Ask Claude or ChatGPT what’s overdue.
The OnDue connector puts your receivables in Claude and ChatGPT. Sign in with your OnDue login, choose the companies and what the app may do, and disconnect it whenever you like.
https://mcp.ondue.ai/mcp On every plan during early access, Solo included.
Set it up in Claude
On claude.ai and the Claude desktop app. Custom connectors are on Claude’s Free plan (one custom connector), Pro, Max, Ultra, Team and Enterprise. On Team and Enterprise, an owner adds the connector for the organization first.
Free, Pro, Max or Ultra
- Go to Customize > Connectors. In the desktop app, select Customize in the sidebar, then Connectors.
- Select Add, then Add custom connector.
- Name it OnDue, paste
https://mcp.ondue.ai/mcpas the server URL, and click Continue. - Keep the sign-in settings Claude marks Detected (OnDue registers Claude automatically, so there’s no client ID or secret to enter), then click Add.
- Click Connect. Sign in to OnDue (in the desktop app this opens your browser), pick the companies and permissions, and approve.
Team or Enterprise
An owner adds it once for the organization (on Enterprise, also anyone whose custom role lets them manage the organization’s libraries):
- Go to Organization settings > Connectors.
- Select Add, then Custom. If Claude asks for the type, choose Web.
- Name it OnDue, paste
https://mcp.ondue.ai/mcp, keep the settings marked Detected, and click Add.
Then each person connects with their own OnDue login, so each sees only their own companies and role: Customize > Connectors, find OnDue (it has the Custom label), click Connect and sign in.
Use it in a chat
Select + in the message box, then Connectors, and turn OnDue on for that conversation. Claude can ask before it uses a tool: Allow once or Always allow. To decide ahead, open OnDue under Customize > Connectors and set each tool under Tool permissions to Always allow, Needs approval or Blocked. We suggest Needs approval for approve_reminder.
From Claude’s help pages, read November 12, 2026: Claude: Add a connector that isn’t in the directory; Claude: Get started with connectors; Claude Help Center: custom connectors using remote MCP.
Set it up in ChatGPT
On ChatGPT on the web. Full support for custom MCP servers, including changes, is on Business and Enterprise/Edu. Pro can connect them for reading only. You don’t need to turn on developer mode first.
Add OnDue
On Business, an admin or owner does this. On Enterprise/Edu, an admin or owner, or a member an admin has allowed to connect custom MCP servers.
- Go to Plugins (chatgpt.com/plugins).
- Select the + button, then Add custom MCP server.
- Name it OnDue. Under Connection, enter
https://mcp.ondue.ai/mcp. - Set authentication to OAuth.
- Read the risk warning and tick I understand and want to continue.
- Select Create as a plugin and review the tools it found.
- Install the plugin and sign in to OnDue when asked: pick the companies and permissions, and approve.
Share it with your workspace
Only admins and owners publish a custom app for the workspace: Admin console, choose the workspace, Plugins, Manage Legacy Apps, Drafts, then Publish. People then find it under Settings > Plugins and connect with their own OnDue login. ChatGPT keeps a snapshot of the tools from when it was published, so an admin refreshes the tool list when OnDue adds one.
Use it in a chat
Start a new conversation, type @ in the message box and pick OnDue. By default, ChatGPT asks you to confirm actions that change things before it runs them.
From OpenAI’s help pages, read November 12, 2026: OpenAI Help Center: Connecting custom MCP servers in ChatGPT; OpenAI: Connect and test your plugin.
What you can ask
Plain questions about your own invoices. The app looks them up in OnDue, live, for the companies you connected.
- “Which Calder Mechanical invoices are over 30 days late?”Read
- “How much is overdue at Larkspur Engineering, by age?”Read
- “What’s our DSO estimate, and what share of invoices were paid on time?”Read
- “Which reminders are waiting for my approval, and what do they say?”Read
- “Did Brightwater Clinics reply about invoice 1041?”Read
- “Pause chasing Northgate Property Group and add a note that their AP lead is out.”Make changes
- “Make the Sable Freight reminder shorter and mention their PO number.”Make changes
- “Approve the reminder for invoice 1052.”Approve reminders
What it may do
You pick these when you connect. Every call is also limited to your role in that company and the company’s approval rules, exactly as in the app.
| Permission | Lets the AI app |
|---|---|
| Read your receivablesAlways on | Invoices, balances, aging, customers, reminders waiting for approval, replies and disputes, payments, promises to pay, the cash forecast, sync health, reminder settings, and late fees and interest. |
| Make changesOptional, ticked if the app asks for it | Add a team note, edit a waiting reminder’s wording, skip a reminder, pause or resume chasing for an invoice or a customer, mark a reply handled, create a pay link. None of these sends anything to a customer. |
| Approve remindersOptional, never pre-ticked | Approve a waiting reminder, which sends it to the customer. |
Never available to an AI app: settings, the team, the connection to your books, the payments setup and automatic mode.
The tools
27 tools: 19 to read, 7 to make changes and 1 to approve. You’ll see these names when the app asks before using one.
