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Alexandru – Python, React, AWS, experts in Lemon.io

Alexandru

From Romania (UTC+3)flag

Full-stack Web Developer|Senior

Alexandru – Python, React, AWS

Alexandru is a senior full-stack/cloud engineer with deep expertise in Python, FastAPI, AWS, Kubernetes, and Terraform, complemented by strong distributed-systems and DevOps skills. He has led architecture and implementation for AI, ML, and real-time data platforms, and brings startup co-founder and tech lead experience. His communication is clear and structured, with a strong product-first mindset and proven ability to own complex infrastructure. Frontend skills are Next.js-focused and lighter than his backend strengths.

7 years of commercial experience in
AI
Architecture
Healthcare
Healthtech
Machine learning
SaaS
Web development
Software development
Main technologies
Python
6 years
React
4 years
AWS
6 years
Next.js
4 years
FastAPI
6 years
Typescript
1 year
Additional skills
AI
Java
Spring
AI chatbot development
Docker
Tensorflow
Kubernetes
Terraform
OpenAI API
Claude API
Kafka
Flask
MongoDB
DevOps
Snowflake
Amazon S3
Direct hire
Possible
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Experience Highlights

Senior Full-stack Engineer
Sep 2025 - Ongoing8 months
Project Overview

Enterprise-grade, low-code conversational AI platform that allows businesses to build and deploy intelligent chatbots and voice assistants that connect seamlessly with backend systems (like ERP, CRM, and SaaS applications) to automate routine tasks.

Responsibilities:
  • Migrated training and inference Python code-base to newer library versions (TensorFlow, Keras, PyTorch, Transformers);
  • Implemented a continuous delivery pipeline that reduced the deployment time by 40%;
  • Troubleshot complex workflows involving multiple ML models through Python and Java code bases in a Kubernetes deployment;
  • Designed and implemented sandboxes for ML models, local training, and inference using Docker, Python, and Bash scripting, increasing the error detection delay from 3h to 15min;
  • Secured artifacts access by integrating secret manager services in existing CI pipelines and automated secret rotation using JFrog API.
Project Tech stack:
Python
Terraform
Kubernetes
Docker
Tensorflow
AI chatbot development
Senior Full-stack Engineer
Jul 2025 - Feb 20267 months
Project Overview

Specialized AI tool for automated personal branding that leverages LLMs to generate high-engagement LinkedIn posts in a user’s unique voice.

Project gallery:
Portfolio example for Brewbrand.ai by Alexandru, SENIOR FULL-STACK ENGINEER
Portfolio example for Brewbrand.ai by Alexandru, SENIOR FULL-STACK ENGINEER
Portfolio example for Brewbrand.ai by Alexandru, SENIOR FULL-STACK ENGINEER
Responsibilities:
  • Implemented the business flows by leveraging the Workflow-as-a-Service cloud model, using TypeScript, Node.js, and Upstash;
  • Created UI components using React, Next.js, and Tailwind with reactive updates using Convex;
  • Secured the application with SSO login using Clerk;
  • Streamlined the CI/CD process using GitLab CI and Vercel API;
  • Built agent workflows by integrating the OpenAI and Claude APIs;
  • Implemented multi-tier subscriptions using the Paddle API.
Project Tech stack:
Typescript
Next.js
Tailwind CSS
GitLab CI
CD
React
Claude API
OpenAI API
Tech Lead
Dec 2024 - Sep 20258 months
Project Overview

Enterprise ETL system for processing millions of Electronic Health Records (EHR) produced by multiple healthcare organizations

Responsibilities:
  • Implemented transformations in Java 8 using Apache Crunch and MapReduce;
  • Introduced common utilities leveraging Java 8 functional programming features to reduce the transformation implementation code by up to 60%;
  • Created Python scripts for migrating from Snowflake to Oracle Autonomous Data Warehouse, using AWS S3 and Paquet;
  • Coordinated technical discussions and initiatives in a team of five engineers.
Project Tech stack:
Java
Python
Snowflake
Vertica DB
Amazon S3
Senior Back-end Engineer
Nov 2023 - Jul 20251 year 8 months
Project Overview

A scalable, highly available API for extracting valuable insights from live data feeds (e.g., radio broadcasts, TV shows) by performing transcription, speaker detection, sentiment analysis, and summarization.

Responsibilities:
  • Developed an event-driven micro-services system using Python and Java around the Orchestrator pattern;
  • Created a Python framework isolating the reusable code of a stream processor, allowing the team to focus on the business logic'
  • Configured a Pulsar cluster for handling large volume data flows between application;
  • Implemented a centralized AVRO schema repository for domain model standardization and applied AVRO SerDe for efficient data transfers, achieving 4x less bandwidth consumption compared to JSON;
  • Secured the system using the OIDC authorization protocol with a self-hosted Keycloak deployment;
  • Dockerized all components and deployed as a Kubernetes cluster, leveraging the AWS EKS;
  • Optimized resource utilization by implementing custom auto-scaling rules, using Keda and Karpenter;
  • Implemented monitoring systems for collecting application metrics and logs using Prometheus Node Exporter, Promtail, Loki, and Grafana.
Project Tech stack:
Java
Python
FastAPI
Kafka
Spring
Spring WebFlux
OAuth
Kubernetes
Terraform
DevOps Engineer
Apr 2025 - Jul 20253 months
Project Overview

A cloud infrastructure modernization project focused on transforming manually managed environments into a scalable Infrastructure-as-Code (IaC) platform. The solution was designed to support customizable deployments across multiple tenants and regions, enabling consistent provisioning, simplified operations, improved maintainability, and faster delivery of infrastructure changes.

