Nicolas is available for hire
Hire NicolasNicolas Charczewski
Verified Expert in Engineering
Software Developer
Rosario, Santa Fe Province, Argentina
Toptal member since December 19, 2016
Bio
Nicolas is a full-stack computer engineer with a strong background in secure, fast, and scalable Java and Node.js applications. He quickly learns and advises on new technologies. His experience as a technical leader has sharpened his communication skills, making him a strong asset for decision-making. With over 25 years of experience, Nicolas is highly adaptable and ready to face any challenge.
Portfolio
Extenteam
Node.js, PostgreSQL, Kubernetes, Docker, REST, Redis, Amazon, Spring Boot
NaviHealth
Jasmine, JPA 2, JProfiler, Apache JMeter, Cucumber, JUnit, REST, Spring...
Jeeves
JavaScript, Node.js, Express.io, MySQL, Jenkins, Docker, IntelliJ IDEA, Java
Experience
- Java - 15 years
- SQL - 10 years
- Spring - 10 years
- Oracle - 10 years
- Node.js - 8 years
- Kubernetes - 5 years
- Docker - 5 years
- JProfiler - 3 years
Availability
Part-time
Preferred Environment
Oracle, Git, IntelliJ IDEA, Java, Node.js, Docker
The most amazing...
...thing I've developed is a healthcare app that integrates biometric devices, giving me the chance to build something that truly improves people's lives.
Work Experience
Senior Software Engineer
2024 - PRESENT
Extenteam
- Delivered PMS integrations with Airbnb, Hospitable, and Calry using Node.js, enhancing data sync and automation for a hospitality platform.
- Designed and deployed scalable back-end systems using Docker, Kubernetes, and PostgreSQL, ensuring high availability and performance.
- Implemented caching, queuing, and monitoring solutions with Redis and Grafana, improving system reliability and observability in AWS.
Technologies: Node.js, PostgreSQL, Kubernetes, Docker, REST, Redis, Amazon, Spring Boot
Senior Technical Leader
2014 - 2025
NaviHealth
- Led technical projects for multiple projects in WellSky.
- Developed software in multiple languages within an Agile environment.
- Contributed to defining the production continuous release process.
Technologies: Jasmine, JPA 2, JProfiler, Apache JMeter, Cucumber, JUnit, REST, Spring, MongoDB, Oracle, Angular, AngularJS, Java, Spring Boot, Apache Kafka
Senior Engineer
2022 - 2024
Jeeves
- Developed scalable Node.js services using Docker and Jenkins to support back-end infrastructure.
- Wrote and optimized complex MySQL scripts for data processing and system reliability.
- Integrated APIs like DocuSign, Clickwrap, and Stripe to extend platform functionality and streamline workflows.
Technologies: JavaScript, Node.js, Express.io, MySQL, Jenkins, Docker, IntelliJ IDEA, Java
Senior Python Engineer
2021 - 2022
Vero
- Developed Python-based services with full Docker support.
- Provided production support, ensuring stable deployments.
- Integrated multiple providers like DocuSign and Firebase.
Technologies: Python, Django, MongoDB, MySQL, IntelliJ IDEA
Senior Java Developer
2018 - 2021
Conversocial
- Developed a graphical web for creating chatbots.
- Interacted with multiple social platforms, including Facebook, Instagram, Apple Business Chat, WhatsApp, and SMS.
- Programmed in multiple languages (Java, JavaScript, Node.js) and utilized various databases (MySQL, MongoDB).
Technologies: Java, JavaScript, IntelliJ IDEA, MongoDB, Docker, Instagram API, Facebook API, WhatsApp API
Senior Software Engineer
2017 - 2018
Assi.st
- Developed a graphical web user interface for creating chatbots.
- Interfaced with multiple social platforms, including Facebook, Instagram, Apple Business Chat, WhatsApp, and SMS.
- Programmed in multiple languages (Java, JavaScript, Node.js) and utilized various databases (MySQL, MongoDB).
