Connect Diagonalise to Claude, ChatGPT or GitHub Copilot. Then just ask: raise an invoice, log a receipt, find out who owes you, or check your profit for the tax year so far.
Read only on Free. Read and write on Professional. See pricing
Who owes me money, and is anything late?
You're owed £4,860.00 across 5 unpaid invoices. Two are past their due date:
Shall I draft a polite reminder to Hart & Co?
Log £42.50 for printer ink from Ryman yesterday.
Done: £42.50 at Ryman, filed under Office Supplies, which goes in box 23 of your Self Assessment.
Create, edit and copy invoices, record payments, share the link your client pays from, and fetch the PDF.
Record and correct expenses, filed under your categories and the matching HMRC box.
Find clients by name, company or postcode, add new ones, and bill your saved products and prices.
Income, expenses and profit for any UK tax year or date range, month by month, on the cash basis.
Turnover and expenses by SA103 box, with an indicative Income Tax and Class 4 NI estimate.
It understands 6 April to 5 April, so "this tax year" means what you mean.
In Claude, ChatGPT or VS Code, add a connector with the address www.diagonalise.com/mcp.
Sign in to Diagonalise, pick the business, and choose read only or read and write.
Your assistant now has the tools it needs. Ask it anything you'd do in the app.
Prefer an API key? Create a personal access token on the AI & API page in your account and use it with Claude Code, the OpenAI API or your own scripts.
Your assistant gets exactly the access you approve, and you can take it back at any time.
It is an MCP (Model Context Protocol) server at https://www.diagonalise.com/mcp. AI apps that support MCP can use it to read and update your Diagonalise account when you ask them to: invoices, expenses, customers, products and your UK tax year reports.
Claude (claude.ai and the Claude desktop and mobile apps, as a custom connector), ChatGPT (as a connector in developer mode), GitHub Copilot in VS Code, Claude Code, and other apps that can connect to a remote MCP server using OAuth sign-in or an API token.
Add https://www.diagonalise.com/mcp as a connector in your AI app. When it asks, sign in to Diagonalise, choose the business, choose read only or read and write, and approve. Step-by-step instructions for each app are on the AI & API page inside your account.
No. It works as you, so it can never do more than your own role allows, and you choose read-only or read-and-write access when you connect. It cannot change your settings, billing, payment methods or team, and it cannot send anything to HMRC.
No. It can create and update invoices, mark them paid and give you a link to the PDF, but sending invoices and filing your Self Assessment stay with you.
Yes, at any time from the AI & API page in your account. Access stops immediately, and so do any invoice PDF links it created. Those links expire after 15 minutes anyway.
Diagonalise only sends data to the AI app you connect, and only when it asks. How that app stores and uses your conversations is set by its own terms and privacy settings, so check those with your AI provider.
AI assistants are included at no extra cost from Diagonalise: read only on Free. Read and write on Professional. Personal access tokens for the API are on the Professional plan. You also need an account with the AI app you use.
Free to start, with 30 days of Professional included. No card needed.
Start free