Tomislav Herman
architect and engineer, from design to production.

Distributed transaction atomicity

Designed a two-phase commit protocol ensuring transactions across independent participants either fully complete or cleanly abort.

Async transaction processing

Restructured tangled async logic into explicit saga steps, each with defined execute and reverse logic, coordinated via Kafka.

Authorization across microservices

Built a JWT-based system that shipped resolved access rules to each service, eliminating runtime calls to a central auth service.

Distributed tracing across Kafka

Propagated Datadog trace context through Kafka message headers so a single transaction was visible as one trace across all services.

Legacy integration compatibility

Bridged synchronous bank API expectations with an internally async transaction architecture, keeping existing integrations intact without reverting the internal redesign.

Custom data validation at platform level

Introduced JSON Schema-based record validation into a developer platform, enabling clients to enforce their own data contracts without custom code.

Billing system redesign

Moved pricing logic from SQL stored procedures to Recurly, modelling features as add-ons and eliminating fragile in-house calculation code.

Image delivery at scale

Replaced eager pre-generation of image variants with on-demand resizing and S3 caching, reducing storage and removing backend bottlenecks.

Documentation architecture

Introduced the Diátaxis model to separate tutorials, guides, explanations, and references; automated OpenAPI generation to keep API docs in sync with code.