Oscar is available for hire
Hire OscarOscar Guindzberg
Verified Expert in Engineering
Lean Development Developer
Location
Buenos Aires, Argentina
Toptal Member Since
February 11, 2014
Oscar is a software engineer with 15+ years of experience in the UK and Argentina. He is a Bitcoin & Java expert, co-founder of CreationFlow, and a former university object-oriented design teacher.
Portfolio
Doosra
Bitcoinj, Android
Strawpay
Cryptocurrency Payments, Bitcoin, Android
37coins
HD Wallets, Multisig, Blockchain, Bitcoinj, Bitcoin
Experience
Availability
Part-time
Preferred Environment
Heroku, Apache Maven, Git, Eclipse
The most amazing...
...thing I've built is CreationFlow, a tool for online collaboration, proofing, review, and approval for digital art production.
Work Experience
Bitcoin Developer
2015 - PRESENT
Doosra
- Made Doosra's hardware wallet work with Andreas Schildbach Android bitcoin wallet.
Technologies: Bitcoinj, Android
Bitcoin Developer
2015 - 2015
Strawpay
- Implemented Strawpay's Stroem protocol on Andreas Schildbach Android bitcoin wallet.
Technologies: Cryptocurrency Payments, Bitcoin, Android
Bitcoin Developer
2014 - 2015
37coins
- Developed a REST API based on top of the blockchain.
Technologies: HD Wallets, Multisig, Blockchain, Bitcoinj, Bitcoin
Open Source Developer
2014 - 2014
Nimblecoin
- Created the reference node code for NimbleCoin.
- Contributed to BitcoinJ.
- Implemented a missing feature in BitcoinJ to work as a full node.
- Ran performance tests.
- Implemented a reference miner.
Technologies: Java, Bitcoinj, Bitcoin
Software Developer
2011 - 2014
Freelance
- Created a recommendation engine that uses the social graph.
- Created a website and its profitable AdWords campaign in 40 hours.
- Connected AdWords API and Twilio API.
- Created a web interface to a complex Excel spreadsheet.
- Deployed from home to IBM server not accesable from the internet.
- Hacked the Facebook API to get the friend list of your friends.
- Beta tested Spring Social and reported bugs.
- Implemented a Flash visual tool to modify SVG files.
- Modified and installed a penny auction script.
Technologies: Amazon EC2, Amazon S3 (AWS S3), Heroku, Git, Eclipse, JUnit, Selenium, PHP, Linux, Play Framework, CSS, HTML, Apache Struts, Aspose Components, jQuery, Jakarta Server Pages (JSP), Apache Tiles, Logback, Jackson, PostgreSQL, Apache Tomcat, Hibernate, JPA, Apache Maven, Spring Social, Spring MVC, Spring Security, Spring, Java
Open Source Node.js Developer
2013 - 2013
DemocracyOS
- Created a user-friendly, open-source, vote-and-debate tool, specially crafted for parliaments, parties, and decision-making institutions that allow citizens to get informed, join the conversation and vote on topics, and adjust how they want their representatives to vote.
- Transformed the noise that protesters create into a signal that has a clear, direct, and strong impact on the political system.
- Worked towards the DemocracyOS vision of becoming the operating system serving open and participatory governments.
Technologies: Amazon S3 (AWS S3), Heroku, Git, Page.js, JADE, Mongoose, MongoDB, Passport.js, NPM, Express.js, JavaScript, Node.js
Co-founder
2007 - 2011
CreationFlow
- CreationFlow is the online collaboration, proofing, review, and approval tool for digital art production. CreationFlow lets you get accurate feedback on work-in-progress design pieces (images, videos, pdf, etc) without the hassle of emails, ftp, and phone feedback. Users can upload files and let others suggest changes using built-in mark-up tool. Raised a $150k seed round.
- Programmed CreationFlow's MVP.
- Ran a PR campaign that got us featured on the New York Times: http://goo.gl/cRv5J.
- Gave webinars that got us clients in 13 different countries.
- Decided to pivot and throw away 1-year-work code.
Technologies: Eclipse, Hibernate, MySQL, Flex, Java
Software Contractor
2006 - 2007
Royal Bank of Canada
- Implemented statistical analysis software (econometrics/cointegration) over historical/real-time stock prices.
- Connected to the Reuters API to retrieve real-time stock quotes.
Technologies: Eclipse, Subversion (SVN), Selenium, jMock, JUnit, Apache Maven, Java
Senior Java Developer
2004 - 2006
Lastminute.com
- Helped establish offshore development team in Argentina.
- Redesigned the site layout and content to improve SEO.
- Implemented a solution for the form resubmition problem in the Hotels section.
Technologies: Eclipse, Apache Velocity, JDBC, Ant Design, Linux, JBoss, Apache Struts, Java
Project Manager, Architect, Training Manager, Technical Interviewer
2004 - 2006
Globant
- Recruited 5 of my university students to work for Globant.
- Created the training area in the company. Organized dozens of tech seminars.
