Invoice Generator

Invoice Generator builds an HTML invoice using React component state and exports it as a PDF through the browser's native print pipeline (window.print() with a print-only stylesheet). There's no jspdf or pdf-lib dependency — when you click Print, your browser's rendering engine takes the styled invoice block and writes it to a vector PDF, embedding fonts and preserving the exact on-screen layout.

Line items are stored in a React array and totals are recomputed on every keystroke using a single reduce() over the items array. Subtotal is the sum of (quantity × rate) per row, tax is calculated as subtotal × (taxRate ÷ 100), and the grand total adds them. All math uses standard JavaScript Number arithmetic, which is IEEE 754 double precision — accurate to about 15 significant digits, which is more than enough for invoice amounts up to nine figures.

A common gotcha with floating-point money math is that 0.1 + 0.2 doesn't equal exactly 0.3 in any IEEE 754 language. The display formats values with toFixed(2), which rounds half-to-even at the second decimal, so $0.30 will appear correctly even though the underlying number is 0.30000000000000004. For accounting systems with strict cent-perfect requirements, double-check totals against the supplier's books before sending.

Currency selection is a UI concern only — the tool stores a symbol string (USD/EUR/GBP/INR/CAD/AUD) and prepends it to formatted numbers. There is no live FX conversion; if you change currency mid-edit, the line-item rates remain numerically the same and only the symbol changes. Convert manually if you need to switch billing currency.

The print stylesheet uses CSS @media print rules to hide the form chrome, action buttons, and navigation, leaving just the invoice body on the page. Most browsers default to A4 or US Letter based on locale; you can override paper size, margins, and orientation in the print dialog. Background colors require enabling 'Background graphics' in the print options if you want the header bar to render in color.

Nothing about your invoice — client name, addresses, amounts, item descriptions — is sent to any server. The component holds state in memory and the PDF is generated client-side by your browser. Closing or refreshing the tab discards the data, so save the PDF before navigating away.

There is no logo upload, no recurring-invoice scheduler, and no payment-link integration in this version. For Stripe or PayPal links, paste the URL into the Notes field; for a logo, edit the exported PDF in Acrobat or a PDF editor afterward.