Benyamin Delshad

Backend Software Engineer

Benyamin Delshad

I build event-driven backend systems in Kotlin and Java: microservices, Kafka pipelines, and REST APIs that hold up in production.

Frankfurt am Main, Germany

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About

I'm a backend engineer with 4+ years of experience building microservices and REST APIs. I work at Yatta Solutions in Frankfurt, a German software company that mixes client consulting with building its own products. I'm on Checkout, Yatta's e-commerce platform for digital goods, covering payment, fulfillment, and delivery. My current toolkit: Kotlin, Spring Boot, Apache Kafka, Temporal, and Domain-Driven Design, applied to event-driven systems that move real products to real customers.

Before this I delivered client projects for the energy and logistics industries, and before industry I did research on distributed systems and algorithms in Switzerland, Austria, and France.

I care about how teams work, not just what they ship: I've facilitated retrospectives, organized team events, and taught at every stage of my career, from CS tutorials at the University of Tehran to software-engineering courses at St. Gallen.

I work in English (C1), get along in German (B1, currently taking a course), and Persian is my native language.

Away from the keyboard I hunt authentic local food while traveling, study Middle-earth linguistics, keep up my Wizarding World lore (Hufflepuff, sorted and content), and build detailed LEGO models, including Hogwarts Castle.

Tech Stack

Languages

  • Kotlin
  • Java
  • Python
  • SQL
  • Bash
  • C/C++

Backend

  • Spring Boot
  • REST APIs
  • Microservices
  • Event-driven architecture
  • Apache Kafka
  • Avro + Schema Registry
  • Temporal workflow orchestration
  • Idempotency
  • Dead-letter queues

Data

  • PostgreSQL
  • Oracle DB
  • Flyway
  • JPA/Hibernate

Infrastructure

  • Kubernetes
  • Helm
  • ArgoCD
  • Docker/Podman
  • GitHub Actions
  • GitLab CI/CD
  • AWS S3
  • Confluent Cloud
  • Micrometer + structured logging
  • k6 load testing
  • JVM memory tuning

Practices

  • Domain-Driven Design
  • Hexagonal architecture
  • Clean Code
  • TDD (JUnit, Kotest, MockK, Testcontainers)
  • Temporal replay tests
  • SonarCloud quality gates
  • Scrum
  • Code review

Experience

Software Engineer · Checkout · Yatta Solutions

Jul 2026 – present · Frankfurt am Main, Germany
  • Architected and built a greenfield, event-driven fulfillment service (Kotlin, Spring Boot, Temporal) that turns a completed purchase into tickets, wallet links, a delivery email and a print-at-home PDF. Live since September 2026 for a regional public-transport association: about 10,000 production workflows in its first ten days with zero failed.
  • Load-tested with k6 against real webhooks before go-live and found a concurrency race in the Temporal workflow that dropped early Kafka replies. Fixed it replay-safely with workflow versioning and replay tests: clean runs from 79% to 100% under load, worst case from ~5 minutes to 34 s. The first overnight batch then ran 2,532 subscription renewals with zero failures (p95 2.1 s).
  • Diagnosed a JVM Metaspace out-of-memory crash under load on Kubernetes and fixed the buildpack's memory sizing, taking restarts under load to zero and unblocking the production rollout.
  • Ran the production releases (GitOps with Helm and ArgoCD), set the release order across dependent services, and kept go-live checklists with rollback plans. After a deployment-downtime incident, filed the analysis and proposed splitting the HTTP API from the workflow worker.
  • Built Kafka and Avro consumer pipelines with per-listener retry classification, a dead-letter path and stalled-consumer metrics, and evolved event contracts across services without breaking consumers or in-flight workflows.
  • Implemented VDV-KA compliant Aztec barcode rendering (ZXing plus a hand-written 1-bit PNG encoder), verified by decode-back tests; the barcodes are scanned by real ticket-inspection devices.
  • Structured the service as independently extractable bounded contexts (DDD, hexagonal), with streaming document paths and sanitized error boundaries that keep signed URLs and personal data out of logs. Reviewed colleagues' pull requests; reviews surfaced lost-update races and duplicate-email risks and changed final designs.
  • Kotlin
  • Spring Boot
  • Temporal
  • Apache Kafka
  • Avro
  • PostgreSQL
  • Flyway
  • AWS S3
  • Kubernetes
  • Helm
  • ArgoCD
  • k6
  • Gradle

