Juan Roldan, Developer in Singapore, Singapore
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Juan Roldan

Verified Expert  in Engineering

APIs Developer

Location
Singapore, Singapore
Toptal Member Since
June 23, 2020

Juan is a highly-motivated senior software engineer who has worked as a Java and back-end developer for the past 5+ years. He held a key role as a team leader, planning, developing new products, and mentoring people. He was the first in his class at the best IT Spanish university, so he has extensive technical knowledge. Juan enjoys working in agile environments and is a team player with excellent communication and social skills; he is also methodic, precise, and perfectionist.

Portfolio

ABN AMRO Bank
Java, Python, Amazon Web Services (AWS)
Leaseplan
Java, Microservices, Leadership, Architecture, Amazon Web Services (AWS)...
Backbase
Amazon Web Services (AWS), Spring Boot, SQL, Git, Kubernetes, Docker...

Experience

Availability

Part-time

Preferred Environment

Skype, Email, Git, Slack

The most amazing...

...project I've contributed for is the Campaign Manager, a product which enables marketers to create marketing campaigns based on data collected by banks.

Work Experience

Lead Back-end Developer

2022 - PRESENT
ABN AMRO Bank
  • Changed the process within the team to improve our performance and be able to reach the deadlines.
  • Designed and implemented a solution to fulfill the European regulations.
  • Improved the quality of the project, making it scalable and maintainable.
Technologies: Java, Python, Amazon Web Services (AWS)

Lead Software Developer

2021 - PRESENT
Leaseplan
  • Improve the application's architecture to move from an MVP to a production-ready solution available in several countries.
  • Lead and mentored team members on the product and the best programming practices.
  • Worked in the SCRUM team, delivering every sprint with more than what was committed.
Technologies: Java, Microservices, Leadership, Architecture, Amazon Web Services (AWS), Amazon Simple Queue Service (SQS), Kubernetes

Lead Softwre Engineer

2019 - 2021
Backbase
  • Contributed to making a production-ready application from a proof of concept, led part of the technical change, and made technical decisions in every product development phase. This software is now being actively used.
  • Migrated some of our pipelines to Jenkins and Kubernetes, chose the versioning strategy and pipeline structure. Ultimately this became a model to follow for the tribe.
  • Served as a high-performing key developer in my department.
Technologies: Amazon Web Services (AWS), Spring Boot, SQL, Git, Kubernetes, Docker, Apache Maven, Spring, Java, Leadership, Architecture, Node.js, React

Senior Software Engineer

2017 - 2018
European Patent Office
  • Worked with a Spring boot application that based the workflow in the BPM engine.
  • Improved the productivity of the front-end team, and led the team to develop an application to allow uploads of zip files with different sites to test live. It proved to be a success.
  • Participated and contributed to the architecture and designing of the most ambitious project in the company at the moment.
  • Contributed to the decision of which database to use.
  • Joined as a software maintainer and promoted to become the main developer and owner for three out of the seven services of the platform in less than a year.
Technologies: MongoDB, Jenkins, Microservices, JBoss, Apache Maven, Spring, Java

Senior Back-end Developer

2017 - 2017
Sngular
  • Proposed, created, and implemented a library that was proven to reduce a lot of the development time of the projects we were building.
  • Completed all the tasks in significantly less time than expected, creating a lot of opportunities to help other team members.
  • Introduced more strict control in the code review process that ultimately improved the coding quality standards of the team and noticeably reduced the number of bugs.
  • Developed software integration with Amazon SES and SQS.
Technologies: MongoDB, Docker, Spring, Java

Junior Back-end Engineer

2016 - 2017
LINE Plus
  • Communicated effectively as a member of a team with only Korean people, who mainly spoke in Korean, and successfully made big software improvements.
  • Implemented concurrency in a non-concurrent system which eventually would publish some code to millions of devices.
  • Found and fixed a bug in an SQL query which was blocking the server and causing major issues in the platform.
Technologies: Redis, MyBatis, JavaScript, Java

Campaign Manager

Campaign Manager enables marketers to create marketing campaigns based on data collected by the bank.

I was involved from the beginning, ultimately creating a production-ready application whilst being the most senior developer on the team.

Real Estate Aggregator

Bluggie Real Estate crawls and aggregates data from several rental websites in the Netherlands, presenting them through a common interface to seeking tenants.

The application was built using data engineering techniques to improve the search process.

Web Crawler Framework

I created a framework to perform web crawling in a Java-like Scrapy done in Python.

This framework was well tested and is especially useful for some of my personal projects.

The framework also exposed a REST API to check the status of the crawling.

Reselling Platform

This is an application focused on reselling goods in bulk. The platform supported up to 2000 transactions/second with three server instances.

I designed and implemented the contract-first API using OpenAPI and solved many concurrency problems in Java.
2012 - 2015

Bachelor's Degree in Software Engineering

Polytechnic University of Madrid - Madrid, Spain

Libraries/APIs

REST APIs, Node.js, React, MyBatis, OpenAPI

Tools

Jenkins, Git, Apache Maven, Apache JMeter, Amazon Simple Queue Service (SQS)

Frameworks

Spring, Spring Boot, Flask, Scrapy, Hibernate

Languages

Java, SQL, Python, JavaScript 6, TypeScript, Solidity, JavaScript

Paradigms

DevOps, Microservices

Platforms

Docker, Kubernetes, Google Cloud Platform (GCP), Ethereum, Blockchain, JBoss, Amazon Web Services (AWS), Apache Kafka

Storage

MongoDB, PostgreSQL, NoSQL, Redis, MySQL

Other

Web Crawlers, Cryptocurrency, IT Consulting, Performance, APIs, Architecture, Leadership, Smart Contracts, Concurrency

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