Quickstart: Create Your First Invoice with Invoice AI

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.

You’ll go from zero to a sent invoice and a working API call in five steps. No prior setup is required — you can start as a guest and add an account at any point along the way.

1. Open the app and sign in

   Go to https://invoice.horizonpay.co.

   You have two ways to get started:

   • Start immediately as a guest — Click Create an invoice on the landing page. Invoice AI signs you in anonymously, no email required. Your data is kept for 30 days.
   • Create a full account — Click Create account, enter your name, email, and a password of at least 8 characters, then confirm your email address from the link Invoice AI sends you.

   Guest mode is the fastest path to your first invoice. You can add an email and password later to make your account permanent — all your invoices transfer automatically.

2. Set up your business profile

   If you signed up with an account, the onboarding wizard opens automatically. Complete the two steps:

   Step 1 — Business details

   Invoice AI pre-selects your country from your IP address. You can change it at any time. Fill in:

   Field	Required?
   Business name	Yes
   Country	Yes
   Currency	Yes (follows the country you pick)
   Address	Yes
   Tax ID (VAT, EIN, GST, ABN, etc.)	Optional

   Step 2 — Payment details

   Add your bank account name, account number, and routing code so your clients see how to pay at the bottom of every invoice. This step is skippable — you can fill it in later under Settings → Business.

   If you started as a guest, Invoice AI lets you fill in your business details directly in the invoice builder the first time you create an invoice. The onboarding wizard only appears for email-based accounts.

3. Create your first invoice

   From the dashboard, click New invoice (or navigate to Invoices → New).

   1. Add a client — Type your client’s name. You can also add their email, address, and tax ID.
   2. Set the invoice date and due date — Invoice AI defaults to today’s date.
   3. Add line items — For each item, enter a description, quantity, and rate. Add a tax rate per line if applicable — Invoice AI calculates the split automatically.
   4. Review the totals — The live preview updates as you type. Check the subtotal, tax amount, and grand total.
   5. Save or send — Click Save draft to keep editing later, or Finalize & send to assign an invoice number and share it with your client.

   Click Use AI above the form to describe your invoice in plain language — for example, “Invoice Acme Corp $12,000 for UX design, 18% tax”. Review the AI-generated summary, then click Fill this in to populate the form. Nothing is saved until you confirm.

   Once finalized, Invoice AI assigns the next sequential invoice number and gives you a shareable link and a PDF download. Send the link directly to your client or email it from within the app.

4. Generate an API key

   API keys let you automate invoice creation, sync client data, and build integrations — all without touching the UI.

   1. Go to Settings → API Keys.
   2. Click New API key.
   3. Give the key a name (for example, “Zapier integration” or “billing script”).
   4. Select the scopes your integration needs:

   Scope	What it grants
   invoices:read	List and read invoices, including PDFs
   invoices:write	Create, edit, and delete drafts
   invoices:finalize	Finalize invoices and void them
   invoices:send	Email invoices to clients
   clients:read	List and read clients
   clients:write	Create, update, and archive clients
   products:read	List and read products and prices
   products:write	Create, update, and archive products and prices
   payments:write	Mark invoices as paid
   webhooks:manage	Manage webhook endpoints

   5. Click Create. Copy the key — it starts with inv_live_ and is shown only once.

   Store your API key securely. Invoice AI never displays the full key again after creation. If you lose it, revoke it and create a new one. A leaked key cannot create additional keys — key management is only possible in the UI.

   Guest accounts cannot hold API keys. If you see a message prompting you to add an email and password, follow the steps in Account Setup → Claiming a guest account first.

5. Make your first API call

   With your key in hand, make a request to the invoices endpoint to confirm everything is working.

   curl https://invoice.horizonpay.co/api/v1/invoices \
     -H "Authorization: Bearer inv_live_..."
   

   A successful response returns a { data } envelope containing your invoice list:

   {
     "data": [
       {
         "id": "in_01abc...",
         "status": "open",
         "amount_due": 1440000,
         "currency": "USD",
         "customer": "cus_01xyz...",
         "created": "2025-06-15"
       }
     ],
     "next_cursor": null
   }
   

   All monetary values are integer minor units. In the example above, 1440000 is $14,400.00. Divide by 100 to get the major-currency amount.

   You can filter results with query parameters:

   # Filter by status
   curl "https://invoice.horizonpay.co/api/v1/invoices?status=open" \
     -H "Authorization: Bearer inv_live_..."
   
   # Filter by date range
   curl "https://invoice.horizonpay.co/api/v1/invoices?from=2025-01-01&to=2025-06-30" \
     -H "Authorization: Bearer inv_live_..."
   
   # Paginate using a cursor from the previous response
   curl "https://invoice.horizonpay.co/api/v1/invoices?cursor=<next_cursor>" \
     -H "Authorization: Bearer inv_live_..."
   

   Available status filters: draft, open, paid, overdue, void.

What’s next

API Reference

Explore all endpoints: invoices, customers, products, prices, and webhooks — with full request and response schemas.

Account Setup

Learn how to claim a guest account, reset your password, and complete the onboarding wizard.