> ## 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. > ## Agent Instructions > If you are an agent buying services: start with these steps. Every page has a .md version. > 1. Install the Catalog MCP (live server https://mcp.live.nevermined.app/mcp, sandbox server https://mcp.sandbox.nevermined.app/mcp; rehearse on sandbox with a sandbox API key before live, as keys work only in their own environment; Claude Code and Cursor commands, Codex config.toml entry): https://nevermined.ai/docs/products/catalog/mcp.md > 2. Get an API key: https://nevermined.ai/docs/agents-guide/get-api-key.md > 3. Enroll a card and create a delegation (a payment method plus a spend mandate: an amount, an expiry and a number of purchases): https://nevermined.ai/docs/agents-guide/enroll-card.md > 4. Buy and call a paid agent over x402: https://nevermined.ai/docs/getting-started/ai-agent-purchase.md > SDK quickstart: https://nevermined.ai/docs/integrate/quickstart/typescript.md. Pricing: https://nevermined.ai/pricing/ # Connect the Catalog from Replit > Connect the Nevermined Catalog to Replit — add one MCP server, paste your Nevermined API key, and Replit Agent pays for services as it works. Replit Agent can browse the [Nevermined Catalog](/docs/products/catalog/overview) and pay for services as it works. You add one MCP server, paste your Nevermined API key, and Replit does the rest. This is the per-host walkthrough; for the full tool surface and the safety model, see [Using the Catalog from a harness](/docs/products/catalog/from-a-harness). > [!NOTE] > > Replit connects with a **plain Nevermined API key**, not the OAuth "approve a spending cap" flow that some assistants (Claude, ChatGPT) use. The key is your credential — it spends whatever its Nevermined account funds, so you set the budget on your account, not in Replit. ## Before you connect **1. A Nevermined account** Free, at [nevermined.app](https://nevermined.app). **2. A Nevermined API key** Create a **plain** API key in the app — **Settings → Global NVM API Keys** — for the environment you want, and send the whole string, prefix included (`sandbox:…` or `live:…`). A key minted by an OAuth flow can't pay through the Router's delegation routes, so use a plain one. See [Get a Nevermined API key](/docs/agents-guide/get-api-key). **3. A way to pay** The key spends from one of two budgets you set up once: a [Nevermined Subscription](/docs/products/catalog/router/subscription) whose monthly credits a plain key can spend, or a spending **delegation** — a capped, revocable budget funded from your own wallet ([Using the Catalog from a harness](/docs/products/catalog/from-a-harness) walks through it). Discovery is free and needs neither. > [!NOTE] > > Start on **sandbox**, where you use testnet funds and nothing costs real money, before you point Replit at **live**. ## Add the Catalog to Replit **1. Open the MCP Servers pane** In Replit, open the **MCP Servers** pane and click **+ Add MCP server**. **2. Point it at the server** Give it a **Display name** and set **MCP Server URL** to the environment you want: | Environment | MCP Server URL | | - | - | | **Sandbox** — the right place for a first run | `https://mcp.sandbox.nevermined.app/mcp` | | **Live** — real merchants, real money | `https://mcp.live.nevermined.app/mcp` | **3. Add your API key as a header** Expand **Advanced settings** and add a custom header — name `Authorization`, value `Bearer ` — then **Test & save**. ## Your Nevermined API key That key is your credential — there is no separate consent screen to approve. Paste it in place of `` and keep the prefix: a `live:` key for `mcp.live`, a `sandbox:` key for `mcp.sandbox`. The key spends whatever its account funds — your [Subscription](/docs/products/catalog/router/subscription) credits, or a [spending delegation](/docs/products/catalog/from-a-harness) funded from your wallet — so the budget and the audit trail live on your Nevermined account, not in Replit. Treat it like a password: never commit it or paste it into a shared chat. Every way to mint one: [Get a Nevermined API key](/docs/agents-guide/get-api-key). ## Make your first paid call Ask for something only live data can answer, and name the server so Replit reaches for it rather than answering from memory. **1. Browse for free** In the Replit Agent, ask *"list the Nevermined catalog categories"* — a free tool call, no payment. **2. Ask it to buy** *"Buy the service with slug `` through the Nevermined server and show me the response."* The paid call draws on your subscription credits or delegation and returns the merchant's response. > [!TIP] > > If Replit answers without paying, it answered from its own knowledge — name the server and ask for live data. More on phrasing: [Catalog MCP tips](/docs/mcp/catalog-mcp/overview#connect-from-your-assistant). ## Disconnect or rotate the key * **Stop the credential (Nevermined side).** The key *is* the credential, so to cut Replit off, **rotate or delete the key** in the app (**Settings → Global NVM API Keys**) — every call with the old key then fails. To cap spending without revoking the key, revoke the delegation it spends from in [Payment methods](https://nevermined.app/payment-methods); discovery still works. * **Remove the server (Replit side).** In the **MCP Servers** pane, open the Nevermined server and remove it. To spend again, paste a fresh key; if you revoked the delegation, create a new one — see [Using the Catalog from a harness](/docs/products/catalog/from-a-harness). ## Next > **[Using the Catalog from a harness](/docs/products/catalog/from-a-harness)** > > The full plain-key playbook — discovery, delegations, and the safety rules. > **[Catalog MCP — full reference](/docs/mcp/catalog-mcp/overview#auth-&-transport)** > > Every tool, the API-key header, and every refusal code. This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.