API Usage Guide

This guide contains important information about using the Invoiless API effectively.

HTTP Methods

PUT vs PATCH

When updating resources (invoices, customers, etc.), you can use either PUT or PATCH:

• PUT - Replaces the entire resource with the provided data

  • All fields in the request body will replace the existing resource
  • Any fields not included will be removed or reset to defaults

• PATCH - Updates only the fields you provide

  • Only the fields in the request body will be updated
  • Fields not included in the request remain unchanged

Removing Field Values

To remove or clear a field value when updating a resource, pass either:

• An empty string ""
• null

Example:

{
  "notes": "",
  "terms": null
}

Rate Limiting

API rate limits are enforced per API key. Contact support if you need higher limits for your use case.

Best Practices

1. Use HTTPS only - All API requests must use HTTPS. HTTP requests will be rejected.
2. Store your API key securely - Never expose your API key in client-side code or public repositories.
3. Use PATCH for partial updates - When updating a few fields, use PATCH instead of PUT to avoid accidentally removing data.
4. Handle errors gracefully - Always check response codes and handle errors appropriately.
5. Use pagination - When fetching lists of resources, use the page and limit parameters to manage large result sets.