# API & endpoints Paybox's developer surface is small on purpose: **OAuth 2.1** to authorize, then **MCP** to act. Connecting wallets and credentials, client management, approvals, and audit are done by the user in the Paybox app — they are not a public API. ## Origins | Role | URL | | --- | --- | | API origin (OAuth issuer + MCP) | `https://api.paybox.sh` | | App / consent UI | `https://app.paybox.sh` | The OAuth **issuer** and the MCP **resource** derive from the API origin: the resource is `/mcp`. Always start from discovery rather than hard-coding paths. ## Public endpoints | Endpoint | Method | Auth | Purpose | | --- | --- | --- | --- | | `/.well-known/oauth-authorization-server` | GET | none | OAuth 2.1 server metadata (RFC 8414). | | `/.well-known/oauth-protected-resource` | GET | none | Protected-resource metadata (RFC 9728). | | `/oauth/register` | POST | none | Dynamic client registration (RFC 7591). | | `/oauth/authorize` | GET | user (browser) | Authorization request (code + PKCE S256). | | `/oauth/token` | POST | none (public client) | Exchange code or refresh token for an access token. | | `/mcp` | POST | Bearer access token | The MCP endpoint — all agent operations. | See **[OAuth 2.1](/connect/oauth)** for request/response shapes, scopes, token TTLs, and error codes, and **[MCP tools](/reference/mcp-tools)** for everything an agent can call on `/mcp`. ## Authentication Agents authenticate to `/mcp` with a **bearer access token** obtained via the OAuth flow: ```http POST /mcp Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9… ``` The token is **audience-bound** to the MCP resource and carries the **grant set** the user approved — which credentials, and the approval mode for each. It never overrides a passkey step-up: sensitive operations still pause for the user. See **[Approvals & passkeys](/concepts/approvals)**. A personal **`pbx_live_*` API key** (issued from the app's Clients screen) works as the same bearer — both resolve to the same scoped client. Keys suit headless use (CI, servers) where the OAuth browser flow doesn't; the SDK and CLI accept either. ## Not a public API The first-party Paybox app (web + mobile) uses internal `/api/*` routes for sign-in, vaulting credentials, managing clients, reviewing approvals, and reading the audit log. These are **not part of the developer surface** and are not documented here — an integration never calls them. Everything an external agent needs is the OAuth flow plus the MCP tools above. :::note A typed Node SDK and CLI ship over this surface — `@paybox-sh/sdk`, with in-process (iframe-free) wallet signing. See **[SDK & CLI](/sdk-cli)**. :::