Private beta
Invoice Tiger API
Generate professional invoices from apps, automations, and AI agents.
Private beta coming soon. The Invoice Tiger API will turn structured invoice data into finished PDFs with accurate totals, through a simple REST interface. One call, one document — no template engine, no headless browser, no PDF library to keep alive.
Access is by request while the beta is small, and the developers in it shape what ships: the fields, the defaults, the edges we get right first. Tell us what you are building.
- Status
- Private beta coming soon.
- Access
- Early access by request.
- Availability
- API endpoint not yet publicly available.
Generate an invoice
One endpoint, one document. Send the invoice as JSON — who is billing, who is being billed, the line items, the tax — and get back the rendered PDF with the totals already worked out.
{
"seller": {
"name": "Acme Plumbing"
},
"customer": {
"name": "Jane Smith"
},
"invoice_number": "1042",
"issue_date": "2026-08-19",
"due_date": "2026-09-18",
"items": [
{
"description": "Water heater repair",
"quantity": 2,
"unit_price": 125
}
],
"tax_rate": 0.0875
}{
"invoice_number": "1042",
"totals": {
"subtotal": 250.00,
"tax": 21.88,
"total": 271.88
},
"pdf": "JVBERi0xLjQKJeLjz9MKMyAwIG9iago8PC9UeXBl..."
}The interface may evolve during private beta, and the endpoint is not publicly available yet.
What comes back
The generated invoice PDF, plus the totals that produced it — subtotal, tax, and the amount due. A caller that only wants the document ignores the numbers; an agent that has to say “that will be $271.88” has them without parsing the file it was just handed.
The arithmetic is not new
Rounding, per-line totals and tax on a discounted amount already have one definition, shared by the iPhone app and the free invoice generator on this site. The API is built on the same one, rather than a third opinion about what 8.75% of $250 is.
Built for agents and automation
Invoice generation is a small, well-defined job that keeps turning up inside something larger. These are the integrations the API is designed for.
AI agents
An agent that has finished a job and needs to bill for it. One call, structured data in, a finished PDF out — no browser to drive, no template to fill in, no headless renderer to keep alive.
MCP-compatible workflows
An MCP server exposing invoice generation as a tool, so an assistant can produce a real invoice inside a conversation without anyone writing an integration for it first.
SaaS products
Software that bills on someone else’s behalf — a marketplace, a booking tool, a field-service platform — and would rather not own PDF layout, pagination and rounding for the rest of its life.
Workflow automation
The step after "job marked complete" in whatever runs your operations. A webhook fires, the invoice comes back as a file, and the rest of the workflow carries it wherever it was going.
Internal tools
The billing script nobody wants to maintain. Hand it structured data and it returns a document your customers can read, instead of a spreadsheet export with your logo pasted on top.
REST and OpenAPI
A plain HTTP endpoint that takes JSON and returns a document. An OpenAPI description ships with it, so a client generator, a test harness or an agent framework can read the interface rather than be told about it.
Designed for ephemeral processing
The API is being designed to process invoice data only long enough to fulfil the request and return the generated document, without retaining invoice content afterward. Final data-handling terms will be documented before the API opens.
The existing web invoice generator is unaffected: it remains entirely browser-local and does not send invoice contents or logos to Invoice Tiger. Invoice Tiger on iPhone keeps your records on the phone, as it always has.
Early access
Request API access
Four fields, one of them required. Tell us what you are building, and we will be in touch when the beta opens.
Or email [email protected] and say the same thing in your own words. The form does nothing the address does not — it opens a message in your mail app with the fields filled in.
What you write goes to us by email and nowhere else. We count that a request was sent and which kind of use case was picked; your address, your company and your answer are not part of that count. Same rules as the rest of the site — see the privacy policy.
Need an invoice today, not an endpoint?
The free invoice generator makes one in your browser right now, and Invoice Tiger on iPhone is the version that remembers your customers. Questions about any of this go to support.