# Invoice AI

- [Invoice AI: Professional Invoicing for Freelancers](https://docs.horizonpay.co/introduction.md): Invoice AI helps freelancers and small businesses create professional invoices, handle tax, generate PDFs, and get paid — with or without an account.
- [Quickstart: Create Your First Invoice with Invoice AI](https://docs.horizonpay.co/quickstart.md): Set up your business profile, create your first invoice in the UI, generate a scoped API key, and list invoices via the REST API — all in under 10 minutes.
- [Invoice AI: Account Setup, Guest Mode & Onboarding](https://docs.horizonpay.co/account-setup.md): Create an account with email, use guest mode with no signup, complete the onboarding wizard, claim a guest account, and reset your password.
- [Invoices: Lifecycle, Status Transitions and Numbering](https://docs.horizonpay.co/concepts/invoices.md): Learn how Invoice AI models invoices: status lifecycle, number assignment, frozen snapshots, and how every amount is represented in the API.
- [Customers — Fields, Archiving and Invoice Snapshots](https://docs.horizonpay.co/concepts/customers.md): Understand how Invoice AI models customers: the fields on a customer record, how archiving works, and how customers link to invoices.
- [Products & Prices — Catalog Model and Invoice Lines](https://docs.horizonpay.co/concepts/products-and-prices.md): Learn how Invoice AI's product catalog works: products, one-time and recurring prices, and how to attach catalog items to invoice line items.
- [Create Invoices with the AI Assistant](https://docs.horizonpay.co/features/ai-invoice-creation.md): Use the Invoice AI assistant to generate invoices from plain text or voice — just describe what you're billing for and confirm the result.
- [Invoice Lifecycle: Draft to Paid or Void](https://docs.horizonpay.co/features/invoice-lifecycle.md): Understand every invoice status — draft, open, overdue, paid, and void — and how to move between them in the UI or via the API.
- [Download PDF and Share Invoice Links](https://docs.horizonpay.co/features/pdf-and-sharing.md): Download a professional PDF of any finalized invoice or share a secure public link your client can open without logging in.
- [Email Invoices Directly to Clients](https://docs.horizonpay.co/features/emailing-invoices.md): Send finalized invoices straight to your client's inbox with one click — includes a link to the shareable invoice page and PDF download.
- [Business Profile, Address & Invoice Numbering — Invoice AI](https://docs.horizonpay.co/settings/business-profile.md): Configure your legal name, address, tax ID, currency, payment details, and invoice numbering so every invoice reflects your business accurately.
- [API Keys — Create, Scope, and Revoke Tokens — Invoice AI](https://docs.horizonpay.co/settings/api-keys.md): Create scoped API keys to integrate Invoice AI with your apps and automations, understand available permissions, and keep credentials secure.
- [Webhook Endpoints — Real-Time Invoice Notifications](https://docs.horizonpay.co/settings/webhooks.md): Set up HTTPS endpoints to receive real-time invoice events, verify delivery signatures, and automate workflows when invoices are created, paid, or voided.
- [Invoice AI REST API: Base URL, Amounts & Responses](https://docs.horizonpay.co/api-reference/overview.md): Base URL, versioning, request format, the { data } response envelope, resource ID prefixes, and amount conventions for the Invoice AI REST API.
- [Invoice AI API Authentication: API Keys and Scopes](https://docs.horizonpay.co/api-reference/authentication.md): Create Invoice AI API keys in Settings, pass them as Bearer tokens on each request, and assign scopes to restrict what each key can do.
- [Invoice AI API Errors: Status Codes & Problem+JSON](https://docs.horizonpay.co/api-reference/errors.md): HTTP status codes, the application/problem+json error envelope, error type slugs, and best practices for handling errors in your integration.
- [Invoice AI API Pagination: Cursor-Based List Pages](https://docs.horizonpay.co/api-reference/pagination.md): How cursor-based pagination works on Invoice AI list endpoints, the cursor and limit parameters, and iterating all pages safely in JavaScript.
- [List All Invoices — Invoice AI REST API Reference](https://docs.horizonpay.co/api-reference/invoices/list.md): Retrieve a cursor-paginated list of invoices. Filter by status, customer, or date range. Results include overdue detection and pagination cursors.
- [Create a New Draft Invoice — Invoice AI REST API](https://docs.horizonpay.co/api-reference/invoices/create.md): Create a new draft invoice with line items. Drafts have no invoice number and can be freely edited or deleted before you finalize them.
- [Retrieve Invoice Details — Invoice AI API Reference](https://docs.horizonpay.co/api-reference/invoices/retrieve.md): Fetch a single invoice by its public ID or UUID, including the complete list of line items with per-line amounts and tax breakdowns.
- [Update a Draft Invoice — Invoice AI API Reference](https://docs.horizonpay.co/api-reference/invoices/update.md): Partially update a draft invoice's header fields and line items. Only draft invoices can be modified; sending PATCH to a finalized invoice returns 409.
- [Finalize a Draft Invoice — Invoice AI API Reference](https://docs.horizonpay.co/api-reference/invoices/finalize.md): Finalize a draft invoice: assigns a permanent consecutive invoice number, moves status to open, and freezes business and customer snapshots.
- [Mark an Invoice as Paid — Invoice AI API Reference](https://docs.horizonpay.co/api-reference/invoices/pay.md): Record an out-of-band payment against an open or overdue invoice, setting its status to paid and triggering the invoice.paid webhook event.
- [Void an Invoice (Open/Overdue) — Invoice AI REST API](https://docs.horizonpay.co/api-reference/invoices/void.md): Cancel an open or overdue invoice while keeping its number in the audit trail. Optionally provide a reason; the void is permanent and irreversible.
- [Customers API — List, Create, Retrieve, Update, Delete](https://docs.horizonpay.co/api-reference/customers/overview.md): Manage the customers you bill. Create, update, and archive customer records. All amounts on related invoices use integer minor units.
- [Products API — List, Create, Retrieve, Update, Delete](https://docs.horizonpay.co/api-reference/products/overview.md): Manage your product catalog in Invoice AI. Products group one or more prices and appear as selectable line items when creating invoices.
- [Prices API — List, Create, Retrieve, Update, Archive](https://docs.horizonpay.co/api-reference/prices/overview.md): Define one-time or recurring prices for products in your catalog. All amounts are integers in minor currency units (e.g. 5000 = $50.00).
- [Invoice Items API — List, Create, Retrieve, and Delete](https://docs.horizonpay.co/api-reference/invoice-items/overview.md): Add and remove line items on draft invoices. Reference a catalog price or supply a custom description and unit amount. All amounts are integer minor units.
- [Webhook Endpoints API — Manage & Receive Event Deliveries](https://docs.horizonpay.co/api-reference/webhooks/overview.md): Register HTTPS endpoints to receive real-time Invoice AI events. Deliveries are signed with Standard Webhooks HMAC-SHA256 and retried on failure.
- [Invoice AI Webhook Event Types and Payload Reference](https://docs.horizonpay.co/api-reference/webhooks/events.md): Complete reference for all Invoice AI webhook event types, payload shapes, signature verification, and handling examples for invoice lifecycle events.