Віталій

VITALII MARTYNIUK
Software Engineer
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Kyiv, Ukraine

Summary
Senior Software Engineer (Backend/Data) with 6+ years of experience in .NET and cloud platforms (AWS & Azure). Delivered and contributed to
applications and systems across multiple domains. Built serverless backends on AWS Lambda for OLAP analytics. Designed lakehouse data pipelines
using AWS Glue/PySpark/S3, orchestrated with AWS Step Functions. Maintained and evolved microservices-based systems.

Experience

Trinetix
Data Engineer (Python/AWS/OpenSearch) 02/2023 - Present
Develop and operated an AWS lakehouse: S3, Athena, Glue + PySpark for incremental ingest/cleansing/conformance, curated marts serving the
platform’s OLAP analytics and orchestrated workflows with AWS Step Functions.
• Reporting engine - Built a dynamic SQL reporting framework powered by JSON-defined templates, supporting Redshift push-down aggregations, fine-
grained role-based filters, pagination, caching, and data exports for multiple client interfaces. Regularly dealt with performance challenges due to a
strict 30-second query limit, which required constant tuning and optimization. Through iterative improvements, managed to reduce total query cost by
about 40% and significantly improve overall performance.
• Entity-level delta tracking - Designed and implemented a unified delta tracking mechanism for multiple data sources, allowing incremental updates of
complex analytical models and significantly reducing recomputation time in a big data environment.

Trinetix
Backend Engineer (.NET/Azure/AWS/GraphQL/Microservices/Serverless) 05/2021 - 02/2023
Built the backend for an enterprise workplace/room-booking solution: desk and meeting-room search and reservations, access rules, and scheduling.
Also worked on a second project - an OLAP analytics platform for large-scale data analysis.
• Workplace/Booking - Built backend for a microservices workplace platform: desk/room booking, availability search, reservation lifecycle, access rules.
Developed REST APIs and the transition to GraphQL to reduce over-fetching and streamline client integration. Maintained and develop event-driven
flows via Azure Service Bus.
• OLAP platform - Developed a fully serverless backend on AWS Lambda (.NET) with GraphQL API. OLAP-centric system: curated data marts from data
side feed the read-only analytics; OLTP is limited to operational metadata (user settings/filters, export jobs, audit). Personally built a spreadsheet
generating module - from investigation open-source libraries to implementing a low-level engine for object mapping and spreadsheet generation.
Delivered an AWS Lambda function to export the generate file.

Hideez Group Inc.
Software Engineer (.NET/Blazor/WPF) 12/2019 - 05/2021
Contributed to the development of the admin portal and Identity Provider (IdP). Designed and implemented from scratch an internal licensing server.
• Authentication Server (admin portal & IdP) - Develop and maintained a Blazor + ASP.NET Core admin portal for device & access lifecycle: users,
devices, MFA policies, directories/roles. Implementation passwordless SSO/MFA flows, FIDO2/WebAuthn, passkeys; Integration via SAML 2.0 /
OpenID Connect (Entra ID/AD FS).
• Internal Licensing Server - Designed and implemented from scratch a licensing service for hardware keys: domain model, DB schema, REST APIs,
admin operations (issue/renew/revoke). Built cryptographic licensing: signed license issuance/verification (RSA/ECDSA), key rotation, anti-
tamper/replay protections. Implemented business rules: per-device / per-user models, subscriptions/trials, quotas & feature flags

IT-Enterprise
Backend Developer (ASP.NET MVC) 10/2019 - 12/2019
Contributed to the CRM module of the company’s ERP platform: leads, accounts/contacts, opportunities (deals), product catalog, and basic reports -
using C# and the company’s internal code library.

Education

State University of Trade and Economics 01/2019 - 12/2022
Bachelor's degree, Economics, Management and Psychology

IT STEP Computer Academy 01/2017 - 12/2020
Software design and development

Languages
English B1 Ukrainian Native Russian Native