Built for AI agents & AI-native apps

Every tool your agent needs. One key. One gateway.

Callio is the API gateway for teams shipping AI agents and AI-native products. One key, MCP-native install, and 143 APIs your agent can call in production from day one.

143

APIs in catalog

One key

for everything

MCP-native

Cursor, Claude

Sandbox + prod

built in

Ship 10x faster

no plumbing

Plugs into

Claude

Cursor

Antigravity

agent.ts

const API_KEY = "paste_key"; const API_KEY = "callio_sk_xyz"; const resp = await fetch('callio/any_api' auth: API_KEY); Run 200 OK{"content": "Hi!"} Callio Proxy Target: Any API Add to Agent callio_sk_xyz api.provider.com Any API Provider

From signup to a calling agent in minutes

Quick setup. No SDK sprawl, no per-API auth flows.

Get one key

Sign up, grab a Callio key (sandbox or production). One key replaces dozens of provider signups for your agent.

Install in your agent

Drop the MCP server into Cursor, Claude, or Antigravity. Or call our HTTP proxy from any backend or agent runtime.

Ship to production

Watch traffic, retries, and errors in the dashboard. Move from sandbox to production keys when you're ready.

Drop into your agent stack

Use it from Node, Python, Go, or directly from your agent runtime. One HTTP path, one key, every upstream you care about.

Works with any language or framework

One unified proxy — just change the slug

Bring your own provider keys (BYOK)

Install the SDK

npm install callio-sdk

Initialize with your single Callio key

import { CallioClient } from 'callio-sdk';

const callio = new CallioClient('callio_your_api_key');

Call ANY API through the unified proxy

/* OpenAI */
await callio.post('openai', 'v1/chat/completions', {
    model: 'gpt-4',
    messages: [{ role: 'user', content: 'Hi!'}]
});
/* Same key, different API - just change the slug! */
await callio.post('sendgrid', 'v3/mail/send', {
    to: 'user@co.com', subject: 'Hello'
});

Built with Security

Your credentials, your control

Provider keys are AES-256 encrypted at rest. Callio keys are hashed. We never store request or response data.

Encrypted at rest

All provider credentials are AES-256-GCM encrypted before storage.

Zero data logging

Request and response bodies pass through — we only log metadata.

Built-in rate limits

Per-plan quotas and real-time usage monitoring from your dashboard.

MCP Server

Connect Antigravity, Cursor & more

Install the MCP server and your AI agent gets instant access to 143 APIs through the same unified gateway.

Antigravity→MCP Settings panel

Cursor→.cursor/mcp.json

Claude Code→~/.claude/claude_desktop_config.json

mcp config

{
    "mcpServers": {
        "callio": {
            "command": "npx",
            "args": ["-y", "github:hmadhsan/callio-mcp"],
            "env": {
                "CALLIO_API_KEY": "callio_your_key"
            }
        }
    }
}

A catalog tuned for agents

The categories agents actually need: search, comms, data, payments, identity, AI tooling, and more, all behind one key.

  • Search: Web, news, products
  • Email: Send, verify, find
  • Data: Enrich, scrape, extract
  • Messaging: SMS, chat, notifications
  • Analytics: Tracking, insights
  • Cloud: AWS, GCP, Azure
  • Identity: Auth, KYC, verify
  • Social: LinkedIn, X, Instagram
  • AI / ML: Models, embeddings
  • Dev Tools: GitHub, CI/CD, logs
  • Storage: Files, S3, CDN

And many more. New APIs added every week.

Built for teams shipping AI

Wherever your agent runs, Callio is the one external API surface in front of it.

Agent builders

Give your agent search, comms, data, payments, and more without writing a new client and auth flow for every provider.

AI-native startups

Ship faster with one gateway in front of every external API your product depends on. Skip the integration backlog.

Devs in Cursor & Claude MCP

Install our MCP server once and your editor or assistant can hit 143 APIs through Callio with the same key.

Frequently asked questions

What is Callio?
Callio is the API gateway for AI agents and AI-native apps. One key and one interface in front of 143 external APIs your agent or product needs to call.

How is this different from calling each API directly?
Instead of writing a client, auth flow, retry policy, and key rotation for every provider, you point your agent at Callio. We handle routing, auth injection, errors, and observability so you don’t maintain N integrations yourself.

Who is Callio for?
Teams building AI agents, AI-native SaaS, and dev tools that lean on a lot of external APIs. Typical user: a founder or engineer who wants to ship features instead of maintaining a folder full of API clients.

How does the MCP integration work?
Drop our MCP server into Cursor, Claude, Antigravity, or any MCP-compatible client and your agent can call every API in the catalog with the same Callio key.

Do I need provider keys for the upstream APIs?
For most providers you bring your own key once and Callio injects it on each request (BYOK). Some public APIs work without one. Either way, your provider credentials are encrypted at rest.

How much does it cost to start?
There’s a free tier with 500 proxy requests and 2 sandbox keys so you can actually build and test before paying. Paid plans start at $19/month (Builder) for real product traffic.

Get in touch

Have questions, feedback, or want to list your API? We'd love to hear from you.