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Claude at claude.ai can browse the Nevermined Catalog and pay for services as it works, without you handing over an API key. You add one connector, approve a single spending cap, and Claude does the rest. This is the per-host walkthrough; for the concept and the other assistants, see Using the Catalog from your web assistant.

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See it in action

Connect the Catalog from claude.ai.

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Before you connect

1

A Nevermined account

Free, at nevermined.app. You never share an API key with Claude — the consent cap is the credential.
2

A funded wallet

A paid call draws on a spending cap you approve during connect — a commerce grant: a capped, revocable budget funded from your own wallet, not a key. Fund that wallet first with the asset the service settles in — see Fund your wallet. You approve the cap itself in Approve the spending cap.
Start on sandbox, where you use testnet funds and nothing costs real money, before you point Claude at live.

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Add the Catalog to Claude

1

Open the connector settings

Settings → Connectors → Add custom connector.
2

Paste the server URL

Give the connector a name and paste the URL for the environment you want:Leave the OAuth client ID and secret empty. Claude identifies itself to Nevermined with its own client metadata document, so there is nothing to register.

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Approve the spending cap

Claude opens Nevermined’s consent page at the first paid call — not when you add the connector. It is the one place a human is required.
1

Trigger the consent

Enable the connector in a chat and ask Claude to buy a service (see the next section). The paid call returns 401 and Claude shows an inline Connect card. Click Connect — the consent page opens in a popup.
2

Check who and where

The page shows the Sandbox / Live badge and that claude.ai is asking. On live, the cap is real money.
3

Set the cap and validity

Set the spending cap (USDC or EURC) and how long the grant is valid for, then Grant access. Claude reports Authentication complete and retries the same call with the grant.
That approval is a commerce grant: it spends only from the budget you just approved, only through the Router, and you can revoke it any time. Nevermined’s routing fee comes out of the same cap, and the grant can also read your payment history and wallet balance — the cap bounds what it can spend, not what it can see.

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Make your first paid call

Ask for something only live data can answer, and name the connector so Claude reaches for it rather than answering from memory.
1

Browse for free

Enable the connector from the tools menu and ask “list the Nevermined catalog categories”. It answers with no sign-in.
2

Ask it to buy

“Buy the service with slug <slug> through the Nevermined connector and show me the merchant’s response.” The paid call returns 401, Claude shows the Connect card, and once you approve the cap it retries and returns the result — with the price, the fee and the merchant’s response.
If Claude answers without paying, it answered from its own knowledge — name the connector and ask for live data. Confirm the connection by asking for the Catalog categories, which is a free call that either works or doesn’t. More on phrasing: Catalog MCP tips.

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Disconnect

  • Revoke the budget (Nevermined side). Open Connections and disconnect Claude. The credential stops working on its next call; discovery still works.
  • Remove the connector (Claude side). In Settings → Connectors, open the connector and remove it. You can re-add it later with the same URL.
To spend again — after you disconnect, or after a cap is used up — re-run the connect step and approve a new cap. A budget is never widened or extended in place.

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Next

Using the Catalog from your web assistant

The concept and the other assistants.

Catalog MCP — full reference

Every click path, the consent details, and every refusal code.