Technologies: Java, Spring, MySQL, Scalability, JavaScript, Elasticsearch, Apache Tomcat, Hazelcast, API Development, API Design
Angular 2 Developer
2017 - 2017
Speerit.co
- Supported solutions for existing issues with a front-end project developed in Angular 2 using HTML5 and CSS3.
- Solved cross-browser issues in IE, Firefox, Chrome, and Safari.
- Used Git and IntelliJ for the IDE.
- Used VWO for A/B testing.
- Worked with most popular analysis websites for code optimization.
Technologies: CSS3, HTML5, Bootstrap, Hotjar, VWO, Angular
Angular 4 and Java Developer
2016 - 2017
ActitudRosario
- Created an entire website for back-end management of an eCommerce business.
- Created the administration site using Angular 4 and Java on the back-end with MySQL.
- Developed web scraping from multiple eCommerce sites (Amazon, Victoria's Secret, Carter's, GAP, Gymboree, etc.).
- Built image processing and conversion (adding water-marks, size, resolution, etc.).
- Converted product sizes for multiple countries.
- Tuned PROD builds using Gulp.
Technologies: MySQL, Angular, Spring, Java, Spring Boot
Senior Architect
2013 - 2014
Santa Fe Goverment
- Built an entire application framework for the Government of Santa Fe, based on EJB3/JPA2 and JSF2 (Primefaces).
- Built documentation standards for architecture, design, and configuration documents.
Technologies: Apache Maven, Jenkins, JBoss, GlassFish, Debian, Linux, Apache Velocity, XDoclet, JasperReports, Validation, jQuery, PrimeFaces, JPA 2, Hibernate, Spring 4, EJB3, Selenium, Apache JMeter, Checkstyle, FindBugs, SonarQube, CXF, Spring Boot
Senior Architect
2013 - 2013
DirecTV
- Developed new ETL processes using IBM DataStage.
- Evaluated and fixed bugs in existing processes.
- Built sequence and performance improvements.
- Provided project management support.
- Provided risk management.
Technologies: IBM InfoSphere (DataStage), ETL, Bash, PL/SQL, Java, Spring Boot
Senior Architect
2011 - 2012
Frávega
- Supported system analysts during inception and core process analysis.
- Made an enterprise architecture proposal.
- Developed device interfaces (electronic payment, ticket printers, barcode scanners, etc.).
- Distributed synchronization.
Technologies: EJB 3, COBOL, JAX-RS, JAX-WS, Swing, Java, Spring Boot
Senior Architect
2010 - 2011
Ledesma
- Initiated new processes and technologies within the company.
- Defined enterprise architecture.
- Made presentations to the client on topics like including architecture, operating models, etc.
Technologies: Service-oriented Architecture (SOA), Spring Boot
Technical Leader
2010 - 2010
Bank of Chile
- Coordinated a highly distributed team.
- Managed projects.
- Developed complex components.
Technologies: Web Services, Spring, Enterprise Java Beans (EJB), C, COBOL, IBM Db2, Oracle, GWT, Apache Struts, Spring Boot
Technical Leader and Senior Developer
2007 - 2010
Lowes.com
- Coordinated a high distributed team (four cities in Argentina and one city in the USA).
- Managed projects (staffing, planning, task assignation and monitoring, strategy, etc.).
- Led technical projects (architecture, design, estimations, complex functionalities development, etc.).
- Contributed to risk management.
- Communicated with the client and project managers in the USA.
Technologies: AppPerfect, Batch, Axis, Web Services, Endeca, Apache JMeter, Sybase, IBM Db2, IBM Commerce, Hibernate, Jakarta EE
Senior Developer
2007 - 2007
Jahia Community
- Developed and integrated a very flexible logging module, paying special attention in performance relative matters. Besides this development, a statistics module was developed for Jahia5 as an example of the logging module.
- Developed and adhered to object-oriented design.
- Wrote documentation.
- Created SVN patches.
