Olga — Backend Development freelancer in Cherkassy

Senior Java Backend Engineer with 10+ years of experience designing and delivering distributed microservices and integration platforms. Strong background in asynchronous processing, messaging systems, API gateways \u002F proxy services, and data pipelines. Extensive experience working with third-party API integrations. Proven track record in building reliable, scalable services with advanced retry, rate-limiting, queueing and validation mechanisms, and in supporting complex upgrade and migration workflows. Skills and Technologies Languages Java (11 \u002F 17 \u002F 21) TypeScript, Python, Kotlin Frameworks & Platforms Spring Boot (3.x), Spring MVC, Spring Security, Spring Data Microservice architecture Messaging & Asynchronous Processing Redis RabbitMQ AWS Kinesis AWS IoT PostgreSQL-based internal queues Scheduled and background job processing Cloud AWS (EC2, S3, Lambda, EventBridge, Batch) Docker (multi-stage builds) Jenkins, Bitbucket Pipelines, CircleCI Databases & Storage PostgreSQL MySQL MS SQL Server Cassandra APIs & Integrations REST, SOAP OAuth 2.0 (Salesforce Connected Apps, external APIs) Salesforce APIs (SOAP \u002F WSC) Third-party APIs (Sendbird, Google Maps, Mapbox, OSRM, Naurt, DoorDash, Uber Direct, Google Drive, Azure Files, AWS S3) SFTP Testing & Quality JUnit, Mockito, Testcontainers SonarQube Build & Tooling Maven, Gradle Git IntelliJ IDEA, Cursor Jira Flyway SpringDoc OpenAPI Observability & Reliability Micrometer, Prometheus Spring Boot Actuator Structured logging and metrics Retry, rate-limiting and fault-tolerance patterns Web Automation \u002F Scraping Selenium jsoup