- Interviewed and evaluated Java developers candidates.
- Worked on “Mobile Bid system” for Boldt Argentina (http://www.boldt.com.ar). Directed the development of a bid application system for cell phones.
- Coordinated a group of 2 senior developers.
Technologies: Java
University Professor
2003 - 2006
National Technological University
- Lectured more than 300 students over 3 years.
- Created course content and exams used by myself and other professors.
Technologies: Automated Testing, Multithreading, Design Patterns, Object-oriented Analysis & Design (OOAD)
Java Developer
2001 - 2004
EDS
- Implemented the first corporate online banking system in Latin America. EDS is one of the biggest information technology services and solutions company worldwide.
- The project was the re-engineering of an on-line fund-transfer system from Cobol/CICS to a web-based application. Worked on this project since the beginning. Tasks included front-end and back-end development. For the front-end we used Struts, JSP, and custom tag libraries. In the back-end we used a Services Oriented Architecture, JMX, EJB, and JMS.
- Was one of the first users of Struts and EJB in Argentina.
Technologies: WebLogicServer, Apache Tomcat, JMS, Enterprise Java Beans (EJB), JMX, Jakarta Server Pages (JSP), Apache Struts, Java
R&D Java Developer
2000 - 2001
Soluciones Integrales
- The ERP is designed in 3-tier and fully developed in Java. The front-end is Swing and uses a persistence framework developed by Soluciones Integrales. Task consisted of doing research in Java technologies and to inform the results that could add value to the ERP. Recommended JSDT to program a chat, then Servlets/JSP to give a web-interface to some parts of the application and finally WML to make it compatible for portable devices like PDAs or cell phones.
Technologies: Servlet, Swing, Java
Developer
1999 - 2000
Decidir.com
- Decidir.com is a website that gives commercial risk information (i.e. rejected checks, trials, debts). It also has an online credit card validation system.
- Initially developed the billing system using Access 7.0. Since it was a small application, was responsible for all the analysis, design, and development. When the company grew, the CTO decided to buy SAP R/3, then was responsible for the data migration from the small bill system to SAP R/3 and end-user training & support. Made first incursion in Java world, developing the online credit card validation system which consisted of a few Servlets and HTML pages.
Technologies: Servlet, Java, SAP, Microsoft Access
Trainee
1997 - 1999
Maer Software
- Maintained up-to-date the already developed systems.
- Gave in person and on phone support to end users.
Technologies: Visual FoxPro, Microsoft Access
Experience
DemocracyOS
https://github.com/DemocracyOS/appOnline voting platform developed in Node.js: http://democracyos.org/
Live: http://dos.partidodelared.org/
Live: http://dos.partidodelared.org/
Votamos Todos
Experimental online poll system developed in PHP with Facebook API.
JuicyCanvas
Website for discovering and customizing contemporary art using Java and Flex.
Find singles
Experimental site for finding single guys/girls within your Facebook friends and friends' friends. Built in PHP with Facebook API.
CreationFlow
The startup I co-founded. An online collaboration tool for graphic designers.
Blog for Parents
Did everything from technology to promotion (minus content). The website helped my partner (a psychologist) to increase her number of patients from 0 to 20 and got her on TV.
Skills
Languages
Java, HTML, JavaScript, JADE, Visual FoxPro, PHP, CSS
Frameworks
Jakarta Server Pages (JSP), Spring MVC, Spring, Spring Security, Selenium, Apache Struts, Adobe Flex, JUnit, Flex, Ant Design, Apache Velocity, Express.js, Swing, Hibernate, Java Agent DEvelopment (JADE), Play Framework, Apache Tiles, JPA
Tools
Spring Social, GitHub, Eclipse IDE, Subversion (SVN), Git, Apache Maven, Apache Tomcat, WebLogicServer, Microsoft Access, NPM, Servlet, Apache Ant, Mongoose
Paradigms
Model View Presenter (MVP), Object-oriented Programming (OOP), Agile Software Development, Design Patterns, Object-oriented Design (OOD), Unit Testing, Object-oriented Analysis & Design (OOAD), Automated Testing, Test-driven Development (TDD), Test Automation, Scrum, Extreme Programming, Continuous Integration (CI)
Other
Lean Development, Bitcoin, Logback, Page.js, SAP, Bitcoinj, Multisig, HD Wallets, Cryptocurrency Payments, Ajax, Multithreading, Enterprise Java Beans (EJB)
Libraries/APIs
Facebook API, jQuery, Aspose Components, JMX, JMS, Passport.js, Node.js, JDBC, Jackson, jMock, jQuery UI
Platforms
Heroku, Eclipse, JBoss, Blockchain, Android, MacOS, Windows, Amazon EC2, Linux
Storage
MongoDB, Amazon S3 (AWS S3), MySQL, PostgreSQL, JSON
Education
1997 - 2001
Bachelor's Degree in Software Engineering
National Technological University - Buenos Aires, Argentina
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