bexio API: The Complete 2026 Guide for Swiss Freelancers

What Is the bexio API?

An API (Application Programming Interface) lets different software systems exchange data automatically. The bexio API is a RESTful interface that exposes bexio's core features—contacts, invoices, accounting, inventory—to external applications.

In practical terms: Instead of manually creating an invoice in bexio after completing a project, your project management tool can trigger automatic invoice creation. Instead of copying customer details from your webshop, orders flow directly into bexio.

The API uses HTTPS and JSON format, making it compatible with any programming language. bexio currently offers API version 3.0.0.

What You Can Automate

Popular Zapier Automations for Freelancers

1. Shopify → bexio: New order creates invoice automatically
2. Toggl → bexio: Logged time entries sync to project
3. HubSpot → bexio: New CRM contact creates bexio contact
4. Gmail → bexio: Email attachment creates expense entry

Authentication Deep Dive

bexio uses OAuth 2.0, the industry standard for API authorization. Understanding the dual authorization system is crucial.

Two Levels of Authorization

Level 1: Application Scopes When users connect your app, they grant specific permissions (scopes). Request only what you need—users see these permissions in the consent screen.

Available scope categories:

• contact_show, contact_edit — Contact management
• kb_invoice_show, kb_invoice_edit — Invoice access
• accounting_show — Read accounting data
• article_show, article_edit — Product management

Level 2: User Rights API requests execute with the permissions of the user who authorized the connection. If that user lacks permission to delete invoices in bexio, your API can't delete invoices either.

OAuth 2.0 Flow

1. Your app redirects user to:
   https://auth.bexio.com/realms/bexio/protocol/openid-connect/auth
   ?client_id=YOUR_CLIENT_ID
   &redirect_uri=YOUR_REDIRECT_URL
   &response_type=code
   &scope=contact_show kb_invoice_edit

2. User logs in and approves permissions

3. bexio redirects to your URL with authorization code

4. Exchange code for tokens at:
   https://auth.bexio.com/realms/bexio/protocol/openid-connect/token

5. Use access token for API requests

Token management:

• Access tokens are short-lived (typically 1 hour)
• Refresh tokens get new access tokens without user interaction
• Store refresh tokens securely and implement automatic token refresh

Workarounds for No Webhooks

• Polling: Check for changes periodically (every 5-15 minutes)
• Zapier: Uses polling but handles the infrastructure
• Third-party webhook services: Some integration platforms offer pseudo-webhook functionality

Handling Rate Limits

Based on community experience:

• Implement exponential backoff on 429 errors
• Cache responses where possible
• Batch requests when the API supports it
• Avoid unnecessary polling frequency

Limited Client Libraries

Official SDKs don't exist. Community libraries are incomplete. For production applications, expect to write custom code.

Magic Heidi Invoice API

The Magic Heidi Swiss Invoice QR Code API is an open, single-endpoint API for generating professional Swiss invoices with QR payment slips. No OAuth, no token refresh, no scopes—just an API key and a POST request.

How It Works

1. Send a POST request with your invoice data (sender, customer, line items)
2. Receive a PDF download URL valid for 24 hours
3. That's it—no OAuth flow, no developer portal registration

Python Example

import requests

response = requests.post(
    "https://europe-west6-magic-heidi.cloudfunctions.net/create_invoice_abstract_v1d",
    headers={"key": "your_api_key"},
    json={
        "user_details": {
            "name": "Muster GmbH",
            "address": "Bahnhofstrasse 1",
            "zip": "8001",
            "city": "Zurich",
            "iban": "CH93 0076 2011 6238 5295 7"
        },
        "customer_details": {
            "name": "Acme AG",
            "address": "Bundesplatz 3",
            "zip": "3011",
            "city": "Bern"
        },
        "invoice_items": [
            {
                "description": "Web Development",
                "quantity": 10,
                "unit_price": 150
            },
            {
                "description": "Design Review",
                "quantity": 3,
                "unit_price": 120
            }
        ],
        "language": "en",
        "currency": "CHF",
        "vat_enabled": true,
        "vat_percentage": 8.1,
        "vat_number": "CHE-123.456.789 MWST"
    }
)

data = response.json()
print(f"Download your invoice: {data['url']}")

JavaScript (Node.js) Example

const axios = require('axios');

const response = await axios.post(
  'https://europe-west6-magic-heidi.cloudfunctions.net/create_invoice_abstract_v1d',
  {
    user_details: {
      name: 'Muster GmbH',
      address: 'Bahnhofstrasse 1',
      zip: '8001',
      city: 'Zurich',
      iban: 'CH93 0076 2011 6238 5295 7'
    },
    customer_details: {
      name: 'Acme AG',
      address: 'Bundesplatz 3',
      zip: '3011',
      city: 'Bern'
    },
    invoice_items: [
      { description: 'Web Development', quantity: 10, unit_price: 150 },
      { description: 'Design Review', quantity: 3, unit_price: 120 }
    ],
    language: 'en',
    currency: 'CHF'
  },
  { headers: { key: 'your_api_key' } }
);

console.log(`Download your invoice: ${response.data.url}`);

Key Features

• Swiss QR invoices compliant with Swiss payment standards
• Multi-language: English, German, French, Italian
• CHF and EUR currency support
• VAT handling with configurable rates and VAT number
• Custom logos via URL
• QR-only mode for generating just the payment slip
• Free testing without an API key
• Open documentation on GitHub

Resources

• Magic Heidi Invoice API — GitHub
• Generate Swiss QR Invoices Programmatically — Blog Post
• bexio Developer Portal
• bexio API Documentation
• bexio Status Page
• bexio Marketplace — 120+ pre-built integrations