ChatGPT
Set up SimpliServ as a plugin in ChatGPT – enable developer mode, enter the MCP server URL, sign in via OAuth and set permissions
→ Create the plugin in ChatGPT · Open ChatGPT plugins · Open the MCP connector
Set up SimpliServ as a plugin in ChatGPT: it can then read your customers, orders, invoices and inventory – and, after your confirmation, perform actions too.
You need a ChatGPT account on Plus, Pro, Business or Enterprise and a SimpliServ user with the MCP interface → Access permission. No API key is required – authentication runs through OAuth. For other clients (Claude, Cursor), see MCP.
Setup
Enable developer mode
Custom MCP servers can only be added in developer mode. Open → Security and login in ChatGPT, scroll all the way down to Developer mode and turn on the toggle.
ChatGPT flags developer mode as elevated risk because it allows unverified servers to be connected. Only connect servers you trust – with SimpliServ that is your own workspace.
Open the plugin dialog
→ Open the plugin dialog directly
Alternatively: click Plugins in the sidebar, then the + at the top right next to the search box.
Fill in the fields
In the New Plugin dialog, enter the following – each block has a copy button on the right:
Icon (optional) – PNG only, 10 KB maximum: → download the SimpliServ icon
Name
SimpliServDescription (optional)
Access to customers, orders, invoices and inventory in SimpliServConnection – leave the mode on Server URL, then:
https://api.simpliserv.app/api/v1/mcpAuthentication – in the dropdown:
OAuth
The URL is identical for every workspace. You can leave Advanced OAuth settings untouched: ChatGPT discovers the client ID, secret and endpoints on its own.
Finally confirm the risk notice with I understand and want to continue and click Create.
Sign in and consent
ChatGPT opens the SimpliServ login. Sign in with your workspace user and confirm the consent screen. The plugin then shows "Connected to SimpliServ" along with the available actions.
Set permissions
Under Permissions you decide when ChatGPT asks: on every action, only on risky ones, or never (Allow all actions). Asking on write operations is the safe choice.
Using it in a chat
The plugin is available in new conversations – via the plugin menu in the composer or by addressing it directly, e.g. "Show me the open invoices for customer Müller".
A connected plugin inherits your user's roles and permissions – it sees and may do only what you see and may do. See Users & roles.
Multiple workspaces
If you belong to several workspaces, the plugin always works with your default workspace. Unlike the web interface, you cannot switch inside a chat: ChatGPT sends no workspace identifier, so the server falls back to your default.
Access to other workspaces is ruled out – your membership is checked on every request. If ChatGPT answers with data from the wrong workspace, ask support to change your default workspace.
Revoking access
Two ways, both effective immediately:
- In ChatGPT: open Plugins → SimpliServ → remove it via the … menu.
- In SimpliServ: in the MCP connector under Authorized OAuth clients click Revoke. This ends active sessions and invalidates all access tokens.
Troubleshooting
| Symptom | Cause and fix |
|---|---|
| No + button in the plugin overview | Developer mode is off, or your plan does not allow custom servers. Check step 1. |
| "Could not connect" while creating | Check the URL exactly: https://api.simpliserv.app/api/v1/mcp, without a trailing slash. |
| Sign-in works but no actions appear | Your user is missing the MCP interface → Access permission – see Users & roles. |
| Data from the wrong workspace | The plugin always uses your default workspace, see Multiple workspaces. |
| The icon is rejected | PNG only, 10 KB maximum. Use the SimpliServ icon. |
| The plugin returns no data | Your permissions apply. What you cannot see in SimpliServ, ChatGPT cannot see either. |
Related topics
MCP
Overview of the MCP server plus Claude, Cursor and authorized clients.
Connect Claude
The same integration for Claude.
Manage connectors
The connector hub: connect, configure and disconnect integrations.
API access & external apps
Issue API keys and connect external apps.
Users & roles
Control the permissions a connected plugin inherits.
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