---
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://superstables-8q80gtkmb-superstables.vercel.app/
last-updated: 2026-10-09
---

# Superstables

> The directory indexes and probes services. In this staging preview, separate flows for
> Single purchase and budgets on superstables.com let agents make testnet payments with owner authorization.

## Get started

- [Get started](https://superstables-8q80gtkmb-superstables.vercel.app/get-started): one prompt an owner gives their agent to set up Superstables. Testnet only.
- [start.md](https://superstables-8q80gtkmb-superstables.vercel.app/start.md): instructions for checking the skill zip's SHA-256 and installing it, buying through HTTP POST requests, or explaining why an agent that can only read pages cannot complete setup.
- [Superstables for agents](https://superstables-8q80gtkmb-superstables.vercel.app/agents.md): what an agent can do here, and how
- [Buy a service over HTTP](https://superstables-8q80gtkmb-superstables.vercel.app/docs/purchase.md): an agent buys a Superstables test service, and the owner approves the payment with their own wallet

## 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://superstables-8q80gtkmb-superstables.vercel.app/discover)
- [API reference](https://superstables-8q80gtkmb-superstables.vercel.app/docs) and its [markdown twin](https://superstables-8q80gtkmb-superstables.vercel.app/docs.md)
- [OpenAPI 3.1 spec](https://superstables-8q80gtkmb-superstables.vercel.app/openapi.json)
- [llms.txt](https://superstables-8q80gtkmb-superstables.vercel.app/llms.txt): the agent-facing index of this site
- [Authentication](https://superstables-8q80gtkmb-superstables.vercel.app/auth.md): none required
- [Pricing](https://superstables-8q80gtkmb-superstables.vercel.app/pricing.md): free
- [MCP server card](https://superstables-8q80gtkmb-superstables.vercel.app/.well-known/mcp/server-card.json)
- [List a service](https://superstables-8q80gtkmb-superstables.vercel.app/submit)
- [About](https://superstables-8q80gtkmb-superstables.vercel.app/about.md) and [Privacy](https://superstables-8q80gtkmb-superstables.vercel.app/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.

## 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://superstables-8q80gtkmb-superstables.vercel.app/get-started)
or see [Buy a service over HTTP](https://superstables-8q80gtkmb-superstables.vercel.app/docs/purchase.md).