One API key for many data APIs, without separate sign-ups

Yes, one API key can pay per use for many data APIs: a pay-per-call gateway holds the provider accounts, so your agent signs up once, funds one balance and pays only for calls that ran, instead of ten sign-ups and ten bills. There are three ways to get there. A marketplace gives you one key but still has you subscribe to each API. An auth layer stores your keys and OAuth tokens for you. A gateway holds the accounts itself.

Which one fits depends on whose accounts the data comes from. Auth layers such as Nango or Composio connect your users' own accounts; a data gateway buys the data for you. This post sorts the three, names a product for each with prices read from its own page on 2026-10-13, and says when each is the wrong choice. looot is a gateway, and looot publishes this post, so read its sections with that in mind.

My agent needs data from 10 APIs: how do I avoid 10 sign-ups?

Put a gateway in front of them, so the agent signs in once and the gateway holds the ten vendor accounts. The sign-ups pile up because each data job has several vendors, and each vendor wants its own account. An agent that finds emails, enriches companies, reads search results and scrapes pages touches at least four vendors. That means four sign-ups, four keys in an environment file, four billing pages and four ways a free tier can run out.

The keys are the visible cost. The hidden one is that each vendor returns a different shape, rate limits differently and bills differently. An agent that must handle all of that spends its context on plumbing.

Option 1: a marketplace with one key

RapidAPI is the known example. Its FAQ, read on 2026-10-13, says one account and API key reach thousands of APIs. You still pick a plan per API, and the pricing docs describe recurring plans with a quota and overage fees past it.

Use it when the API you want is niche and only listed there. Skip it when you want one bill for a dozen routine lookups, because a dozen plans is still a dozen quotas. RapidAPI alternatives for AI agents goes through the others.

Option 2: an auth layer that stores credentials

Composio and Nango manage authentication, not data. You connect your users' accounts once, and the layer stores and refreshes the tokens.

• Composio lists a free tier of 100K tool calls a month and Pro at $29 a month, with $0.0003 per call past the included amount (composio.dev/pricing, read 2026-10-13). It acts inside apps your user has connected, such as Gmail or Slack.
• Nango lists a free tier with 10 connections, and pay-as-you-go at $50 a month with $0.29 per connection (nango.dev/pricing, read 2026-10-13). Its page says it serves your own users' OAuth integrations.

Use one when the data lives in your user's own accounts. They are the right tool there, and a gateway is not. Skip them when you only want public data, since the auth layer does not supply the data, only the access.

Option 3: a pay-per-call gateway

A gateway holds the provider accounts. You sign in once, top up a balance, and call endpoints from one catalog. looot has a $5 minimum top-up (skill file) and no subscription. The catalog is free to search, and the price is quoted before every run. See pricing for how the fee is shown.

On looot's keys the price includes a fee that the quote discloses. On your own provider key there is no markup. That choice matters if you already pay a vendor for a plan: you can attach your own key and still use the same interface.

The limits: the catalog is only the providers looot has onboarded. It cannot act inside your user's Gmail. And scheduled runs are not available yet, so a recurring job needs you to start it.

How do the three compare?

How do I choose?

Ask whose account holds the data.

1. If it is your user's account, use an auth layer.
2. If it is a public or licensed dataset from a niche vendor, use a marketplace.
3. If it is a routine lookup that many vendors can answer, use a gateway and let the cheapest or most reliable provider run first.

You can mix them. A product that sends from a user's inbox and enriches the recipient uses Composio for the first and a gateway for the second.

Try it: price three jobs before you spend

Every step in that prompt is free.

What this post does not cover

We did not run Composio, Nango or RapidAPI for this post. We read their pages and docs on 2026-10-13. Prices change, so open the cited page before you buy. looot prices come from the live catalog, last checked 2026-10-13.

For the connection side, see MCP gateway for agents and the setup page.

Author: the looot team.