CallChatSyn API

Use your business's CallChatSyn answering bot and booking calendar from your own website, app or AI agent. Same answers your customers get on WhatsApp and your booking page. Machine-readable spec: openapi.json.

Try it now, no sign-up

Use the public demo key ccs_demo_public with any example below. It answers as our demo business, and bookings are dry runs: you see the time would be booked, but nothing is saved. It allows 30 calls per 10 minutes per visitor. Try it right here:

Or from your terminal:

curl https://callchatsyn.com/api/v1/answer \
  -H "Authorization: Bearer ccs_demo_public" \
  -H "Content-Type: application/json" \
  -d '{"message": "Where are you located?"}'

1. Get a key

In Dashboard → Developers, create a key. It's shown once; keep it on your server, never in browser code. Send it on every request as Authorization: Bearer ccs_live_….

2. Answer a customer's message

curl https://callchatsyn.com/api/v1/answer \
  -H "Authorization: Bearer $CCS_KEY" \
  -H "Content-Type: application/json" \
  -d '{"message": "What are your opening hours?"}'

# {"intent":"faq","lang":"en","matched":true,"reply":"We're open Monday to Friday 9am to 5pm, and weekends 9am to 9pm."}

3. Book an appointment

Already on Cal.com? Connect it in Dashboard → Appointments. Open times then come from your Cal.com calendar and bookings go straight into it; the endpoints stay the same.

curl https://callchatsyn.com/api/v1/slots -H "Authorization: Bearer $CCS_KEY"
# {"slots":[{"start":"2026-10-10T02:00:00.000Z","label":"Sat 10 Oct, 10:00"}],"services":["Haircut"],"locations":["Main St"]}

curl https://callchatsyn.com/api/v1/bookings \
  -H "Authorization: Bearer $CCS_KEY" -H "Content-Type: application/json" \
  -d '{"start":"2026-10-10T02:00:00.000Z","service":"Haircut","name":"Ana","email":"ana@example.com"}'

# 201 {"booked":true,"id":"83a350ef-…","start":"2026-10-10T02:00:00.000Z","label":"Sat 10 Oct, 10:00"}

4. Cancel a booking

Use the id from the booking. With Cal.com connected, it's cancelled there too. To reschedule, cancel and book a new time.

curl -X DELETE https://callchatsyn.com/api/v1/bookings/$BOOKING_ID -H "Authorization: Bearer $CCS_KEY"

# 200 {"cancelled":true,"id":"83a350ef-…","start":"2026-10-10T02:00:00.000Z"}
# 404 unknown id · 409 already cancelled

Use it with WhatsApp

Have a WhatsApp number on Twilio or Meta's Cloud API? Forward messages to the API and reply with its answers and booking menu. Step-by-step with tested code: WhatsApp guide.

Use it from an AI assistant (MCP)

The open-source callchatsyn-mcp server gives Claude, Cursor and other MCP clients four tools: answer a customer question, list open times, book an appointment, cancel an appointment.

Nothing to install: add the remote server URL as a custom connector (Claude: Settings → Connectors → Add custom connector). With no key it uses the demo business; send Authorization: Bearer ccs_live_… to use your own.

https://callchatsyn.com/api/mcp

Or run it locally:

{
  "mcpServers": {
    "callchatsyn": {
      "command": "npx",
      "args": ["-y", "github:oneappsworld/callchatsyn-mcp"],
      "env": { "CALLCHATSYN_API_KEY": "ccs_live_..." }
    }
  }
}

Errors and limits

• Errors look like {"error":{"code":"…","message":"…"}}.
• With the demo key, POST /api/v1/bookings returns 200 with {"booked":false,"demo":true} instead of booking.
• 401 bad key · 402 plan inactive · 403 feature not in plan · 429 usage limit · 400/404/409 request problems.
• Each request counts toward the business's plan limits, the same as WhatsApp and booking-page messages.
• The answering bot, order status and bookings are included on the Pro plan. Founder offer: the first 1,000 businesses to claim it in Dashboard → Developers get them free on any plan (up to 100 API calls a day, 2,000 a month).

Comparing options? See vs Calendly API, vs Cal.com API and vs Chatbase API.