Invoices and credit notes
Render the document from the same template and data your billing screen uses, at the moment you issue it.
Invoices your billing system already knows how to draw
Send the invoice HTML your application renders and get back the PDF you send the customer. Correct page numbers, the paper size their country expects, a whole billing run in one submission, and the archived copy in storage you own.
Create a free accountRead the API docs
- 100 free PDFs each month
- Batched billing runs
- Delivered to your own S3
- UK-operated infrastructure
INV-1042Issued 29 August 2026
A4Hosting, August720.00
Additional sites45.00
Support retainer180.00
VAT at 20%189.00
Total due1,134.00
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The billing run
The hard part is not drawing one invoice
Rendering a single invoice is a solved problem in any language. What breaks is the rest of it: four thousand documents on the first of the month, a layout that paginates differently once a customer has thirty line items, an archive somebody will ask you to produce in five years, and a download link that does not stream every byte through your application.
Ironfang Render takes the HTML you already render and handles the run around it. Submit the cycle as a batch, take a webhook per document, deliver each one into your own bucket, and let the customer download it from there.
POST /render/v1/pdf
Authorization: Bearer if_live_...
Content-Type: application/json
{
"html": "<html>...invoice INV-1042...</html>",
"paper_format": "a4",
"print_background": true,
"margin": { "top": 0.6, "bottom": 0.8 },
"header_html": "<span></span>",
"footer_html": "<p style='font-size:9px'>Page <span class='pageNumber'></span></p>"
}
200 OK
Content-Type: application/pdfCapabilities
What an invoice needs that a print button does not
Pagination, paper size, volume, custody and delivery: the five things that turn one document into a billing process.
One invoice template
The markup your billing screen renders is the markup that prints. No second layout in a drawing API, and no way for the on-screen invoice and the attached one to disagree. Or store it once as a document template and send only the data, checked against its schema and printed from a published, numbered revision.
Page numbers that are correct
Footer templates carry Chrome's pageNumber and totalPages, so a five-page invoice numbers itself rather than being counted by your code before it knows how it paginates.
A4 or Letter, per request
Six paper sizes with per-side margins and a scale factor, so the same template serves a UK customer on A4 and a US one on Letter without a branch in your code.
A month end in one submission
Submit the month as batches and asynchronous jobs instead of holding a connection open for each document, with a webhook when each one is ready.
Archived where you keep records
Deliver straight to your own S3-compatible storage, so the copy you must keep for seven years sits in a bucket under your retention and access rules.
Customer downloads, unproxied
Deliver to your own bucket and hand out links under your own rules, or pass on a finished job's signed result link, valid for 15 minutes, without streaming the bytes or exposing a key.
Use cases
Documents a billing system sends
Anything your application already renders on screen and somebody expects to arrive as a file.
Monthly billing runs
Submit the whole cycle as a batch overnight and take a webhook as each document lands in your bucket.
Statements and remittances
Period statements and remittance advice from the same pipeline, with the paper size the recipient expects.
Receipts and order confirmations
Attach a printable copy to the email your application already sends, produced from one request.
Purchase orders and quotes
Outbound documents that need to look like the rest of your brand, without a word processor template nobody owns.
Self-serve invoice history
Keep each issued PDF in your own bucket, so a customer downloads any past invoice from their account without a support request.
Other documents, and the code to start with
Invoices are one shape of a wider capability. The same endpoint prints statements, contracts, reports and certificates from the same markup you already maintain. The guide has a complete invoice template to download, a multipage version, the request that renders them and the PDFs they produce.
Pricing
Priced per invoice, not per page
Each invoice PDF counts once, every page up to 100 included; a longer document is refused and counts nothing. A failed render counts nothing, and a batch that cannot be admitted in full is refused before any invoice renders. Every account has a free allowance each month, with no card required. Past it, Pay as you go charges the rates below, within the monthly usage limit you set. Prices exclude VAT.
PDFs
Each PDF returned or stored, every page within the page limit included.
100 PDFs free each month
| Paid units after the free allowance | Rate per 1,000 |
|---|---|
| First 10,000 | £1.50 |
| Next 90,000 | £0.70 |
| Next 900,000 | £0.50 |
| Above 1,000,000 | £0.40 |
Questions
Before you integrate
The details that decide whether this fits, without reading the whole reference first.
- Do I have to rebuild my invoice layout?
- No. Send the HTML your billing screen already renders. It is printed in a real browser, so the document the customer receives is the document you can see in your own application.
- How do I get page numbers on a multi-page invoice?
- Supply footer HTML using Chrome's pageNumber and totalPages classes and it repeats on every sheet. Header and footer templates render in their own context and inherit nothing from the page, so set their font and size inside the template.
- Can I generate a whole month of invoices at once?
- Yes. Submit them as a batch and poll the batch for progress, or send them as asynchronous jobs and take a webhook per document. Neither path holds a connection open while thousands of PDFs render.
- Where does the finished PDF go?
- Back in the response for a single document, or straight into your own S3-compatible storage when you configure a delivery destination. The archived copy then lives in the bucket your retention policy already covers.
- How do I let a customer download their invoice?
- Deliver each PDF to your own S3-compatible bucket and give the customer a link from there, under the expiry and access rules you already use. For an immediate download, a finished asynchronous job also returns a signed result link that works without an API key for 15 minutes.
- What does an invoice cost to generate?
- Each PDF counts once against the PDF meter, every page up to 100 included, and a failed render counts nothing. Every PDF request renders the document afresh, so keep the copy you issue and serve repeat downloads from it rather than rendering the invoice again. The free allowance and the rates are under Pricing on this page.
- Are the totals and the numbering handled for me?
- No, and they should not be. Your billing system owns the invoice number, the tax treatment and the totals. Ironfang Render renders the document your system produced, which is what keeps the PDF and your ledger in agreement.
- Do you output PDF/A or a structured e-invoicing format?
- No. The output is a standard PDF. PDF/A archival profiles and the structured formats such as Factur-X, ZUGFeRD and PEPPOL are not produced, so if a customer or a tax authority requires one, you will need a step that emits it.
Less to operate. More to ship.
Render your next invoice
Create an account, take a key and post the HTML your billing screen already produces. Every account has free PDFs each month.
100 free PDFs each month, no card required, and no charge for failed renders.