Software Engineer · SMA Solar project · Yatta Solutions

Dec 2023 – Jun 2026 · Frankfurt am Main, Germany
  • Developed an EEBUS protocol driver to process grid-based power-limitation requests, ensuring compliance with German energy regulations (§ 14a EnWG and § 9 EEG).
  • Architected GitLab CI/CD pipelines automating builds, code formatting, static analysis, and test coverage.
  • Built core energy-management services and APIs in a cross-functional team, optimizing end-user energy consumption and costs.
  • Helped achieve an 80%+ customer-satisfaction score (NPS) by consistently delivering high-quality software.
  • Java
  • REST APIs
  • Python
  • Bash
  • TypeScript
  • GitLab CI

Software Engineer · Rhenus Logistics project · Yatta Solutions

Apr 2022 – Nov 2023 · Frankfurt am Main, Germany
  • Cut shipment-processing overhead with an automated compliance system that proactively blocks high-risk shipments to sensitive destinations.
  • Engineered a Spring Boot REST service providing end users with real-time shipment quotes.
  • Java
  • Spring Boot
  • JavaScript
  • Oracle DB

Doctoral Researcher & Teaching Assistant · University of St. Gallen

Oct 2020 – Mar 2022 · St. Gallen, Switzerland
  • Accelerated distributed-systems development by designing a domain-specific language that automates operation-level consistency inference.
  • Taught in courses on engineering software systems, software engineering, and programming for data science.
  • Java
  • NoSQL
  • Maven
  • JML

Research Intern (M.Sc. thesis), Game Theory & Simulation · Institute of Science and Technology Austria (ISTA)

Feb 2020 – Sep 2020 · Klosterneuburg, Austria
  • Validated theoretical research by building evolutionary game-theory simulations to analyze probabilistic cooperation strategies, under the supervision of Prof. Krishnendu Chatterjee.
  • MATLAB
  • Algorithms

Research Intern, Graph Algorithms for Transit Routing · IRIF

Apr 2019 – Sep 2019 · Paris, France
  • Modeled public transit networks as temporal graphs and designed algorithms to assess infrastructure changes using real-world datasets.
  • C/C++
  • Algorithms
  • Graph theory

Teaching Assistant · University of Tehran

Sep 2015 – Feb 2018 · Tehran, Iran
  • Ran tutorials across core CS courses: graph theory and applications, design and analysis of algorithms, fundamentals of combinatorics, advanced programming (C++), and foundations of programming (Java).
  • C++
  • Java
  • Algorithms

Education & Achievements

M.Sc. Computer Science · Université Paris Cité

2018 – 2020 · Paris, France
  • Completed the MPRI track (Master Parisien de Recherche en Informatique); master's thesis supervised by Prof. Krishnendu Chatterjee (ISTA).
  • Merit-based scholarship from the Mathematical Sciences Foundation of Paris (Fondation Sciences Mathématiques de Paris).

B.Sc. Computer Science · University of Tehran

2014 – 2018 · Tehran, Iran
  • Ranked 4th nationally in the Iranian graduate-entrance exam (Concours) for Computer Science (2017), after ranking 8th in 2016.
  • Two-time bronze medalist, Iranian National Mathematics Competition for University Students (2016, 2017).
  • Three-time ACM/ICPC contestant, Asia Region, Tehran site (2014–2016); ranked 8th in 2016.
  • Prof. Ahrabian Memorial Faculty Fellowship: awarded to the top 7 students across Computer Science, Mathematics, and Statistics.
  • University of Tehran Foundation Fellowship: top 500 among 30,000+ students.