Under the Hood
How Works
A deep dive into the architecture that makes private, secure, and open by design.
Architecture
Decentralized by Design
Receipt data stays with the merchant who issued it. There is no central database of all purchases. Consumers receive a token — not the data — which they use to fetch their receipt on demand.
No honeypot to hack. No single entity sees all your purchases. GDPR compliant by architecture, not by policy. Scales infinitely with no central bottleneck.
Merchant-Hosted Data
Each merchant stores their own receipt data and serves it via a simple REST API. Consumers fetch receipts with a token received at checkout.
Token-Based Access
A QR code at checkout contains a secure token — no account needed, no personal data shared. Your app uses this token to retrieve the receipt.
Anti-Scraping
Receipt IDs are random UUIDs, access requires a valid token, and rate limiting prevents bulk data harvesting.
Privacy
Zero Customer Data
The core receipt contains zero customer personally identifiable information. No name, no email, no phone number, no loyalty ID. Privacy is not an opt-in feature — it's the default.
How compares to existing solutions:
Standard
- ✓No email required
- ✓No account needed
- ✓No purchase tracking
- ✓Consumer controls their data
Typical Digital Receipt
- ✗Email required to receive receipt
- ✗Must create an account
- ✗Full purchase history tracked
- ✗Company controls your data
Security
Forgery-Proof Receipts
Every receipt is cryptographically signed by the merchant using the same proven infrastructure as HTTPS. A receipt from TechStore AG can only be signed by TechStore AG — just as only techstore.ch can present a valid TLS certificate for its domain.
How It Works
Merchants sign receipts with their private key (ES256/RS256). Anyone can verify authenticity using the merchant's public key hosted at their domain. No forgery possible without the private key.
Third-Party Verification
Warranty providers, banks, or tax authorities can independently verify any receipt — without contacting the original merchant.
Fiscal Compliance
Built-in support for fiscal device signatures (Germany TSE, Austria RKSV, Switzerland GeBüV) alongside the merchant signature.
Ecosystem
GTIN: The Key to Everything
The GTIN (Global Trade Item Number) is the barcode on every product. When included in an receipt, it unlocks a world of connected services — from allergy warnings to carbon tracking.
What GTIN Enables
Nutrition & Allergens
Cross-reference purchases with Open Food Facts for allergen warnings, Nutri-Score, and ingredient lists.
Product Recalls
Automatic alerts when a purchased product is recalled via EU Safety Gate or national databases.
Warranty Registration
Link purchases to manufacturer warranty portals for automatic registration and expiry tracking.
Carbon Footprint
Product-level CO₂ data from carbon databases, enabling personal environmental impact tracking.
EU Digital Product Passport
GTIN serves as the shared key linking receipts to the upcoming EU Digital Product Passport ecosystem.
Health Apps
Connect grocery receipts to health and dietary tracking apps for personalized nutrition insights.
Modularity
Extensions for Every Need
The core is minimal by design — only essential fields are required. Everything else lives in namespaced extensions that can be added without breaking compatibility.
Warranty duration, type, expiration date, and registration URL per item.
Points earned, redeemed, and balance — with privacy-preserving hashed member IDs.
Nutri-Score, allergens, calories, organic/vegan status per product.
CO₂ footprint per item and total, sourced from carbon databases.
Link to EU DPP data per item via GTIN and DPP URI.
Recall status, severity, and consumer action instructions per product.
Any organization can define their own namespaced extensions without affecting the core spec.
Compliance
Built for Global Compliance
is designed to meet regulatory requirements across jurisdictions — from EU e-invoicing directives to Swiss bookkeeping regulations.
EU E-Invoice (EN 16931)
Field mapping to EN 16931 ensures receipts can be transformed into compliant e-invoices.
Germany (KassenSichV / TSE)
Fiscal signature support for German TSE devices with transaction numbers and signature counters.
Austria (RKSV)
RKSV-compliant with encrypted turnover counters and receipt chain hashing.
Switzerland (GeBüV)
Meets Swiss bookkeeping ordinance requirements for integrity, retention, and non-proprietary format.
GDPR
No customer PII in core receipts. Decentralized architecture means no central data controller.
Dive Deeper
Read the Full Specification
The complete technical specification is open and available on GitHub. Review it, comment on it, help improve it.