# easy-e-invoice
> Create ZUGFeRD and XRechnung compliant e-invoices directly in your browser. No registration, no subscription, no server-side data storage.

## Application Overview

easy-e-invoice is a **client-side web application** that provides a WYSIWYG editor for creating electronic invoices (ZUGFeRD 2.3, XRechnung, EN-16931 compliant). Built entirely as a local-first progressive web application — all data processing happens in the browser, no data is sent to external servers.

## Tech Stack

- **Framework:** Next.js 16 (App Router)
- **Language:** TypeScript (strict mode)
- **Styling:** Tailwind CSS v4
- **State Management:** Zustand (client-side stores)
- **Internationalization:** next-intl (de, en)
- **PDF Generation:** Client-side (pdf-lib, pako, puppeteer for server-side rendering)
- **XML Processing:** fast-xml-parser, xml2js
- **Parsing:** pdf-parse for PDF data extraction
- **Validation:** Zod-based invoice data validation (AI SDK)
- **Payment:** Stripe Checkout (optional usage-based pricing)

## Core Capabilities

### Invoice Creation
- WYSIWYG editor with live preview
- Fill standard and custom invoice fields
- Add/remove line items with descriptions, quantities, unit prices
- Support for discounts, tax rates (standard, reduced, §19 UStG small business exemption)
- Unlimited invoice line items

### Supported Formats
- **ZUGFeRD 2.3** (hybrid PDF/A-3 with embedded XML)
- **XRechnung** (pure XML according to EN-16931, CII profile)
- **Standard PDF** (human-readable invoice PDF)
- All outputs are EN-16931-compliant electronic invoices

### WYSIWYG Editing
- Direct inline editing of invoice preview
- Real-time recalculation of totals (net, tax, gross)
- Auto-formatting for German number and decimal conventions
- Live preview updates on every keystroke

### Keyboard-First Workflow
- Full keyboard navigation through all form fields
- Tab-order optimized for invoice data entry
- Keyboard-driven dropdowns and selection controls
- Export dialogs completable without mouse
- ARIA labels and semantic HTML for screen reader compatibility
- Visible focus indicators for all interactive elements

### Theme Customization
- Pre-built theme presets (modern, classic, minimal)
- Light and dark mode for each theme
- Custom company logo upload (positioning and sizing)
- Font family and size selection (Inter, DM Sans, PT Sans, Comic Neue)
- Primary and accent color customization for headers, borders, and accents
- Background color and pattern selection
- All themes optimized for both screen display and PDF export

### PDF Upload & Reuse
- Upload existing invoices as PDF to edit and re-export
- Upload existing ZUGFeRD files to re-import the structured data
- Upload existing XRechnung XML to re-import data
- Extract invoice data from uploaded PDF documents

### Data Privacy & Local-First
- 100% client-side processing — no data sent to servers
- Invoice data stored only in browser memory / localStorage
- No account or registration required
- No cookies or tracking
- No persistent storage on any server
- Session-based auto-save for recovery

### Accessibility
- Keyboard-navigable interface
- Screen reader optimized with ARIA labels
- Semantic HTML heading hierarchy
- Focus management with visible indicators
- High contrast mode support via Tailwind dark mode

### Usage & Pricing
- Free to use (create and export up to basic limit)
- Usage-based pricing (pay only when you export beyond free tier via Stripe)
- No recurring subscription commitment
- No software installation required

## Input Formats
- Manual form entry (keyboard)
- PDF upload for data extraction
- ZUGFeRD PDF upload for re-import
- XRechnung XML upload for re-import

## Output Formats
- ZUGFeRD 2.3 PDF (hybrid PDF/A-3 with embedded XML)
- XRechnung XML (EN-16931 CII)
- Standard PDF invoice
- Print via browser print dialog

## SEO & Discoverability
- Structured Data: JSON-LD (SoftwareApplication, WebPage, Organization)
- Open Graph protocol meta tags
- Hreflang for de/en locale targeting
- XML Sitemap for all route variants
- Semantic HTML5 structure (article, section, nav, header, footer)
- Progressive enhancement and graceful degradation

## Internationalization
- German (de-DE) — primary language
- English (en-US)
- German-specific legal requirements supported (§19 UStG, §14 UStG)
- Number formatting and date conventions per locale

## Contact
- Website: https://easy-e-invoice.online
- Legal entity: Jan Wagner, Egerlandstraße 38, 85368 Moosburg, Germany
- Email: info@easy-e-invoice.online