> ## Documentation Index > Fetch the complete documentation index at: https://developers.fireblocks.com/llms.txt > Use this file to discover all available pages before exploring further. # Get Started with x402 on Fireblocks > New to x402? Understand what it is, decide whether you're selling, buying, or both, and choose between the hosted and open-source Fireblocks facilitator. x402 lets software pay for an HTTP request the moment it makes it, with no account, subscription, or card on file. A server answers a request with `402 Payment Required` and a price; the caller signs a one-time authorization to pay exactly that amount in a stablecoin such as USDC; the server verifies and delivers. It is built for machine-to-machine and agent-to-service commerce: API monetization, pay-per-call data, agentic checkout, and content metering. This page orients you and points you to the right starting path. For the protocol mechanics and the terms used throughout these docs, see [x402 Concepts and Glossary](/docs/x402-concepts). Fireblocks gives you both halves of an x402 deployment, with private keys held in Fireblocks rather than in your application: * A **facilitator** that verifies signatures and settles payments on-chain. * An **agent** that pays for x402-protected resources from a Fireblocks vault. ## Are you selling, buying, or both? Your first decision is which side of an x402 payment you are on. Most teams start with one and add the other later. | You want to… | You are the… | Start here | | ------------------------------------------------ | -------------------------------------- | ------------------------------------------------------------------------------------------ | | Charge for an API, dataset, or endpoint | Seller (resource server + facilitator) | [Facilitator Overview](/docs/x402-facilitator-overview) | | Let an AI agent pay for resources autonomously | Buyer (agent) | [x402 Agent](/docs/x402-agent) | | Run a marketplace where agents pay your services | Both | [Facilitator Overview](/docs/x402-facilitator-overview) and [x402 Agent](/docs/x402-agent) | ### Selling: run a facilitator The facilitator is the service your merchant server calls to verify a payment signature and settle the transfer on-chain through your Fireblocks vault. Your server keeps serving its own traffic and returns the `402` itself; customer traffic never passes through the facilitator. Once you are running, you declare the things you sell as products and, optionally, publish them so agents can discover them. * [Facilitator Overview](/docs/x402-facilitator-overview) — what the facilitator does and a clone-to-running quick start. * [Integration](/docs/x402-facilitator-integration) — wire the facilitator into your merchant server. * [Build an Agentic Product Catalog](/docs/x402-facilitator-product-catalog) — declare, price, and publish what you sell. * [Operating and Production](/docs/x402-facilitator-operations) — config, auth, the management API, and production deployment. ### Buying: run an agent The x402 Agent gives any autonomous agent the ability to pay for `402`-protected resources using a Fireblocks vault. It detects the `402`, signs the payment authorization through Fireblocks, and retries the request. It ships as an MCP server (for Claude Desktop, Cursor, and other MCP clients) and a CLI. * [x402 Agent](/docs/x402-agent) — the agent library, its MCP server and CLI, and secure deployment. * [Fund and Control Agent Spending](/docs/x402-agent-spending-controls) — fund agents and bound what they spend at company scale. ## Hosted or open-source facilitator? If you are selling, you choose how the facilitator runs: | | Open-source (self-hosted) | Hosted (managed) | | ---------- | --------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------- | | You run | The Node.js facilitator from [github.com/fireblocks/x402-facilitator](https://github.com/fireblocks/x402-facilitator) | Nothing — Fireblocks operates a managed endpoint | | You manage | Deployment, upgrades, monitoring, the payment store | Configuration only | | Best for | Full control, custom pricing or mechanisms, on-prem requirements | Production speed with no infrastructure to run | | Get it | Clone and follow the [Overview](/docs/x402-facilitator-overview) | [Talk to us about early access](https://www.fireblocks.com/#request-demo) | These docs describe the open-source facilitator you run yourself. The hosted facilitator exposes the same payment model. ## Your path to a first payment If you are evaluating x402 hands-on, this is the fastest route from nothing to a settled payment on a testnet: 1. **Learn the vocabulary.** Skim [x402 Concepts and Glossary](/docs/x402-concepts) so the rest of the docs read clearly. 2. **Set up prerequisites.** Create a Fireblocks workspace, an API user, and a vault, and get testnet USDC and gas. See [Prerequisites and Testnet Funds](/docs/x402-prerequisites). 3. **Run the quickstart.** Wire the example merchant, facilitator, and test client into one settled payment. See [x402 Quickstart](/docs/x402-quickstart). 4. **Go deeper** on the side you care about: [Integration](/docs/x402-facilitator-integration) for selling, or [Fund and Control Agent Spending](/docs/x402-agent-spending-controls) for buying. x402 is testnet-only by default on the Fireblocks facilitator. It refuses to register mainnet assets or boot with them unless you explicitly opt in. Evaluate on a testnet first, then read [Operating and Production](/docs/x402-facilitator-operations#network-policy) before enabling mainnet. ## What to read next * [x402 Concepts and Glossary](/docs/x402-concepts) — every term used across these docs. * [Prerequisites and Testnet Funds](/docs/x402-prerequisites) — what you need before you start, and how to get testnet money. * [x402 Quickstart](/docs/x402-quickstart) — your first settled payment, end to end. * [Supported Networks and Assets](/docs/x402-networks-assets) — which chains and tokens work, and on which networks.