Read your receivables
list_companies- The companies this connection can use, your role in each, the books each is connected to, and what’s overdue.
get_receivables_overview- What the company is owed: open and overdue balances and counts, the five aging buckets, cash collected in the last 30 days, and how many reminders and replies are waiting.
get_collections_metrics- Share of the balance that’s overdue, average days past due weighted by balance, average days late and on-time share for invoices paid in the last year, cash collected in the last 30 and 90 days, and a DSO estimate (see the questions below for how it’s worked out).
get_aging_by_customer- Open balances by customer with the aging buckets for each, largest overdue first.
list_customers- Customers with open invoices, and how many each has.
get_customer_summary- One customer: every open invoice with its balance, days overdue and where chasing stands, totals and aging, pauses, their cadence and replies that need attention.
list_invoices- Open invoices, latest due first. Filter to overdue or paused, or search by invoice number or customer.
get_invoice- One invoice in full: its timeline of reminders, replies, pauses and payments, the planned reminders and the team’s notes.
list_reminders_awaiting_approval- Drafted reminders waiting for a person: recipients, subject and body, and whether you may approve each one under your role and the approval rules.
list_replies- Replies and disputes that need a person, with OnDue’s classification and summary.
list_promises_to_pay- Promises to pay, with the week each is expected.
list_payments- Payments received in the last 90 days: from your books, OnDue’s pay page or a matched bank deposit.
get_cash_forecast- The 13-week cash forecast: low, expected and high per week, with the reason for each invoice if you ask.
list_paused_chasing- Invoices and customers where chasing is paused: what, why, when and by whom.
get_sync_health- Whether your books are syncing, and anything holding reminders back.
get_reminder_settings- How the company chases: Ask me first or automatic mode, the cadence, sending hours and approval rules. Read only.
list_late_fees- Late fees and interest OnDue proposed or charged (QuickBooks Online companies with late fees on). Read only: fees are approved or waived in OnDue.
search, fetch- Find open invoices and customers by number or name, and open one in full. ChatGPT uses these two for deep research and company knowledge.
Make changes
add_invoice_note- Add a note to an invoice for the team. Never sent to the customer or written to your books.
edit_reminder_draft- Change the subject or body of a waiting reminder, or go back to the AI draft. It still waits for approval.
skip_reminder- Skip one waiting reminder, so it’s never sent. Later steps still happen.
pause_chasing- Stop chasing one invoice, or every open invoice of a customer, until resumed.
resume_chasing- End a pause, so OnDue chases those invoices again under your settings.
mark_reply_handled- Mark a reply or dispute as handled, and optionally resume chasing that invoice.
create_pay_link- Get an invoice’s pay link to share yourself. Nothing is sent.
Approve reminders
approve_reminder- Approve a waiting reminder exactly as drafted. OnDue sends it to the customer within 15 minutes.
Security, and how to disconnect
More on how OnDue is built on the security page. To disconnect, open Settings in OnDue, then AI apps.
- Sign-in
- You sign in with your OnDue login on app.ondue.ai: password, emailed code, passkey or your company’s single sign-on. Claude and ChatGPT never see your password.
- Your choice
- Before anything connects, OnDue shows which app is asking, where it will send you back, the companies you can pick and all three permissions. Read is always on, Make changes is ticked only if the app asked for it, and Approve reminders is never ticked for you. Continue only if you started connecting yourself; if someone sent you the link, close the tab.
- Limits
- Every call is limited to your role in that company and the company’s approval rules, exactly as in the app. An AI app never gets more than you have. It can’t change settings, the team, the connection to your books or the payments setup, and it can’t turn on automatic mode.
- Audit trail
- Every tool call is logged in OnDue’s audit trail, and approvals, skips and edits are recorded as made through an AI app.
- Rate limit
- 120 tool calls a minute per connection.
- Hosting
- Amazon Web Services, like the rest of OnDue.
- Your conversation
- What OnDue returns goes into your conversation with Claude or ChatGPT, and they handle it under their own terms. Connect only the companies you want there.
- Disconnect
- Settings > AI apps, in the web app or the Android app, lists every app you’ve connected, when it was last used and what it may do. Disconnect stops it at once. A connection also ends after a year (30 days when you connected from a single sign-on session), when you reset your password or use two-step recovery, and when you leave every company it covers.
Questions
Does the connector cost extra?
No. It’s on every plan during early access, Solo included. Billing hasn’t started, so nobody is charged.
Can Claude or ChatGPT send a reminder without me?
Only if you tick Approve reminders when you connect, and only within your role and the company’s approval rules. Approving a reminder sends it to the customer. ChatGPT asks you to confirm actions that change things by default, and in Claude you can set approve_reminder to Needs approval so it always asks. Leave Approve reminders unticked and the AI app can read, and make changes if you allow it, but a person approves in OnDue.
Can it change anything in QuickBooks Online, Xero, Odoo or Stripe Billing?
No. The connector works on OnDue: notes, reminders, pauses and replies. It has no tool that writes to your books.
How is the DSO estimate worked out?
DSO is usually receivables divided by credit sales over a period. OnDue doesn’t see your total credit sales, only the invoices you chase and the payments that come in, so it uses cash collected in the last 90 days instead. Call it a DSO estimate, and use your books for the reported figure.
Which Claude and ChatGPT plans can use it?
As their help pages said on November 12, 2026: in Claude, custom connectors are on the Free (one custom connector), Pro, Max, Ultra, Team and Enterprise plans, and on Team and Enterprise an owner adds the connector first. In ChatGPT, custom MCP servers with full support are on Business and Enterprise/Edu, on the web, added by an admin or owner (or a member an Enterprise/Edu admin allows). ChatGPT Pro can connect them with read and fetch permissions only, so OnDue’s change and approve tools aren’t available there. Plans change, so check the Claude steps and the ChatGPT steps for the source pages.
I look after several companies. What does the AI app see?
Only the companies you pick when you connect, and only with the role you have in each. You can connect again with a different set, and disconnect any connection in Settings > AI apps.
Does it work with other AI apps?
Any app that connects to remote MCP servers with OAuth sign-in can use https://mcp.ondue.ai/mcp. This page covers Claude and ChatGPT, which we’ve set up step by step.
Can I use it on my phone?
In Claude, a connector you connect on the web or the desktop app is there in the Claude mobile app too. ChatGPT says custom MCP servers are web only. You can disconnect from the OnDue Android app either way.
Next time an invoice goes late, let OnDue draft the first email.