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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 Plus, Pro, Business, Enterprise or Edu. The Free plan can’t add custom apps.
  • ChatGPT on the web (chatgpt.com). Custom MCP apps don’t work in the mobile apps.
  • On Business, Enterprise or Edu: an admin has to allow it first. See For workspace admins.
  • Your ChatSyncs API key, from the API Developer Console. How to find it.
ChatGPT calls this Developer mode. Despite the name, you don’t need to write code. It’s the setting that lets ChatGPT use apps that aren’t in its built-in directory, such as ChatSyncs.

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Connect

1

Turn on Developer mode

On chatgpt.com, open Settings → Security and login and switch on Developer mode. Read the warning and confirm.
2

Create the ChatSyncs app

Go to chatgpt.com/plugins and click the + button.
3

Fill in the details

  • Name: ChatSyncs
  • Description: My WhatsApp business on ChatSyncs
  • MCP server URL:
  • Authentication: OAuth. Leave any client ID and client secret fields empty.
If there’s a box asking you to confirm you trust this app, tick it. 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. Click + in the message box, choose Developer mode, and select ChatSyncs.

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For workspace admins

On Business, Enterprise and Edu, ChatGPT only lets admins and owners create custom apps:
  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.
  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 settings. The first time they use it, they paste their own ChatSyncs API key on the ChatSyncs page.
On Business plans, a published app can’t be edited. To change it, delete it and create it again.

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Check it worked

In a chat with Developer mode → ChatSyncs selected, ask:
“List my WhatsApp templates.”
ChatGPT calls ChatSyncs and lists your templates. If it answers from general knowledge instead, say “Use the ChatSyncs app to list my WhatsApp templates.”

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Disconnect

Open chatgpt.com/plugins (or Settings → Apps), open ChatSyncs, and disconnect or delete 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. Each app has a details page in ChatGPT’s app settings where you can switch individual tools off. For example, turn off delete_subscriber.
Yes. Choose Developer mode → ChatSyncs from the + menu in each new conversation.
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 it first.

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Gotchas

  • Web only. Custom apps don’t appear in the ChatGPT phone apps.
  • ChatGPT ignores ChatSyncs and guesses. Mention it by name: “Use ChatSyncs to…”.
  • Authentication set to “No authentication”. ChatGPT then can’t reach your account and every action fails. Delete the app and create it again with OAuth.
  • “ChatSyncs did not accept that key.” Copy the key again, with no spaces before or after.