Viacheslav – Java, Spring, Cassandra

Led the end-to-end architecture and development of a cloud-based medical diagnostics platform focused on Atrial Fibrillation (AFib) detection, translating raw ECG signals into clinically actionable insights.

Key Contributions: • Architected a high-performance ECG signal processing pipeline in Java, converting raw sensor data into visual ECG strips with annotated clinical markers for cardiologist review. • Designed and implemented a dynamic PDF reporting engine, tailored to meet strict clinical and regulatory requirements for cardiology use cases. • Owned and managed AWS infrastructure using CloudFormation templates, supporting production, staging, and development environments with robust CI/CD workflows. • Led a cross-functional engineering team of 3 developers, collaborating closely with medical professionals and domain experts to accurately implement complex healthcare logic. • Delivered a scalable and compliant solution, leveraging Java, ReactJS, PostgreSQL, and AWS services to support rapid data analysis and real-time decision-making in a clinical context. Impact: Enabled faster and more accurate AFib diagnostics by automating the transformation of sensor data into physician-ready insights, helping reduce diagnostic delays and improve patient care outcomes.

Designed and delivered a cloud-based medical diagnostics platform from the ground up, including core ECG signal parsing algorithms, automated PDF reporting, and clinical data annotation. Implemented multi-tenant infrastructure on AWS with per-client isolation to meet GDPR requirements. Built the MVP and production architecture, integrating backend services, data pipelines, and deployment workflows. Led all stages from R&D to real-world clinical deployment, ensuring both technical excellence and regulatory compliance.

Clutch.com is a U.S.-based marketing automation platform used by large retail brands to deliver personalized email, SMS, and push campaigns at scale. The platform enables real-time customer segmentation, behavioral targeting, and multi-channel orchestration. I contributed to backend development, working on high-load microservices that handled millions of interactions per day. Key features included event-driven campaign triggers, data enrichment pipelines, and real-time performance monitoring.

Contributed to the backend architecture of one of the leading U.S. marketing automation platforms — Clutch.com — supporting personalized, large-scale email and SMS campaigns for major retail brands. Key Contributions: • Enhanced and maintained a suite of microservices responsible for orchestrating time- sensitive marketing communications, ensuring seamless delivery during peak traffic periods such as Black Friday and Halloween. • Led the development of new features end-to-end, from design and implementation to production deployment, with a strong focus on performance, scalability, and fault tolerance. • Optimized service throughput and latency in a high-load environment by profiling Java applications and tuning asynchronous processing, database interactions, and message queues (Kafka/SQS). • Improved database interactions across both SQL (PostgreSQL) and NoSQL (Cassandra) layers, balancing consistency and performance in distributed systems. • Worked autonomously, delivering production-ready solutions with minimal supervision, while maintaining strong communication through regular sync-ups and collaborative reviews. Impact: Helped the platform scale to millions of personalized interactions per day, reducing latency under heavy load and contributing to increased engagement and conversion rates for enterprise clients. Sr. Engineer / TL

A startup that provides last-mile freight delivery service. It provides mobile applications for clients (clients can order delivery in an Uber-style manner), a Driver mobile App, and an Admin Application (to control and manage drivers and waybills).

Viacheslav was hired to create an Admin app backend based on the AWS serverless layer. Later, another Java developer was hired, so he started acting as an engineer, as an architect, and as a mentor for other developers.

• During 1 year, the team fully implemented all needed functionality, including optimizations for DB, basic functionality, reporting, and all kinds of searching the data in Admin App.
• Viacheslav created the whole AWS Lambda-oriented infrastructure, including caching, routing approach (single lambda per domain object, all actions for it), optimization, etc.

Sport league

• Participated in the development of the first app's 2nd version of microservice infrastructure. The app's infrastructure was developed as separate applications (like a web app (PHP), CMS (WordPress, PHP), and Java applications) that interacted with each other through different channels chaotically. So, he was signed up to implement single-style infrastructure using Spring Boot, Apache Kafka, and a microservice approach.
• Implemented new functionality, for instance, the auth service, that authorizes clients from different sources: web, mobile app, smart TV app, etc.
• Implemented data flows through Kafka and a few bridge services (to exchange data with legacy services through Mule and direct HTTP calls) and used some caching (Redis).
• Implement a new version of the second Mobile app (backend). Was the only backend developer with part-time support from the previous engineer. The main backend functionality covered the app's XML feeds and its statistic feeds. The backend read feeds, converted them to protobuf, and stored them in S3 as a file. Then the application read those feeds to show them to the user in the app. The team used a Serverless approach for that (AWS Lambdas + s3).

Antivirus, anti-spam gateway. Technically, the project consisted of 3 subsystems: web interface for end users, the antispam gateway kernel, and analyzing tool that provides anti-spam DB (Cassandra for Bayes model, based on previous emails, and analytics DB Elasticsearch)

The project consisted of legacy code with a few urgent tasks related to a memory leak, troubles with DB (elastic search), and race conditions.

• Viacheslav made code refactoring in a few steps, with intermediate discussions with the team, and after a few months, they got a more stable and robust application. It was critical: the application handled more than 10,000 emails per minute.
• Changed the architecture to make it work in a cluster.
• Implemented a more effective approach to analyzing e-mails (cooperative work with data-science engineers).
• Simplified the application to make it work as a microservice architecture infrastructure.
• Integrated Apache James (instead of postfix usage through JNI).

Java-based OSGi framework that compiles navigation data from Navteq to the internal format

Viacheslav participated in the Navigation data compiler for the vehicle automotive company's head unit. The compiler is built as an OSGi application. Wrapped by Jenkins (Hudson), and released as a complete tool with managing, planning, and automation for navigation data compiler. He worked with OSGi, Navigation data (geometry), math, Jenkins API (Hudson), SQL DBs, etc.