Open to opportunities

Valentin User

@valentinuser2

Message

I build reliable Java and Kotlin backend platforms for mission-critical communications.

Germany

Message

What I'm looking for

I'm looking for a backend role where I can build reliable distributed systems, solve concurrency and correctness problems, and contribute through testing, design rationale, code review, and platform-wide engineering improvements.

At TASSTA, I build and operate a 3GPP mission-critical communications platform where message correctness and delivery are safety-critical. I rebuilt the Diameter send path, cutting p50 latency by roughly 6x under sustained concurrent load, and designed distributed group-call architecture that reduced peak per-server load by more than an order of magnitude.

I own a multi-tenant HTTP/WebSocket gateway, high-availability work across multi-pod deployments, and service-fleet migrations including Spring Boot 2 to 3, Hibernate 6, Spring Cloud, Java-to-Kotlin, and JUnit 4 to 5. I review and merge a large share of team contributions, with 952 merges from 13 other engineers alongside written design rationale.

Earlier at TT Development, I built Diameter, SIP call-control, messaging, OAuth2/OIDC, and subscriber-profile services. I also created the standards-conformance and interoperability harness still used for every release, covering 26 ETSI plugtest suites and 25 vendor interoperability profiles.

Experience

Work history, roles, and key accomplishments

Current

Senior Software Engineer

Current

TASSTA

Jul 2022 - Present (4 years 1 month)

Rebuilt the Diameter send path to cut p50 latency by roughly 6x under concurrent load and designed a two-tier distributed architecture for regrouped group calls. Led high-availability fixes, Spring Boot 2 to 3 migration, and Java to Kotlin migration across the fleet.

Education

Degrees, certifications, and relevant coursework

Peter the Great St. Petersburg Polytechnic University

Bachelor of Science, Computer Science and Engineering

2015 - 2018

Pursued a Bachelor of Science in Computer Science and Engineering, recognized in the German ANABIN database as equivalent to a German Bachelor's degree.