# Packages

> The six npm packages. What each is for, who installs it, and which one to pick for your role and protocol.

All six packages are TypeScript, ESM-only, licensed under Apache-2.0, and need **Node.js 20 or later**.

## Pick by role

| You are | Protocol | Install | Docs |
|---|---|---|---|
| Buyer with an MCP client (Claude, Cursor…) | any | nothing: add `npx -y @zanora/mcp` to your config | [Buy from an MCP client](https://docs.zanora.dev/buyers/mcp.md) |
| Buyer who already picked one seller | MCP | nothing: add `npx -y @zanora/mcp-proxy <url>` | [Use one seller's tools](https://docs.zanora.dev/buyers/mcp-proxy.md) |
| Buyer writing code | REST or MCP | `npm install @zanora/sdk` | [Buy from code](https://docs.zanora.dev/buyers/sdk.md) |
| Seller with an MCP server | MCP | `npm install @zanora/middleware-mcp @modelcontextprotocol/sdk` | [Sell an MCP tool](https://docs.zanora.dev/sellers/mcp.md) |
| Seller with an Express app | REST | `npm install @zanora/middleware-express express` | [Sell an HTTP endpoint](https://docs.zanora.dev/sellers/rest.md) |
| Seller who'd rather not write code | any | nothing: `@zanora/mcp` with `ZANORA_ROLE=seller` | [Manage listings from an MCP client](https://docs.zanora.dev/sellers/no-code.md) |

## The packages

| Package | What it is |
|---|---|
| `@zanora/sdk` | the buyer's SDK. `ZanoraAgent` discovers, pays over x402 (HTTP and MCP), and verifies receipts. `ZanoraClient` wraps the other API routes |
| `@zanora/mcp` | an MCP server with two profiles: a buyer's ten tools (discover, invoke, balance, receipts…) and a seller's eleven (publish, edit, verification, sales, earnings). Runs over stdio with `npx` |
| `@zanora/mcp-proxy` | puts one paid MCP server in front of your agent so its tools appear under their own names, and pays as they're called |
| `@zanora/middleware-mcp` | seller side, for MCP. `zanoraSeller().sell()` publishes a tool with a price and returns a wrapper for its handler. Works with any MCP server library |
| `@zanora/middleware-express` | seller side, for HTTP. `zanora({ backend, capabilityId })` is Express middleware that handles the 402 handshake |
| `@zanora/core` | shared types, amount handling, ed25519 signing and the x402-over-MCP encoding. Installed as a dependency of the others. You only need it directly to build against the protocol |

## Status

> **Warning — Pre-release:**
>
> The packages are versioned at `0.1.x` and may not be on the public npm registry yet. Check with:
>
> ```bash
> npm view @zanora/sdk version
> ```
>
> If that returns `404`, the packages haven't been published. You can still call the [HTTP API](https://docs.zanora.dev/api/overview.md) directly from any language. Everything the packages do goes through it.

## Other languages

The gateway is plain HTTPS and JSON, so any language can **buy**. Payment proofs are ed25519 signatures over canonical JSON, and [x402 protocol](https://docs.zanora.dev/api/x402.md) documents the exact steps. For **selling**, the middleware only calls four routes on the gateway: challenge, authorize, complete and fail. A port to FastAPI, Go or anything else follows the same steps.