Responsibilities:
  • Isolated system components into reusable Terraform modules and imported existing infrastructure;
  • Templated infrastructure manifests using Terragrunt, splitting the Terraform centralized state into isolated states;
  • Organized system components into Helm charts and grouped tightly-coupled components under Helmfiles;
  • Integrated SOPS for encrypting secrets in version control and using them inside Terraform and Helm modules.
Project Tech stack:
Terraform
Terragrunt
Helm
Senior Back-end Engineer
Sep 2023 - Nov 20232 months
Project Overview

Web application for transcoding media content in real-time that enables the integration between a transcription system and live data feeds (e.g. microphone feed in browser, IPTV camera stream)

Responsibilities:
  • Used Python multiprocessing primitives for handling parallel transcoding processes;
  • Implemented inter-process communication using Unix socket file descriptors;
  • Handled multiple connections using the Selector API for I/O multiplexing;
  • Integrated Pulsar consumer and producer API for I/O transfer.
Project Tech stack:
Python
FFmpeg
Full-stack Engineer
Dec 2020 - Sep 20232 years 8 months
Project Overview

Implemented the end-to-end process for delivering the best-in-market STT model for the Romanian language, from data collection to model deployment.

Responsibilities:
  • Developed the data annotation platform using Java, React, MongoDB, and GCS;
  • Trained and evaluated a wav2vec model using Python, PyTorch, and Fairseq, managing to achieve a WER (Word Error Rate) down to 5%;
  • Implemented a consumer-producer event-driven system for serving the model, using Python and RabbitMQ;
  • Exposed an HTTP API using Flask.
Project Tech stack:
Python
Flask
PyTorch
Java
React
Back-end (Java) Engineer
Dec 2020 - Aug 20217 months
Project Overview

An event-driven system that integrates with railway hardware and centralizes diagnostic data on a single platform, enabling efficient monitoring and alerting.

Responsibilities:
  • Developed and deployed Spring, Java 11 micro-services to a self-managed Kubernetes cluster;
  • Created and tested RESTful endpoints using Spring and RabbitMQ;
  • Implemented persistence layer using JPA, Hibernate, PostgreSQL, and Liquibase;
  • Performed testing with JUnit, Mockito, and Spring Mock MVC;
  • Implemented a custom Keycloak plugin.
Project Tech stack:
Java
Spring
RabbitMQ
Kubernetes
PostgreSQL
Back-end (Java) Engineer
Jun 2019 - Dec 20201 year 6 months
Project Overview

A healthcare imaging platform designed to securely retrieve, view, store, and share medical imaging data across multiple locations. The solution included a cloud-based PACS architecture and a zero-footprint DICOM viewer, enabling healthcare professionals to access and collaborate on diagnostic images without requiring local software installation, while maintaining security, scalability, and regulatory compliance.

Responsibilities:
  • Developed and tested RESTful web services with Spring, Java 8, and implemented Reporting Database pattern using Apache Solr;
  • Implemented persistence layer using JPA, Hibernate, PostgreSQL, and Liquibase;
  • Load tested the web platform by simulating various user flows using JMeter, BlazeMeter, and Selenium.
Project Tech stack:
Java
Spring
PostgreSQL
JPA
Hibernate
Liquibase
Apache JMeter
Selenium
Senior Full-stack Engineer
Dec 2019 - Dec 20201 year
Project Overview

Web platform for processing multi-media files, including transcription, translation, and AI-enabled insights.

Project gallery:
Portfolio example for Transcription Web Platform by Alexandru, SENIOR FULL-STACK ENGINEER
Portfolio example for Transcription Web Platform by Alexandru, SENIOR FULL-STACK ENGINEER
Portfolio example for Transcription Web Platform by Alexandru, SENIOR FULL-STACK ENGINEER
Portfolio example for Transcription Web Platform by Alexandru, SENIOR FULL-STACK ENGINEER
Responsibilities:
  • Created backend and frontend applications using React and Java Spring;
  • Leveraged AWS EKS and Docker for deployment, and Cloudflare R2 for file storage;
  • Integrated Stripe API for both subscriptions and one-time payments;
  • Implemented upload flow in AWS Step Functions for handling large uploads.
Project Tech stack:
Java
Spring Boot
Stripe API
PostgreSQL
React
JavaScript
Docker
Kubernetes
AWS Lambda
AWS
Cloudflare

Education

2021
Computer Science
Bachelor

Languages

English
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