How Callio works

One key. One gateway. Every external API your agent or AI-native app needs to call, MCP-native and production-ready.

Pick the tools your agent needs

Browse the catalog by category: search, comms, data, payments, identity, AI tooling, and more. The right APIs for whatever your agent has to do, in one place.

Browse APIs

📧 SendGrid
🤖 OpenAI
💬 Slack
📊 Analytics
🔍 Scraper
🌐 Globe

Get one key (sandbox or prod)

Generate a Callio key from your dashboard. Use a sandbox key while you build, switch to a production key for real traffic. One key authenticates every API in the catalog.

Your Callio API Key

callio_a1b2c3d4e5f6g7h8i9j0k1l2

Works with every API — no extra keys needed

Call from MCP or HTTP

Drop our MCP server into Cursor / Claude / Antigravity, or call the HTTP proxy directly from any backend or agent runtime. We handle auth, retries, and observability.

curl -X GET \
  "https://callio.dev/api/proxy/jsonplaceholder/posts/1" \
  -H "Authorization: Bearer callio_..." \

# Response
{
  "data": [...],
  "has_more": false
}

Why agent builders choose Callio

One key, every tool

No more juggling N provider signups and N auth flows. One Callio key handles the whole catalog.

MCP-native

Plug into Cursor, Claude, and Antigravity in minutes. Your agent gets discovery, describe, and call as three tools.

BYOK + encrypted

Save your provider keys once. They’re AES-256 encrypted at rest and injected at the proxy, never exposed in logs.

Sandbox + production

Build against a sandbox key, ship with a production key. Same gateway, separate quotas and traffic.

Just HTTP

No vendor SDK lock-in. Call from any language or agent runtime that can speak HTTP.

Observability built in

See every routed call, status, and provider error in the dashboard. Trust the path your agent depends on.