Invoice Simple MCP Server
Invoices, estimates, clients and payments in Invoice Simple.
ホスト型 MCP サーバー
npx add-mcp 'https://cotlet.dev/mcp/v1/invoice-simple'Claude Code、Codex、Cursor などにインストールできます
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Invoice Simple MCP server: Let your AI agent do your Invoice Simple paperwork.
Invoice Simple has no MCP server, no ChatGPT or Claude app and no public API: we found no developer documentation or API keys, only built-in payment integrations (checked 8 Nov 2026). Cotlet runs 10 Invoice Simple tools hosted, over MCP for agents and REST for scripts, in your own Invoice Simple login.
Your AI agent writes invoices from your job notes, sends estimates, turns accepted ones into invoices and tells you who is late paying. Sign in to Invoice Simple once in your own Cloud Browser. No API needed.
- Free 7-day trial, no card
- Unofficial, not affiliated with Invoice Simple
- Page: https://cotlet.dev/integrations/invoice-simple-api-mcp-server
What can your AI agent do in Invoice Simple?
- Create invoices from job notes
- Send invoices and estimates
- Turn accepted estimates into invoices
- Chase overdue invoices
- Mark payments received
- See what each client owes
Does Invoice Simple have an MCP server or an API?
- Invoice Simple plans list built-in payment integrations, not an API.
- Its page for AI assistants describes the product; it is not an integration.
- Invoice Simple has no connector in the ChatGPT apps directory or in Claude.
| What you need | Invoice Simple API | By hand | Cotlet |
|---|---|---|---|
| Create an invoice | No API | Yes, one by one | Yes |
| Send invoices and estimates | No API | Yes, one by one | Yes, after your OK |
| Overdue list | No API | Yes, a filter | Yes |
| Ask in ChatGPT or Claude | No | No | Yes |
Checked 8 Nov 2026. Sources: Invoice Simple pricing, Invoice Simple help center, Invoice Simple information for AI assistants
How does the Invoice Simple MCP server work?
- Sign in to Invoice Simple. Once, in a browser we host for you.
- Connect your AI agent. One address in its settings.
- Hand it the busywork. It drafts the work, you OK what customers get.
We never keep your Invoice Simple password, and no invoice, estimate or payment goes through until you approve it.
How to connect Invoice Simple to your AI agent
Step by step with screenshots for ChatGPT, Claude, Grok and other agents: How to connect Invoice Simple to ChatGPT, Claude and AI agents.
- Sign in to Invoice Simple in a Cloud Browser. Create a Cotlet account, open Invoice Simple in its Cloud Browser, sign in on app.invoicesimple.com and press Enable for agents.
- Add the Cotlet address. Enter https://cotlet.dev/mcp/v1 as the MCP server or connector URL in your agent.
- Let the agent in. Chat apps open a Cotlet sign-in page. Editors, n8n and scripts send an API key made in the console.
Invoice Simple shares the address https://cotlet.dev/mcp/v1 with every other app you enable, so one connector covers them all. Turned Invoice Simple on after connecting? Refresh the connector and the 10 tools appear.
Claude:
Settings > Connectors > Add custom connector
URL: https://cotlet.dev/mcp/v1/connect
Claude Code:
claude mcp add --transport http cotlet \
https://cotlet.dev/mcp/v1 \
--header "Authorization: Bearer $COTLET_API_KEY"
ChatGPT:
Settings > Apps & Connectors > Create
MCP server URL: https://cotlet.dev/mcp/v1/connect
Authentication: OAuth
Cursor:
// ~/.cursor/mcp.json
{
"mcpServers": {
"cotlet": {
"url": "https://cotlet.dev/mcp/v1",
"headers": { "Authorization": "Bearer ${env:COTLET_API_KEY}" }
}
}
}
Codex:
# ~/.codex/config.toml
[mcp_servers.cotlet]
url = "https://cotlet.dev/mcp/v1"
bearer_token_env_var = "COTLET_API_KEY"
n8n:
MCP Client Tool (inside an AI Agent)
Transport: HTTP Streamable
URL: https://cotlet.dev/mcp/v1
Auth: Bearer, <your key>
Tool: invoice_simple_read
Make, Zapier:
Make: MCP Client > Call a tool
Zapier: MCP Client by Zapier > Run Tool
Server URL: https://cotlet.dev/mcp/v1
Token: <your key>
Tool: invoice_simple_write
All 10 Invoice Simple MCP tools
Invoices
New invoices start as drafts with your default terms and tax. Sending and marking paid wait for your OK.
