quaderno for ChatGPT

io.usefulapi/quaderno

MCP server for Quaderno — tax-rate calculation, invoices, contacts, products, receipts & expenses.

client:ChatGPT transport:streamable-http

Install quaderno in ChatGPT

Settings → Connectors → Advanced → Developer mode

https://quaderno.usefulapi.io/mcp

Custom connectors are a paid-plan feature and take a remote URL only. ChatGPT cannot run a packaged server locally. ChatGPT docs