Technologies: Jahia, Java
Senior Developer
2006 - 2007
OSDE
- Worked within a distributed team (four cities in Argentina).
- Designed, made estimations, and developed in Java.
- Communicated directly with the client.
Technologies: Batch, Apache JMeter, Hibernate, IBM Db2, Data Warehouse Design, Data Warehousing, Apache Struts, Jakarta EE
Software Analyst Level III
2005 - 2006
Central Bank of Uruguay
- Consulted on Tender customer support and advised the directors.
- Created contingency plans.
- Migrated systems.
- Created specification, design, and UML documentation.
Technologies: Web Services, Jakarta Server Pages (JSP), Servlet, Jakarta EE, UML
Software Analyst at SIIF Project
2001 - 2005
Ministry of Economy of Uruguay
- Analyzed, designed, and developed using ORACLE 8i tools.
- Gathered specifications.
- Generated modules using Oracle Designer.
- Developed stored procedures, triggers, and libraries using PL/SQL.
- Provided user support on application usage.
- Coordinated projects.
- Developed Java applets.
- Developed servlets in JSP and Core Java.
- Developed in PHP, C/C++/Pro-C, and VB.
- Designed websites.
Technologies: Reports, Forms, Tools, Oracle, C++, Visual Basic, PL/SQL
Experience
Speerit.co
Designed and developed a feature-rich Angular 2 application that seamlessly integrates with multiple social networks such as Facebook, Twitter, and LinkedIn. The platform enables users to manage posts, schedule content, track engagement metrics, and streamline multi-channel communication through a unified interface, enhancing user productivity and social media strategy execution across platforms.
Lowes.com
https://www.lowes.com/As a software developer and tech lead for Lowes.com, I managed projects and led a distributed team to design, develop, and optimize the website's functionality. This included improving user experience, integrating back-end services, ensuring scalability, and implementing features that enhanced retail sales, contributing to a more efficient and seamless online shopping experience for customers. Additionally, I collaborated with cross-functional teams to meet business requirements and deliver high-quality solutions.
Education
1995 - 2003
Degree in Software Engineering (Systems Engineering and Analysis)
Republic University - Montevideo, Uruguay
Skills
Libraries/APIs
Spring REST, Node.js, jQuery, JPA 2, JasperReports, JAX-WS, JAX-RS, Axis, API Development, Instagram API, Facebook API, WhatsApp API
Tools
Apache JMeter, JProfiler, Eclipse IDE, IntelliJ IDEA, Git, Cucumber, SonarQube, Checkstyle, XDoclet, Jenkins, Apache Maven, IBM InfoSphere (DataStage), Jahia, Servlet, Hotjar, Adobe Photoshop, Apache Tomcat
Languages
Java, SQL, Bash Script, Java 8, Bash, COBOL, C, Batch, UML, Visual Basic, HTML5, CSS3, C++, PHP, JavaScript, Python
Frameworks
Spring Security, Spring ORM, Spring, Spring Boot, JSF, Angular, AngularJS, Rational Unified Process (RUP), PrimeFaces, JUnit, Jasmine, CXF, Selenium, Spring 4, Hibernate, Apache Velocity, Swing, Apache Struts, GWT, Jakarta Server Pages (JSP), Bootstrap, Django, Express.io
Storage
Spring Data, Elasticsearch, PostgreSQL, PL/SQL, MySQL, IBM Informix, IBM Db2, MongoDB, Sybase, Spring Data MongoDB, Hazelcast, Redis
Paradigms
REST, Agile, ETL, Service-oriented Architecture (SOA)
Platforms
Oracle, Amazon Web Services (AWS), Android, Linux, Windows, Docker, Kubernetes, Apache Kafka, Debian, JBoss, Jakarta EE, Endeca, VWO, Amazon
Other
EJB 3, FindBugs, EJB3, Validation, GlassFish, Enterprise Java Beans (EJB), Web Services, IBM Commerce, AppPerfect, Data Warehousing, Tools, Forms, Reports, Data Warehouse Design, Scalability, API Design
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