Back to Consultancy
Payment Systems
Stripe integration, financial transactions, and VAT compliance
Stripe Integration
Secure payment processing with webhook handling and idempotency
- Webhook handling that validates every request is genuine
- Complete payment lifecycle from intent to confirmation
- Idempotent processing so duplicate requests are safe
- Edge case handling for unusual payload formats
- Secure API key storage that rotates without downtime
- Automatic retries when Stripe has temporary issues
- Isolated payment calls that keep secrets separate from app code
Transaction Design
ACID-compliant financial logic with double-entry bookkeeping
- Balance holds that reserve funds until a transaction completes
- Double-entry bookkeeping for accurate records and easy audits
- Atomic operations where partial failures roll back completely
- Full audit trail so you can trace any transaction
- Protection against duplicate charges from retries
- Per-user isolation so one customer never affects another
- Constraints that prevent negative balances before they happen
- Automatic enforcement of valid state transitions
VAT & Compliance
EU VAT evidence collection and regulatory compliance
- Automatic VAT evidence capture for EU sales
- Location verification from multiple sources
- Billing address validation at checkout
- Payment method origin tracking
- All evidence stored with each transaction
- Timestamped records ready for audits
Choosing the Right Database for Payments
Financial systems need guarantees that NoSQL databases weren't designed for. We use relational databases where they matter most.
NoSQL Trade-offs
- Great for flexible schemas and scale
- Limited cross-table transaction support
- Eventual consistency in some cases
- Best for content, sessions, caching
Why PostgreSQL for Money
- Transactions that either fully succeed or fully roll back
- Constraints that prevent invalid states
- Business logic close to the data
- Proven reliability for financial workloads