API marketplace for agents

One gateway for every API
your agents need.

Give your agents access to any API — search, payments, email, data, and more. Authentication, discovery, and execution handled automatically.

Get Started Free Browse APIs

50+

APIs available

API key needed

<2 min

Setup time

99.9%

Uptime SLA

Works withOpenAI Codex·Claude Code·Cursor·LangChain·CrewAI·& more

How it works

Three steps. That's it.

Connect once

Get a single API key. That's your access to the entire Callio marketplace — no per-API setup.

Discover APIs

Browse or let your agent search for the right API. Callio handles auth, rate limits, and routing.

Execute & ship

Call any API through one unified endpoint. Your agent handles the rest — you ship faster.

Simple to integrate

One API key. One endpoint. Every API your agent needs — no boilerplate, no per-service auth headaches.

Works with any language or framework

One unified proxy — just change the slug

Bring your own provider keys (BYOK)

# 1. Install the SDK

npm install callio-sdk

# 2. Initialize with your single Callio key

import { CallioClient } from 'callio-sdk';

const callio = new CallioClient('callio_your_api_key');

# 3. 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 Claude Code, Cursor & more

Install our MCP server and your AI agent gets instant access to 50+ APIs. Search, browse, and call any API using natural language.

Claude Code→~/.claude/claude_desktop_config.json

Cursor→.cursor/mcp.json

Antigravity→MCP Settings panel

Setup guide View source

mcp config

{

"mcpServers": {

"callio": {

"command": "npx",

"args": ["-y", "github:hmadhsan/callio-mcp"],

"env": {

"CALLIO_API_KEY": "callio_your_key"

}

APIs for everything

Search, payments, AI, scraping, messaging — all accessible through one gateway.

Web, news, products

Send, verify, find

Payments

Stripe, billing

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

Whether you build agents or provide APIs — Callio is for you.

AI developers

Give your agents real-world capabilities. One API key to search the web, send emails, process payments, enrich data, and more.

API providers

List your API on Callio and get instant distribution to thousands of AI agents. No sales team needed — agents discover and use your API automatically.

Startups

Ship in days, not months. Skip the infrastructure work — Callio handles auth, rate limiting, and routing so you can focus on your product.

Frequently asked questions

What is Callio?

Callio is an API marketplace and gateway built for AI agents. It lets your agents discover, authenticate, and call any API through a single unified interface.

How is this different from just calling APIs directly?

With Callio, you don't manage individual API keys, handle different auth flows, or write custom integration code for each API. One setup, all APIs.

Who is Callio for?

AI developers building agent workflows, API providers wanting distribution to AI agents, and startups that need to ship fast without infrastructure overhead.

Is there a free tier?

Yes. We have a generous free tier for developers. Sign up to get started instantly.

Can I add my own API to Callio?

Absolutely. API providers can list their APIs on Callio and get instant distribution to thousands of AI agents. Book a demo to learn more.

See it in action

Pick a time and we'll walk you through everything — tailored to your use case.

Schedule a call

20-min session Tailored walkthrough No commitment

Get in touch

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

One gateway for every API your agents need.