Authentication

All API requests must include a valid API key in the Authorization header.

API key format

API keys use the prefix oim_ followed by 64 hexadecimal characters:

oim_a1b2c3d4e5f67890abcdef1234567890abcdef1234567890abcdef12345678

Using your API key

Include your key in every request as a Bearer token:

curl -X GET https://onlineinvoicemaker.com/api/v1/invoices \
  -H "Authorization: Bearer oim_your_api_key_here"

Keep your API key secret

Your API key grants access to your business data. Never share it in client-side code, public repositories, or logs. If a key is compromised, revoke it immediately from the dashboard.

Creating an API key

1. Navigate to Integrations > API Keys in your dashboard
2. Click Create API Key
3. Give it a descriptive name (e.g., "Zapier Integration")
4. Select the appropriate scope
5. Copy the key immediately — you will not be able to see it again

Scopes

Each API key has a scope that determines its permissions:

Scope	Read	Write	Webhooks	Description
all	Yes	Yes	Yes	Full access to all resources
read	Yes	No	No	Read-only access to invoices, quotations, customers
write	Yes	Yes	No	Read and write access to resources
webhooks	No	No	Yes	Manage webhook subscriptions only

Key management

Listing keys

View all your API keys in the dashboard. For security, only the first 12 characters of each key are shown (the prefix).

Revoking keys

Revoked keys stop working immediately. This action cannot be undone.

Expiration

You can optionally set an expiration date when creating a key. Expired keys automatically stop working.

Plan limits

Plan	Max API Keys
Basic	2
Pro	20

Error responses

Status	Description
401	Missing or invalid Authorization header
401	API key not found, revoked, or expired
403	Key does not have the required scope for this endpoint
429	API key limit reached for your plan

Example error:

{
  "error": "Invalid API key"
}

Code examples

Node.js

const response = await fetch('https://onlineinvoicemaker.com/api/v1/invoices', {
  headers: {
    'Authorization': 'Bearer oim_your_api_key_here',
    'Content-Type': 'application/json',
  },
});

const data = await response.json();

Python

import requests

headers = {
    'Authorization': 'Bearer oim_your_api_key_here',
    'Content-Type': 'application/json',
}

response = requests.get(
    'https://onlineinvoicemaker.com/api/v1/invoices',
    headers=headers,
)

data = response.json()

PHP

$ch = curl_init('https://onlineinvoicemaker.com/api/v1/invoices');
curl_setopt($ch, CURLOPT_HTTPHEADER, [
    'Authorization: Bearer oim_your_api_key_here',
    'Content-Type: application/json',
]);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

$response = curl_exec($ch);
$data = json_decode($response, true);