API Reference

For developers integrating InvoiceDLT into their own systems. Not what you're looking for? View the User Help Center →

Authentication

InvoiceDLT supports two auth methods:

Session cookie — used by the web app automatically after login. No setup required.
API key bearer token — for server-to-server calls. Pass as Authorization: Bearer idlt_live_... header.

Generate API keys from Settings → API Keys inside the app. Keep them secret — treat them like passwords.

Endpoint Reference

Base URL: https://api.invoicedlt.com

Method	Endpoint	Description
POST	/api/auth/register	Create a new account.
POST	/api/auth/login	Log in, returns session token.
POST	/api/auth/logout	Invalidate session.
GET	/api/invoices	List all invoices (paginated).
POST	/api/invoices	Create a new invoice.
GET	/api/invoices/:id	Get invoice details.
PATCH	/api/invoices/:id	Update invoice fields.
DELETE	/api/invoices/:id	Delete (void) invoice.
POST	/api/invoices/:id/send	Email invoice to client.
POST	/api/invoices/:id/remind	Send payment reminder.
POST	/api/invoices/:id/mark-paid	Mark invoice as paid manually.
GET	/api/invoices/:id/pdf	Printable invoice page (HTML, suitable for puppeteer PDF).
GET	/api/clients	List all clients.
POST	/api/clients	Create a client.
GET	/api/clients/:id	Get client details.
PATCH	/api/clients/:id	Update client.
DELETE	/api/clients/:id	Delete client.
POST	/api/keys	Generate a new API key.
GET	/api/keys	List API keys (values masked).
DELETE	/api/keys/:id	Revoke API key.
POST	/api/webhooks	Register a webhook endpoint.
GET	/api/webhooks	List webhooks.
DELETE	/api/webhooks/:id	Delete webhook.
POST	/api/billing/subscribe	Create Stripe checkout session for subscription.
GET	/api/billing/portal	Get Stripe billing portal URL.

Webhooks

Available Events

invoice.created
invoice.sent
invoice.viewed
invoice.paid
invoice.overdue
invoice.voided

Verifying Webhook Signatures

Every webhook request includes an X-InvoiceDLT-Signature header. Verify it with HMAC-SHA256:

// Node.js
const crypto = require('crypto');
const sig = req.headers['x-invoicedlt-signature'];
const expected = crypto
  .createHmac('sha256', process.env.WEBHOOK_SECRET)
  .update(rawBody)
  .digest('hex');
if (sig !== expected) return res.status(401).send('Invalid signature');

XRPL Payment Verification

For XRPL-based invoice payments:

Client scans QR code and sends XRP from their wallet.
Submit the XRPL transaction hash to: POST /api/invoices/:id/verify-payment with body {"txHash": "..."}
InvoiceDLT validates the transaction on-chain and marks the invoice paid if amount and destination match.

The public payment page (/pay/:id) handles this automatically — manual verification is only needed for custom integrations.

Rate Limits

Plan	Requests / minute	Invoices / month	Clients
Solo (Free)	30	10	3
Pro	120	Unlimited	50
Business	600	Unlimited	Unlimited

Rate limit responses return HTTP 429 with header Retry-After: N (seconds until reset).

Error Codes

HTTP Status	Meaning
400	Bad Request — missing or invalid fields. Check the `error` field in the response.
401	Unauthorized — missing or invalid API key / session.
403	Forbidden — your plan doesn't include this feature.
404	Not Found — the invoice or client ID doesn't exist.
409	Conflict — e.g., invoice already paid, or email already registered.
429	Rate limit exceeded. Wait for the `Retry-After` period.
500	Server error. Retry after a moment; contact support if it persists.

Code Examples

Create an Invoice (curl)

curl -X POST https://api.invoicedlt.com/api/invoices \
  -H "Authorization: Bearer idlt_live_YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "clientId": 42,
    "dueDate": "2026-04-01",
    "currency": "USD",
    "items": [
      { "description": "Web design", "qty": 1, "unitPrice": 1500 }
    ],
    "notes": "Please pay via the link below."
  }'

List Invoices (JavaScript)

const res = await fetch('https://api.invoicedlt.com/api/invoices', {
  headers: { Authorization: 'Bearer idlt_live_YOUR_KEY' }
});
const { invoices } = await res.json();
console.log(invoices);

Register a Webhook (Python)

import requests
requests.post(
  'https://api.invoicedlt.com/api/webhooks',
  headers={'Authorization': 'Bearer idlt_live_YOUR_KEY'},
  json={'url': 'https://myapp.com/hooks/invoicedlt', 'events': ['invoice.paid']}
)