# StellarX402

## Docs

- [introduction](https://docs.madra.finance/introduction.md): StellarX402 enables per-request HTTP payments on Stellar using the x402 protocol. Monetize any API endpoint without accounts, billing systems, or API keys.
- [Quickstart for Buyers & Agents](https://docs.madra.finance/getting-started/quickstart-buyers.md): Search the Bazaar, pay for a resource, and handle rejections from your own code in under ten minutes.
- [Quickstart for Sellers](https://docs.madra.finance/getting-started/quickstart-sellers.md): Put a price on an existing HTTP endpoint, confirm it was cataloged in the Bazaar, and watch it get paid.
- [Quickstart for Operators](https://docs.madra.finance/getting-started/quickstart-operators.md): Stand up your own StellarX402 facilitator, fund the sponsor account, and process a real paid request end-to-end.
- [HTTP 402 Payment Required](https://docs.madra.finance/concepts/http-402.md): How the reserved 402 status code is used as a machine-readable payment challenge in x402.
- [Client, Facilitator, Server](https://docs.madra.finance/concepts/client-facilitator-server.md): The three parties in every x402 payment and what each one is (and is not) responsible for.
- [The Facilitator](https://docs.madra.finance/concepts/facilitator.md): What StellarX402's facilitator does under the hood, and where its responsibilities end.
- [The Bazaar (Discovery Layer)](https://docs.madra.finance/concepts/bazaar.md): What the Bazaar is as a concept before you touch a discovery endpoint.
- [Networks & Token Support](https://docs.madra.finance/concepts/networks-and-tokens.md): Which Stellar networks and SEP-41 tokens StellarX402 supports, and how amounts are formatted.
- [Payment Schemes Overview](https://docs.madra.finance/payment-schemes/overview.md): The schemes StellarX402 supports today, when to use each, and how they slot into the verify/settle cycle.
- [Exact Scheme](https://docs.madra.finance/payment-schemes/exact.md): Fixed-price payments where the client authorizes exactly what the seller will charge.
- [Upto Scheme](https://docs.madra.finance/payment-schemes/upto.md): Metered payments where the client authorizes a ceiling and the seller settles for the actual amount used.
- [Batch Settlement (Planned)](https://docs.madra.finance/payment-schemes/batch-settlement.md): A planned scheme for high-frequency callers where per-call amounts are too small to settle on-chain individually.
- [Discovery Overview](https://docs.madra.finance/discovery/overview.md): How the Bazaar catalogs paid endpoints and MCP tools, and the pieces that make search work.
- [Automatic Cataloging](https://docs.madra.finance/discovery/automatic-cataloging.md): How endpoints and MCP tools end up in the Bazaar without a manual registration step.
- [Search & Ranking](https://docs.madra.finance/discovery/search-and-ranking.md): How the Bazaar ranks results, and how to reason about why a listing appears where it does.
- [Discovery Filters](https://docs.madra.finance/discovery/filters.md): Structured filters supported on /discovery/resources and /discovery/search.
- [Cataloging MCP Tools](https://docs.madra.finance/discovery/cataloging-mcp-tools.md): How MCP tools get indexed in the Bazaar alongside HTTP endpoints, and what agents see when they discover them.
- [Route Template & Catalog Integrity](https://docs.madra.finance/discovery/route-template-and-integrity.md): How the Bazaar keeps dynamic routes uniquely addressable and prevents catalog spam.
- [Searching the Bazaar](https://docs.madra.finance/guides/buyers/searching-the-bazaar.md): Query the Bazaar from client code, apply filters, paginate, and interpret ranking.
- [Handling Rejections & Error Codes](https://docs.madra.finance/guides/buyers/handling-rejections.md): How an agent should react to each machine-readable payment rejection so failures do not loop.
- [Budgets & the Upto Scheme](https://docs.madra.finance/guides/buyers/budgets-and-upto.md): Cap what an agent can spend per call, per tool, and per session using upto ceilings and smart account contracts.