- List invoices (
list_invoices, read): Invoices by status, client or date, with balances. - Get invoice (
get_invoice, read): One invoice with lines, tax, payments and history. - Create invoice (
create_invoice, write): Creates a draft invoice for a client. - Send invoice (
send_invoice, write, asks first): Emails an invoice to the client. - Mark invoice paid (
mark_invoice_paid, write, asks first): Records a payment on an invoice.
Estimates
Estimates start as drafts; an accepted one becomes a draft invoice with the same lines.
- List estimates (
list_estimates, read): Estimates by status or client. - Create estimate (
create_estimate, write): Creates a draft estimate for a client. - Send estimate (
send_estimate, write, asks first): Emails an estimate to the client. - Convert estimate to invoice (
convert_estimate, write): Turns an estimate into a draft invoice.
Clients
Clients with contact details and the total of their unpaid invoices.
- List clients (
list_clients, read): Clients with contact details and what they owe.
Inputs, REST path and example response of every tool: https://cotlet.dev/integrations/invoice-simple-api-mcp-server#tools
Who can see my Invoice Simple session, and how do I revoke it?
- What we store. Your signed-in Invoice Simple profile, AES-256-GCM encrypted, in Finland. No password.
- What your agent gets. The 10 Invoice Simple tools, never the session cookie.
- What the session sees. What your login sees: clients, invoices, estimates, payments.
- What no tool touches. Card charges, payment settings, subscription, deletes.
- If Invoice Simple signs you out. You sign in again yourself, in the same Cloud Browser.
- How to cut access. Disable for agents, reset the browser, or change your Invoice Simple password.
Cotlet never types your password: you sign in yourself, and the agent only uses the session. Our site scores A+ on Qualys SSL Labs, securityheaders.com and Mozilla Observatory (live results).
What happens when Invoice Simple changes?
- 12 h between tests of the Invoice Simple reads
- 24 h between tests of sends a customer would notice
- $0 for a call to a Invoice Simple tool paused for repair
When Invoice Simple moves the Send button or renames an invoice status, we fix the tool and your agent calls it the same way. status.cotlet.dev checks the site, console and API every 3 minutes.
Approvals, undo and mistakes
- Reads your job notes. Client, lines, rates and due date.
- Creates a draft. With your default terms and tax.
- Shows you the total. Line by line, before anything goes out.
- Waits, then sends. The send shows up in your Cotlet console first.
| Action | Undo |
|---|---|
| Create an invoice or estimate | Yes, edit or delete the draft |
| Convert an estimate | Yes, delete the new draft |
| Mark an invoice paid | Remove the payment in Invoice Simple |
| Send an invoice or estimate | No |
3 of 10 tools ask first: send_invoice, mark_invoice_paid, send_estimate. Draft invoices, draft estimates and conversions reach no customer, so they run at once. You can turn the wait off per tool once you trust a routine.
MCP call:
{
"name": "send_invoice",
"arguments": {
"invoice_number": "INV0151"
}
}
REST:
curl -X POST https://cotlet.dev/api/v1/invoice-simple/invoices/INV0151 \
-H "Authorization: Bearer $COTLET_API_KEY"
Response:
{
"invoice_number": "INV0151",
"status": "Sent",
"sent_to": [
"maria@example.com"
]
}
A cron job or n8n flow can call the same tools over REST at /api/v1/invoice-simple with the same key and price, in JSON. Failed calls are free. Each tool row above shows its REST path.
How much does the Invoice Simple MCP server cost?
About $19 a month for a one-person tile contractor, 3,270 credits. Your Invoice Simple plan stays as it is.
| Job | Calls | Credits |
|---|---|---|
| Invoice from job notes, sent | 3 × 30 | 900 |
| Estimate built and sent | 2 × 15 | 300 |
| Overdue list, weekly | 4 × 4 | 160 |
| Accepted estimate to invoice | 2 × 8 | 160 |
| Payment marked | 1 × 25 | 250 |
| Cloud Browser, 30 days | 1,500 | |
| Total | 3,270 |
- Free 7-day trial, no card
- 10 credits per successful call, MCP or REST
- 50 credits a day for the Cloud Browser
- Works on your current Invoice Simple plan
Invoice Simple publishes no invoice counts, so the month is our example. Dollars at the $29 pack rate.
