> ## Documentation Index
> Fetch the complete documentation index at: https://nevermined.ai/docs/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](/docs/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.

<Note>
  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](/docs/products/x402-facilitator/overview)**. You can be on both sides at once, and you can even **[add your own AI service](/docs/products/catalog/ai-services#add-your-ai-service)** to the Catalog so other buyers discover it.
</Note>

## 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](/docs/products/catalog/ai-services) for the full offering and how to add your own, or [Discovering services](/docs/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:

```mermaid theme={null}
flowchart LR
    Agent["Your agent"]
    Catalog["Nevermined Catalog<br/>discover services"]
    Router["Nevermined Router<br/>one budget, one API key"]
    S1["AI Service A · x402"]
    S2["AI Service B · MPP"]
    S3["AI Service C · x402"]

    Agent -->|"1 · browse and pick"| Catalog
    Agent -->|"2 · route the payment"| Router
    Router --> S1
    Router --> S2
    Router --> S3
```

The services on the right 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.

<CardGroup cols={2}>
  <Card title="The Catalog: discover" icon="magnifying-glass" href="/docs/products/catalog/discover">
    Browse or query the directory to find a service that does what your agent needs, and read its price, protocol, and endpoints.
  </Card>

  <Card title="The Router: pay" icon="route" href="/docs/products/catalog/router/overview">
    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.
  </Card>
</CardGroup>

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

<Steps>
  <Step title="A Nevermined API key">
    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](/docs/products/catalog/router/quickstart#1-get-an-api-key).
  </Step>

  <Step title="A Delegation">
    Your budget: a hard cap in cents and an expiry. Created once, reused for every payment until it's exhausted or expires.
  </Step>

  <Step title="A funded wallet">
    Both rails **pull** from your own custodial wallet, so it must already hold the payment asset on the network you're paying on.
  </Step>
</Steps>

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

<CardGroup cols={3}>
  <Card title="Natural language" icon="comment" href="/docs/development-guide/build-using-nvm-skill">
    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.
  </Card>

  <Card title="MCP" icon="plug" href="/docs/development-guide/build-using-nvm-mcp">
    Wire Nevermined into any MCP-capable client so the Catalog and Router become tools your agent can call directly.
  </Card>

  <Card title="Plain HTTP" icon="code" href="/docs/products/catalog/router/quickstart">
    Everything is public REST. Any agent, in any language, can query the Catalog and route a paid call with `curl` or `fetch`.
  </Card>
</CardGroup>

## Environments

| Environment | API base                             | Purpose                 |
| ----------- | ------------------------------------ | ----------------------- |
| **Sandbox** | `https://api.sandbox.nevermined.app` | Development and testing |
| **Live**    | `https://api.live.nevermined.app`    | Real payments           |

<Warning>
  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.
</Warning>

## Next

<CardGroup cols={2}>
  <Card title="Discovering services" icon="magnifying-glass" href="/docs/products/catalog/discover">
    Browse the app, query the read API, and understand what "listed" means.
  </Card>

  <Card title="Router quickstart" icon="rocket" href="/docs/products/catalog/router/quickstart">
    From an API key to a paid call, in five steps.
  </Card>

  <Card title="How the Router works" icon="diagram-project" href="/docs/products/catalog/router/how-it-works">
    The payment flow, the two call modes, and where custody sits.
  </Card>

  <Card title="Guardrails" icon="shield-check" href="/docs/products/catalog/router/guardrails">
    What the Router enforces, what it refuses, and every error code it can return.
  </Card>
</CardGroup>


## Related topics

- [Router Overview](/docs/products/catalog/router/overview.md)
- [Overview](/docs/getting-started/overview.md)
- [API error codes](/docs/development-guide/api-errors/codes.md)
- [Payment ledger](/docs/products/catalog/router/ledger.md)
- [Pre-requisites](/docs/api-reference/introduction.md)