# Giltiq
> VAT validation and e-invoicing API for the German-speaking market. BZSt qualified confirmations, VIES failover, XRechnung/ZUGFeRD generation.

## API Reference
- [Auth Endpoints](https://giltiq.de/en/reference/auth/): Registration and API key authentication for the Giltiq API.
- [Error Handling](https://giltiq.de/en/reference/errors/): Error codes and response format.
- [Qualified Confirmations Endpoints](https://giltiq.de/en/reference/qualified-confirmations/): Retrieve stored §18e UStG qualified confirmation receipts.
- [Status Endpoint](https://giltiq.de/en/reference/status/): Check upstream VAT source availability and failover state.
- [Usage Endpoint](https://giltiq.de/en/reference/usage/): Monitor your API consumption via response headers or the usage endpoint.
- [Validate Endpoint](https://giltiq.de/en/reference/validate/): Validate EU VAT IDs.

## Guides
- [Authentication](https://giltiq.de/en/guides/authentication/): How authentication works in Giltiq — tiers, API keys, and usage headers.
- [Qualified Confirmation (§18e UStG)](https://giltiq.de/en/guides/qualified-confirmation/): How to use Giltiq for §18e UStG audit compliance in German cross-border B2B invoicing.
- [Quickstart](https://giltiq.de/en/guides/quickstart/): Get started with Giltiq in under 5 minutes.

## Documentation
- [Combined docs](https://giltiq.de/llms-full.txt): Single-file Markdown export of all documentation

## Agent Integration
- [Agent Card](https://giltiq.de/agent-card.md): Copy-paste product card for system prompts, TOOLS.md, or MCP registries