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Ask ChatGPT to send WhatsApp messages, look up contacts and organise your ChatSyncs account.

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Before you start

  • ChatGPT on the web (chatgpt.com). Custom MCP servers don’t work in the mobile apps.
  • A plan that allows custom MCP servers. What you can do depends on the plan:
  • Your ChatSyncs API key, from the API Developer Console. How to find it.
OpenAI changes these limits often. If you need ChatGPT to send WhatsApp messages and it refuses, Claude can do every ChatSyncs action on any paid plan.

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Connect

1

Open Plugins

On chatgpt.com, go to chatgpt.com/plugins. You can also open it from the sidebar.
2

Create the ChatSyncs server

Click Add (top right), then Create custom MCP server.If Create custom MCP server isn’t in the menu, your plan or workspace doesn’t allow it yet. See I can’t find Create custom MCP server.
3

Fill in the form

  • Name: ChatSyncs
  • Description: My WhatsApp business on ChatSyncs
  • Connection: keep Server URL selected and paste:
  • Authentication: OAuth. Leave Advanced OAuth settings alone: ChatGPT finds everything it needs by itself.
Tick I understand and want to continue, then click Create.
4

Paste your key on the ChatSyncs page

A ChatSyncs page opens saying “ChatGPT wants to access your ChatSyncs account”. Paste your API key and click Authorize ChatGPT. You’ll see Connected as your business name, then you’re sent back to ChatGPT.
5

Use it in a chat

Start a new chat and type @ChatSyncs in the message box, or open ChatSyncs on the Plugins page and click Try in chat.

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For workspace admins

On Business, Enterprise and Edu, only admins and owners (and, on Enterprise and Edu, members given developer access) can add custom MCP servers:
  1. Turn on developer mode in Workspace settings → Permissions & Roles → Connected Data. On Enterprise and Edu you can also give it to chosen members with RBAC; they then switch it on in Settings → Apps → Advanced settings.
  2. Create the app from Workspace settings → Apps → Create, with the same name, URL and OAuth setting as above. Click Scan Tools, complete the ChatSyncs sign-in, then click Create.
  3. Test the draft in a chat, then publish it from Workspace settings → Apps → Drafts → Publish. Review the warnings about write actions; ChatSyncs can send messages.
Members then find ChatSyncs in their apps. The first time they use it, they paste their own ChatSyncs API key on the ChatSyncs page.
A published workspace app keeps a frozen copy of ChatSyncs’s tool list. When ChatSyncs adds or changes a tool, an admin has to refresh it (Enterprise and Edu: Workspace settings → Apps → … → Action control → Refresh) or, on Business, delete the app and create it again. Until then, a changed tool can fail with an error.

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Check it worked

In a chat, type @ChatSyncs and ask:
“What’s my ChatSyncs account name and which WhatsApp numbers are connected?”
ChatGPT calls ChatSyncs and answers with your business name and numbers. If it answers from general knowledge instead, start your message with @ChatSyncs again.

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Disconnect

Open chatgpt.com/plugins, click ChatSyncs in the sidebar’s Installed list, and use the … menu to disconnect or remove it. Workspace admins remove a published app from Workspace settings → Apps. To cut off every app that has your key, regenerate it.

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Frequently asked

No. Anything that sends, changes or deletes is a “write action”, and ChatGPT asks you to confirm it, showing exactly what it’s about to send. You can choose to remember your answer for the rest of that conversation. Only do that if you’re comfortable with it sending without asking.
Yes. Open ChatSyncs on the Plugins page and click the app under Apps to see every tool, split into read and write. Workspace admins on Enterprise and Edu can switch individual actions off with Action control; for example, turn off delete_subscriber.
Mention it with @ChatSyncs in the message where you want it. A choice applies to that message; mention it again when a later question needs fresh ChatSyncs data.
Check you’re on chatgpt.com in a browser (not the phone app) and on a paid plan. On a company workspace, your admin has to enable developer mode for you first. On some accounts the switch is in Settings → Apps → Advanced settings → Developer mode.
That’s ChatSyncs answering correctly: the account whose key you pasted has no WhatsApp number connected yet. Connect one in ChatSyncs, or reconnect ChatGPT with the key of the account that has your number.

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Gotchas

  • Web only. Custom MCP servers don’t appear in the ChatGPT phone apps.
  • ChatGPT ignores ChatSyncs and guesses. Start the message with @ChatSyncs.
  • Authentication set to “No authentication”. ChatGPT then can’t reach your account and every action fails. Remove the server and create it again with OAuth.
  • “ChatSyncs did not accept that key.” Copy the key again, with no spaces before or after.
  • Sending is refused on a personal plan. That’s ChatGPT’s own limit on personal plans, not a ChatSyncs error. See the plan table under Before you start.