Financial InfrastructureFeatured

TxCore

TxCore is a robust financial transaction infrastructure designed to handle high-volume payment processing with guaranteed reliability. It implements double-entry accounting principles to ensure financial data integrity while providing a flexible webhook system for real-time notifications.

8 monthsSource

The Problem

Existing payment infrastructure solutions were either too expensive for startups or lacked the reliability and audit capabilities required for financial compliance. Building in-house solutions often resulted in data inconsistencies and reconciliation nightmares.

The Solution

Developed a distributed transaction processing system with built-in double-entry accounting, idempotent operations, and comprehensive webhook delivery guarantees. The system handles retries, dead letter queues, and automatic reconciliation.

Architecture

Distributed microservices architecture

Event-driven design with idempotent processors

Double-entry ledger with PostgreSQL

Redis for distributed locking and rate limiting

Webhook delivery system with exponential backoff

Technologies Used

PythonFastAPIPostgreSQLRedisRabbitMQDockerKubernetes

Challenges

1Ensuring exactly-once processing in a distributed system
2Building a ledger system that maintains ACID properties at scale
3Designing webhook delivery with guaranteed at-least-once semantics

Engineering Trade-offs

1Chose the saga pattern over two-phase commit for distributed transactions — avoids blocking locks across services, at the cost of eventual consistency and more complex compensating-transaction logic
2Chose event sourcing over storing only current state — gives a complete, replayable audit history, at the cost of higher storage volume and more complex read-model projections
3Required idempotency keys on every endpoint rather than only payment-critical ones — consistent guarantees everywhere, at the cost of extra validation overhead on low-risk endpoints

Lessons Learned

1Financial systems require a fundamentally different approach to error handling
2Idempotency is not optional in payment processing
3Observability is critical for debugging distributed financial transactions

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