- [MCP Integration for Agents](https://docs.madra.finance/guides/buyers/mcp-integration.md): Wire the Bazaar and StellarX402 client into an MCP-speaking agent runtime.
- [Declaring Discovery Metadata](https://docs.madra.finance/guides/sellers/declaring-discovery-metadata.md): What to put in the describe block so agents can find your endpoint and know how to call it.
- [Choosing a Pricing Scheme](https://docs.madra.finance/guides/sellers/choosing-a-pricing-scheme.md): How to decide between the exact and upto schemes for your endpoint.
- [Verifying Your Listing](https://docs.madra.finance/guides/sellers/verifying-your-listing.md): Confirm your endpoint is in the Bazaar and diagnose why it might not be ranking as expected.
- [Going to Mainnet](https://docs.madra.finance/guides/sellers/going-to-mainnet.md): The checklist before flipping your endpoint from Stellar Testnet to Mainnet.
- [Configuration Reference](https://docs.madra.finance/guides/operators/configuration-reference.md): Every environment variable and config key StellarX402 accepts, grouped by subsystem.
- [Deploying to Mainnet](https://docs.madra.finance/guides/operators/deploying-to-mainnet.md): Sponsor funding math, RPC selection, and the cutover checklist for taking a facilitator to production.
- [Observability](https://docs.madra.finance/guides/operators/observability.md): Metrics, tracing, and dashboards for a StellarX402 facilitator, and what every number on them means.
- [Security Hardening](https://docs.madra.finance/guides/operators/security-hardening.md): Turn a running facilitator into a production-safe deployment: keys, admin surface, rate limits, and origin controls.
- [Fee Configuration](https://docs.madra.finance/guides/operators/fee-configuration.md): Sponsor account setup, fee ceilings, and the trade-offs behind each knob.
- [Runbook](https://docs.madra.finance/guides/operators/runbook.md): Incident response for the situations that actually happen at 3am when running a StellarX402 facilitator.
- [Lifecycle Hooks](https://docs.madra.finance/advanced/lifecycle-hooks.md): Hook into the verify and settle lifecycle to add logging, custom validation, or side effects.
- [Wallet Compatibility](https://docs.madra.finance/advanced/wallet-compatibility.md): Which Stellar wallets support x402 today, what interface they need to expose, and how the client SDK detects them.
- [Self-Facilitation](https://docs.madra.finance/advanced/self-facilitation.md): The rare case where a seller acts as its own facilitator, and why you almost certainly should not do it.
- [GET /discovery/resources](https://docs.madra.finance/api/discovery-resources.md): Structured filter across the Bazaar catalog. Use for listing and faceted queries.
- [GET /discovery/search](https://docs.madra.finance/api/discovery-search.md): Ranked free-text search across the Bazaar catalog. Combines textual relevance with price and activity signals.
- [MCP Tool Schemas](https://docs.madra.finance/api/mcp-tool-schemas.md): The shape of MCP tool listings in the Bazaar and how they are published and consumed.
- [Error & Rejection Codes](https://docs.madra.finance/reference/error-codes.md): Every machine-readable rejection reason StellarX402 can return, in one place.
- [Supported Networks](https://docs.madra.finance/reference/supported-networks.md): Stellar networks StellarX402 supports and their canonical identifiers.
- [Supported Assets](https://docs.madra.finance/reference/supported-assets.md): SEP-41 assets StellarX402 can settle in, with contract addresses and decimals.
- [Changelog](https://docs.madra.finance/reference/changelog.md): Notable changes to the StellarX402 facilitator, SDKs, and the Bazaar.
- [SDKs](https://docs.madra.finance/developer-tools/sdks.md): Official StellarX402 SDKs for clients, servers, and facilitators.
- [Example Integrations](https://docs.madra.finance/developer-tools/example-integrations.md): Runnable examples showing StellarX402 in real integration shapes.
- [Third-Party Extensions](https://docs.madra.finance/developer-tools/third-party-extensions.md): Community-maintained libraries and integrations for StellarX402.