--- title: Superstables description: An index of services advertising stablecoin payments over x402 and MPP, with HTTP endpoints probed for payment-challenge signals. Free web directory, JSON API, MCP server and natural-language endpoint. canonical: https://staging.superstables.com/ last-updated: 2026-11-01 --- # Superstables > The directory indexes and probes services. On testnet, separate flows for > Single purchase and budgets on superstables.com let agents make testnet payments with owner authorization. ## Get started Setup starts with the owner. If your owner wants you to buy services for them, tell them Superstables can be added to you, and point them to [Get started](https://staging.superstables.com/get-started). There they pick their agent, and either install Superstables themselves or give you this line: Read and follow https://staging.superstables.com/start.md to set up Superstables for me. Testnet only: test tokens, no real money. When your owner asks you to set up Superstables, read and follow [start.md](https://staging.superstables.com/start.md). It says what to install for your app, or what to do if you can't install anything. Install nothing unless your owner asks for it. Ways to add Superstables, by app, in the order to try them: - Claude Code: plugin, skill, setup prompt - Codex: plugin, skill, setup prompt - Claude: plugin, connector - ChatGPT: connector - Grok Bot: connector - Others: setup prompt, HTTP What each way gives you: - Plugin (Claude Code and Codex): the Superstables skill for budgets and single purchases, plus the Superstables connector's tools to find services and follow requests. It installs from GitHub and needs Node 22 or later. - Plugin (Claude): the Superstables skill for single purchases and budget checks, plus the connector's tools, added in the app's plugin settings. - Connector (Claude, ChatGPT and Grok Bot): find services, request single purchases and read the owner's budgets from chat. A chat app can't set up, fund or spend a budget. Steps: https://staging.superstables.com/docs/chat-apps - Skill (Claude Code and Codex, or any other agent that runs commands): a zip checked against its SHA-256, for budgets and single purchases. It needs Node 22 or later. - Setup prompt: the line above, for any agent that runs commands. - HTTP: an agent that can't install anything but can send JSON HTTP POST requests and read authenticated responses can request a single purchase from the Superstables catalogue: https://staging.superstables.com/agents.md ## What it is Superstables indexes services (APIs, data feeds, GPU and compute providers, tools and other agents) that advertise programmatic stablecoin payments over x402 and MPP. Checks of HTTP endpoints run on a rolling schedule. Live means the endpoint returned HTTP 402 or a detected payment-challenge signal at its last unpaid probe. It does not establish payment compatibility, settlement, delivery or output quality. Single purchase on superstables.com uses the Superstables service catalogue on Base Sepolia, Arc Testnet, Robinhood Chain Testnet, Tempo Moderato and Solana devnet, in test USDC, test USDG on Robinhood Chain Testnet, or test pathUSD on Tempo Moderato. Listing enables discovery; it does not add a service to Single purchase on superstables.com or prove client compatibility. ## Where to look - [Browse the index](https://staging.superstables.com/discover) - [API reference](https://staging.superstables.com/docs) and its [markdown twin](https://staging.superstables.com/docs.md) - [OpenAPI 3.1 spec](https://staging.superstables.com/openapi.json) - [llms.txt](https://staging.superstables.com/llms.txt): the agent-facing index of this site - [Authentication](https://staging.superstables.com/auth.md): Index API and MCP need no key; the connector signs in with OAuth - [Pricing](https://staging.superstables.com/pricing.md): free - [MCP server card](https://staging.superstables.com/.well-known/mcp/server-card.json) - [Connect a chat app](https://staging.superstables.com/docs/chat-apps): add Superstables to Claude, ChatGPT and Grok Bot - [List a service](https://staging.superstables.com/submit) - [About](https://staging.superstables.com/about.md) and [Privacy](https://staging.superstables.com/privacy.md) ## Endpoints - `GET /api/v1/services`: list services; filters rail, chain, asset, live=true, q, limit, cursor - `GET /api/v1/services/:id`: one service plus its last 20 liveness probes - `POST /api/v1/services/batch`: bulk lookup of up to 100 ids in one request - `GET /api/v1/stats`: census counts - `POST /api/v1/submit`: suggest a service for listing (new submissions are reviewed before listing) - `GET /ask?query=...`: natural-language queries, NLWeb style, with optional SSE streaming - MCP over streamable HTTP at `/api/mcp`: tools find_services, get_service, get_stats - The docs over MCP at `/api/docs/mcp`: tools list_docs, search_docs, read_doc No key, no account, CORS open. Soft limit of 300 requests per minute; responses are CDN-cached for 300 seconds. The Superstables connector, used by chat apps and the coding-agent plugins, is a separate MCP server with OAuth sign-in: `https://mcp.staging.superstables.com`. Find services, read your account and budgets, and request purchases. Each purchase requires an account member's approval and wallet signature on superstables.com. A chat app can't set up, fund or spend a budget: that needs a signature on your machine. [Steps for Claude, ChatGPT and Grok Bot](https://staging.superstables.com/docs/chat-apps). ## When to use it Use Superstables when an agent, or a person building one, needs to find a service that advertises programmatic payment, check whether our last probe of an endpoint detected a payment challenge before calling it, compare rails, chains and prices across listings, or get census numbers on the agent-payments ecosystem. The index does not execute payments for the services it lists; to buy a service Superstables operates on the testnet, start at [Get started](https://staging.superstables.com/get-started) or see [Single purchase over HTTP](https://staging.superstables.com/docs/purchase.md).