescript/fetch) - [httpx](https://docs.payai.network/x402/clients/python/httpx) · [requests](https://docs.payai.network/x402/clients/python/requests) - [Go net/http](https://docs.payai.network/x402/clients/go/http) Prefer no SDK? The manual flows spell out the raw HTTP exchange: [TypeScript](https://docs.payai.network/x402/clients/typescript/manual-flow) · [Python](https://docs.payai.network/x402/clients/python/manual-flow). ## Discovery `GET https://facilitator.payai.network/discovery/resources` returns the PayAI Bazaar: every resource currently accepting x402 payments, with the payment terms needed to call it and, where the seller published them, input and output schemas. `GET https://facilitator.payai.network/discovery/stats` returns catalog size, settlement counts, and per-network volume. ## More from PayAI - Documentation: https://docs.payai.network - OpenAPI description: https://payai.network/openapi.json - Facilitator API: https://facilitator.payai.network - Agent guide: https://payai.network/llms.txt - Blog: https://blog.payai.network - GitHub: https://github.com/PayAINetwork - Support: info@payai.network