Privacy Policy
Last updated: February 8, 2026
1. Introduction
This Privacy Policy explains how Nikola Jevtić ("we", "us", "our"), operating as BillZen, collects, uses, and protects your personal data when you use our invoicing service at billzen.app.
We are committed to protecting your privacy and complying with the General Data Protection Regulation (GDPR) and Spanish data protection laws (LOPDGDD).
Data Controller: - Name: Nikola Jevtić (Autónomo) - Address: Carrer de Don Armando Palacio Valdés 10 4, 46010 Valencia, España - Email: contact@billzen.app
2. Data We Collect
2.1 Account Information
- Email address
- Password (encrypted, we cannot see it)
- Name (optional)
2.2 Profile Information
- Business name
- Business address
- Tax identification number (NIF/VAT)
- Phone number (optional)
2.3 Financial Information
- Bank account details (encrypted)
- Payment information (processed by Stripe, we don't store card details)
- Subscription history
2.4 Invoice Data
- Client names and addresses
- Invoice amounts and items
- Payment status
2.5 Technical Data
- IP address
- Browser type
- Device information
- Usage logs
3. How We Use Your Data
| Purpose | Legal Basis (GDPR) |
|---|---|
| Provide the invoicing service | Contract performance |
| Process payments | Contract performance |
| Send transactional emails | Contract performance |
| Customer support | Legitimate interest |
| Improve our service | Legitimate interest |
| Prevent fraud | Legitimate interest |
| Legal compliance | Legal obligation |
We do NOT use your data for: - Selling to third parties - Targeted advertising - Profiling for marketing
4. Data Sharing
We share your data only with:
| Third Party | Purpose | Location | Safeguards |
|---|---|---|---|
| Stripe | Payment processing | USA | EU-US Data Privacy Framework |
| Resend | Email delivery | USA | EU-US Data Privacy Framework |
| Hetzner | Server hosting | Germany | GDPR compliant |
We may also disclose data if required by law or court order.
5. Data Storage and Security
5.1 Location
Your data is stored on servers in Germany (Hetzner), within the European Union.
5.2 Security Measures
- Encryption in transit (HTTPS/TLS)
- Encryption at rest for sensitive data
- Password hashing (bcrypt)
- Bank account encryption
- Regular security updates
- Access controls
5.3 Retention Period
| Data Type | Retention |
|---|---|
| Account data | Until account deletion + 30 days |
| Invoice data | 5 years after creation (legal requirement) |
| Payment history | 7 years (tax compliance) |
| Server logs | 90 days |
6. Your Rights (GDPR)
You have the right to:
| Right | Description |
|---|---|
| Access | Request a copy of your data |
| Rectification | Correct inaccurate data |
| Erasure | Delete your account and data ("right to be forgotten") |
| Portability | Export your data in a machine-readable format |
| Restriction | Limit how we process your data |
| Objection | Object to certain processing |
| Withdraw consent | Where processing is based on consent |
To exercise these rights, contact us at: contact@billzen.app
We will respond within 30 days.
7. Cookies
We use only essential cookies required for the service to function:
| Cookie | Purpose | Duration |
|---|---|---|
| sessionid | User session | Until logout |
| csrftoken | Security | 1 year |
We do NOT use: - Tracking cookies - Advertising cookies - Third-party analytics
8. Children's Privacy
BillZen is not intended for use by individuals under 18 years of age. We do not knowingly collect data from children.
9. Changes to This Policy
We may update this Privacy Policy from time to time. We will notify you of significant changes via email or in-app notification.
10. Contact & Complaints
Questions or requests: Email: contact@billzen.app
Complaints: If you believe we have violated your privacy rights, you may file a complaint with the Spanish Data Protection Agency (AEPD): - Website: www.aepd.es - Address: C/ Jorge Juan, 6, 28001 Madrid, España
11. Spanish Law Compliance
This Privacy Policy complies with: - General Data Protection Regulation (GDPR) - EU 2016/679 - Ley Orgánica de Protección de Datos y Garantía de Derechos Digitales (LOPDGDD) - Spain
This document was last reviewed on February 8, 2026.