> ## Documentation Index
> Fetch the complete documentation index at: https://neverminedag-video-documentation.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.
# Catalog Overview
> A curated directory of external AI services your agents can discover and pay for — through one budget, over the Nevermined Router.
The **Nevermined Catalog** is a curated directory of external AI services your agents can pay for — browsable by a human at [nevermined.app/catalog](https://nevermined.app/catalog/), and readable by an agent over a public API. Every listed service prices each request on the wire, so your agent can **find** a capability it needs and **pay** for it in the same motion, without a signup, an API key, or a subscription at the provider.
The Catalog is the front door; the **[Router](/products/catalog/router/overview)** is how you walk through it. You discover a service in the Catalog, then pay it through the Router from a budget you control. The two are one product read in one direction: **spending** at services that were never onboarded to Nevermined.
The Catalog lists services you **buy from**. If instead you want your own API to *get paid* by callers, that's the seller side — see the **[x402 Facilitator](/products/x402-facilitator/overview)**. You can be on both sides at once, and you can even **[add your own AI service](/products/catalog/ai-services#add-your-ai-service)** to the Catalog so other buyers discover it.
## What's in it
Every listing is an external service that charges **per request**, on one of two payment rails the Router can settle:
| Protocol | What it is | Router-payable |
| -------- | --------------------------------------------------------------------------- | -------------- |
| **x402** | The service answers `HTTP 402` advertising an `accepts` array | ✅ Listed |
| **MPP** | The service answers `HTTP 402` with a `WWW-Authenticate: Payment` challenge | ✅ Listed |
Services that authenticate with a long-lived API key and bill you monthly aren't in the listed set — there's no per-call price on the wire for the Router to pay. The Catalog only surfaces what an autonomous agent can actually buy.
Listings are organized into a curated set of categories — **Data & Enrichment**, **Search & Research**, **Crypto & Blockchain**, **Finance & Markets**, **AI & Media**, **Web Scraping & Automation**, and more — each with granular sub-categories. See [AI Services](/products/catalog/ai-services) for the full offering and how to add your own, or [Discovering services](/products/catalog/discover) for browsing and filtering.
## How the Catalog and Router fit together
One agent, one budget, one API key — reaching many independent services it never had to sign up for. Those services are unrelated to each other and to Nevermined: different providers, different payment rails, no shared account. Your agent treats them uniformly because the Router, not the agent, speaks each rail.
Browse or query the directory to find a service that does what your agent needs, and read its price, protocol, and endpoints.
Hand the Router the call you want made. It reads the merchant's payment challenge, pays from your custodial wallet, enforces your budget cap, and relays the answer.
Your agent authenticates with its Nevermined API key and spends against a **Delegation** — a budget with a hard cap and an expiry. It never holds a private key, never learns a payment protocol, and never needs an account with the service it just paid.
## What you need to buy through it
Created from the [Nevermined app](https://nevermined.app). It authenticates you to Nevermined — never send it to a merchant. It must be a current-generation key; see [the Router quickstart](/products/catalog/router/quickstart#1-get-an-api-key).
Your budget: a hard cap in cents and an expiry. Created once, reused for every payment until it's exhausted or expires.
Both rails **pull** from your own custodial wallet, so it must already hold the payment asset on the network you're paying on.
Discovery itself needs none of this — the Catalog read API is public and unauthenticated. You only need a key, a Delegation, and funds at the moment you pay.
## Three ways to use it
Install the AI coding skill and just ask your assistant — "find a weather API and get me tomorrow's forecast for Berlin." It discovers, funds, pays, and returns the answer.
Wire Nevermined into any MCP-capable client so the Catalog and Router become tools your agent can call directly.
Everything is public REST. Any agent, in any language, can query the Catalog and route a paid call with `curl` or `fetch`.
## Environments
| Environment | API base | Purpose |
| ----------- | ------------------------------------ | ----------------------- |
| **Sandbox** | `https://api.sandbox.nevermined.app` | Development and testing |
| **Live** | `https://api.live.nevermined.app` | Real payments |
Both rails settle **real value on public networks**. A call made against the live environment moves real funds to a real merchant. Start in sandbox, and keep your first Delegation cap small.
## Next
Browse the app, query the read API, and understand what "listed" means.
From an API key to a paid call, in five steps.
The payment flow, the two call modes, and where custody sits.
What the Router enforces, what it refuses, and every error code it can return.