Composio

Composio solves the boring half of agent building. An agent that can write a good Slack message is useless until something holds the OAuth token, refreshes it, scopes it to the right end user, and presents Slack's API as a tool the model can actually pick out of a list. Composio is that layer, across more than 1,500 applications.

The managed auth piece handles OAuth flows, API keys and token lifecycles for each connected account, including delegated auth where your end users — not you — own the credentials. The tool router is the answer to the problem every large tool catalogue hits: 1,500 integrations is tens of thousands of actions, far more than fits in a context window, so the router narrows the set to the actions plausibly relevant to the request before the model sees them. A sandboxed runtime gives multi-step tasks an isolated place to execute, and triggers close the loop in the other direction, letting an external event in Gmail, GitHub or Stripe wake an agent rather than the agent polling.

There are two front doors. Composio For You is the no-code route: connect Claude, ChatGPT, Cursor, Codex, OpenClaw, Hermes or any MCP-speaking client to the apps you already use, with a managed MCP gateway exposing one endpoint instead of a dozen server configs. The developer platform is the SDK route — tool execution and auth infrastructure to embed in your own agent — plus a CLI that adds tools and auth to a coding agent in a single command. Enterprise adds SSO, SCIM, customer-managed keys, governance and audit controls, white-labelling and custom SLAs.

The free plan is unusually large: 100,000 tool calls and 50,000 triggers a month, three team members and unlimited connected accounts, with no card. Scale is $29/month including $29 of usage credit and unlimited seats, with overage at $0.0003 per tool call and $0.003 per trigger event; Enterprise is quoted against committed volume. Composio is SOC 2 Type II compliant, encrypts credentials in transit and at rest, and says it serves over 100 million actions a week. It is the pragmatic choice when the agent you are building has to touch a long tail of business software that you do not want to integrate one API at a time.