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Build with AI
Three ways to use AI with Free Invoice Automation. Your own assistant through MCP, our built-in invoice agent, and docs written for AI tools.
Free Invoice Automation was built so that an AI assistant can do your invoicing as safely as you can. You can connect the assistant you already use (Claude, ChatGPT, Grok, Gemini CLI and others) to our MCP server, use the AI invoice agent inside the web app, or point any AI tool at these docs in plain Markdown. All three use the same actions, with the same permissions, as the web app and the REST API.
Choose how you want to work
| You want to | Use | AI key needed | Credits used |
|---|---|---|---|
| Ask Claude, ChatGPT, Grok or another assistant to create and send invoices | MCP server | No: your assistant does the AI work | No |
| Describe an invoice in plain words inside the app, or run it on a schedule | AI invoice agent | No: it runs on our key, or yours if you prefer | Yes, unless you use your own key |
| Give an AI tool accurate answers about the product and API | Docs for AI | No | No |
| Write your own integration with an AI framework | REST API | Your choice | No |
MCP server
Connect your assistant with a browser sign-in. No setup, no AI key.
AI invoice agent
Plain-language drafts and automations inside the dashboard.
Docs for AI
llms.txt, the full docs in one file, and every page as Markdown.
Connect your AI assistant
The quickest start is the MCP server. Pick your client below, sign in when your browser opens, and approve the account and scopes.
Connect your AI assistant
Sign in via browser. No AI key needed.
Add a custom connector in Claude, or run the command below in Claude Code.
Open Claude connectorsclaude mcp add --transport http freeinvoiceautomation https://mcp.freeinvoiceautomation.com/mcpThen enter /mcp in Claude Code and confirm freeinvoiceautomation is connected.
Using another MCP client? Point it at:
https://mcp.freeinvoiceautomation.com/mcpOnce connected, try a request like this:
Create a draft invoice for Acme Ltd for 10 hours of design work at 50 USD an hour, due in 14 days. Show me the preview before sending.Your assistant calls list_clients to find Acme, create_invoice to make the draft, and preview_send to show you what the email will look like. Nothing is sent until you confirm. See the tool reference for every tool.
One capability, every surface
Every action in Free Invoice Automation is defined once, with its input, its output, a permission key and a hint that says whether it only reads, writes, or is destructive. The web app, the REST API, the MCP server, the CLI, the store connectors and the AI agent are all built from that same definition. In practice this means:
- The same rules everywhere. An MCP tool cannot do anything the matching API endpoint cannot do, and the API cannot do anything your role does not allow.
- The same data everywhere. An invoice created by your assistant shows up in the app at once, with the same number sequence, totals and statuses.
- No feature is app-only. If you can click it, there is an API route for it. Only some actions are exposed as MCP tools (28 in total, listed in the tool reference); the others are available through the API, the CLI and the agent.
Safe by default
AI tools make mistakes and can be misled by text they read, such as a pasted email that says "send this now". We designed every AI surface around that:
- Drafts first. Assistants and the agent create drafts. Sending a document needs
confirm: trueon the call, unless you deliberately created a token or key withauto_sendmode. - Confirmation for destructive actions. Voiding an invoice or issuing a credit note always needs
confirm: true. Without it you get a preview of what would happen and the errorconfirmation_required. - Your permissions, never more. An MCP token or API key holds only the scopes you chose, and at every call it is limited to what your role allows right now. If your role loses a permission, your tokens lose it on the next request.
- Everything is audited. Every write records who did it, including whether it was you in the app, an API key, an MCP client or the agent.
Read Drafts and confirmations for the details.
The AI invoice agent
The agent lives in Automate > AI agent in the web app. Type "Invoice Acme for 10 hours of design at $50" or paste an email, and it creates the client if needed and a draft invoice for you to check. You can also set up automations that run on a schedule or when something happens, such as "when a Stripe payment arrives, make the receipt".
The agent runs on our own AI key, so you do not need one. Each run uses credits:
- Free: 250 welcome credits in your first month after sign-up, unlocked by adding a card (a $0 verification; the card is never charged).
- Team: 1,000 credits a month, and 2,000 in your first paid month.
- Credit packs: 1,000 credits for $5 on any plan, bought only when you click to buy.
- Your own key: connect an Anthropic, OpenAI, Google or OpenAI-compatible key and the agent uses no credits at all. See Use your own AI key.
The MCP server never uses credits. When you work through Claude or ChatGPT, your own assistant does the AI work and our server only runs the actions it asks for.
Docs for AI tools
Every page of these docs is available as plain Markdown, and the whole site is indexed in /llms.txt with the full text in /llms-full.txt. Use the Copy page menu at the top of any page to copy it or open it in ChatGPT or Claude. See Docs for AI.
What you need
- A Free Invoice Automation account. Sign up with email and password, Google or a magic link.
- For MCP: an MCP-capable client. No AI key is needed.
- For the agent: credits or your own AI key, and the
ai.usepermission on your role. - For the API: an API key from Settings > API keys.
The MCP server, the agent and the API all ship at launch on 1 January 2027. Some tools arrive later with their features; each one shows its release in the tool reference.