Invoice Simple MCP server on GitHub, Zapier or hosted: which to use
| Option | What it does | Where it stops |
|---|---|---|
| Built-in payment integrations | Let clients pay invoices online. | Do not create, send or chase invoices for you. |
| By hand | Every screen of Invoice Simple, one invoice at a time. | Your evenings. |
We found no GitHub MCP server or Zapier app for Invoice Simple. To write, send and chase invoices from ChatGPT or Claude, Cotlet works in the Invoice Simple account you already have.
Invoice Simple MCP setup on GitHub and PyPI
Prefer code? Our public repo has a ready Invoice Simple MCP config for Claude Code, ChatGPT and Cursor, an agent skill and a small command-line tool. Add your Cotlet API key and your agent works in your own Invoice Simple account.
- MCP config for Claude Code, Cursor and Codex
- Agent skill and Cursor rules for Invoice Simple
- Clone it and run, Python standard library only
- Elastic License 2.0, free in your own business
- Code: https://github.com/cotlet-connect/invoice-simple-mcp
- Also listed on: Odel, mcpbeat
Who runs Cotlet
Take Group sp. z o.o. runs Cotlet. It is a software company registered in Poland, EU (VAT PL6342984273), in business since 2019, led by its founders Bart Krawczyk (Co-founder, CTO) and Jake Slugocki (Co-founder, SEO, sales and marketing). Questions about the Invoice Simple tools go to contact@cotlet.dev.
Invoice Simple MCP server: questions
How do I get access?
Sign up free at https://cotlet.dev, open Invoice Simple under Integrations in the console and sign in to Invoice Simple in its Cloud Browser. The trial starts when you sign up and asks for no card.
How do I connect Invoice Simple to ChatGPT or Claude?
Sign up at cotlet.dev, log in to Invoice Simple once in its Cloud Browser and add Cotlet to ChatGPT or Claude, following the steps in your console. No API key is needed. ChatGPT and Claude then work in your Invoice Simple account through Cotlet, in their phone apps too.
What can ChatGPT do in Invoice Simple?
With Cotlet, ChatGPT, Claude and other AI agents handle jobs like these in Invoice Simple: create invoices from job notes; chase overdue invoices; send estimates and convert the accepted ones. You ask in plain words, and anything that reaches other people waits for your OK first.
Is there an official ChatGPT or Claude app for Invoice Simple?
No. Invoice Simple has no ChatGPT or Claude connector of its own and Invoice Simple has no official MCP server (checked 8 Nov 2026). Cotlet is an independent one that works in ChatGPT, Claude, Cursor and any MCP client, on your signed-in account.
Can ChatGPT create invoices in Invoice Simple?
Yes, with Cotlet. Tell ChatGPT the client, lines and due date and it creates the invoice as a draft, then sends it after your OK.
Can ChatGPT send estimates in Invoice Simple?
Yes, with Cotlet. ChatGPT builds the estimate from your notes, sends it after your OK and turns accepted estimates into invoices.
Can ChatGPT find overdue invoices in Invoice Simple?
Yes, with Cotlet. Ask "who owes me money" and ChatGPT lists overdue invoices with the client, amount and days late.
Does Invoice Simple have an API?
No public one. Invoice Simple publishes no API keys or developer documentation (checked 8 Nov 2026). Cotlet works through your own Invoice Simple sign-in instead.
Can it charge a client's card?
No. mark_invoice_paid only records a payment you already received, such as cash or a check. Online payments stay in Invoice Simple.
Is the MCP server different from the REST API?
Only in how it is called. Both carry the same 10 tools, inputs, answers, API key and price. Agents use MCP; scripts and HTTP steps use REST.
Is Cotlet affiliated with Invoice Simple?
No. Cotlet is independent and not affiliated with Invoice Simple.
Give your AI agents your signed-in browser.
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