Fernando Melo, Developer in São Paulo - State of São Paulo, Brazil
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Fernando Melo

Verified Expert  in Engineering

Back-end Developer

São Paulo - State of São Paulo, Brazil
Toptal Member Since
October 27, 2022

Fernando is a software developer with 10+ years of experience building and integrating eCommerce platforms with ERPs and rewards systems. Skilled in several technologies, programming languages, and frameworks, he specialized in Java with Spring Boot, MongoDB, and ElasticSearch. Fernando is a lifelong learner, willing to leverage his experience in new projects and start delivering value and results.


Java, MongoDB, Elasticsearch, InfluxDB, Helm, Azure Cloud Services, Redis...
Node.js, PostgreSQL, Express.js, Sequelize, REST, Web Crawlers, Programming
.NET, .NET 4, jQuery, HTML, CSS, SQL, SQL Server 2008, SQL Server 2008 R2...




Preferred Environment

Linux, Slack, IntelliJ IDEA, Spring Boot

The most amazing...

...API I've developed helps users find the best place to buy the products in their shopping cart from a set of 200+ possible stores and warehouses.

Work Experience

Lead Back-end Developer

2015 - PRESENT
  • Developed a logistics API to find the best origin of the products in the customers' shopping cart from a set of more than 200 possible stores and warehouses.
  • Created monitoring dashboards for several microservices with information about request count, response time, business information, and HTTP status for each endpoint and its dependencies.
  • Built a search engine used by a product comparison tool that covers almost all of the Brazilian eCommerce market.
  • Developed a low code tool to create integrations between eCommerce platforms and ERP systems.
Technologies: Java, MongoDB, Elasticsearch, InfluxDB, Helm, Azure Cloud Services, Redis, RabbitMQ, Spring Cloud, Spring Cloud Sleuth, Git, Kanban, Objectives & Key Results (OKRs), ELK (Elastic Stack), JUnit, Programming, Microservices, Java 11, Java 8, Python, Mockito, RESTful Microservices, Microservices Architecture, API Integration

Lead Back-end Developer

2014 - 2014
  • Created the API for an app that allows users to provide and consult beer reviews.
  • Built an automated crawler to quickly start the app database while there were few user reviews.
  • Modeled the database with full-text search capabilities to create the API search engine.
Technologies: Node.js, PostgreSQL, Express.js, Sequelize, REST, Web Crawlers, Programming

Full-stack .Net Developer

2012 - 2014
  • Fixed bugs in existing functionalities and implemented new, small functionalities for the Brazilian version of the eCommerce website of Walmart.
  • Helped maintain and extend the administrative back office for the B2B arm of Walmart's eCommerce.
  • Implemented the layout for different partners that used the B2B website, changing the style from the original to a version with the partner's colors and brands while maintaining all the functionality.
  • Created the engine for a prize draw system using results from the official Brazilian lottery (Loteria Federal) as a reference.
Technologies: .NET, .NET 4, jQuery, HTML, CSS, SQL, SQL Server 2008, SQL Server 2008 R2, Scrum, NHibernate, Visual Studio, Visual Studio Team Services (VSTS), Programming, ASP.NET, ASP.NET MVC, Relational Databases

Full-stack .Net Developer

2009 - 2011
The Planet Group
  • Fixed front- and back-end bugs on a website using Sitefinity CMS eCommerce.
  • Created custom controls integrated with the Sitefinity CMS and Telerik.WebControls to be dragged and dropped on the CMS.
  • Created a tool to help migrate between environments (between different instances) of Sitefinity CMS before the platform provided a tool to do this.
  • Implemented custom business logic in the back end to adapt the system to the client's needs.
  • Created multiple portals with Sitefinity CMS for clients that needed a reward system for their sellers inside their CMS (HP, Fujitsu, Microsoft, and Symantec).
Technologies: .NET, .NET 2, Sitefinity, Telerik Web Controls, SQL, SQL Server 2008, SQL Server 2008 R2, JavaScript, HTML, CSS, jQuery, Visual Studio, TortoiseSVN, Full-stack, Full-stack Development, Relational Databases

Delivery Method Broker

Created a set of microservices that allowed a Brazilian fashion retailer to sell all the products from its more than 200 stores and warehouses online throughout the country.

I started as the back-end developer, and then as the project evolved, I was responsible for designing the architecture and business rules. With my comprehensive knowledge of the project, I became the natural lead developer, guiding three other developers in adding new features and optimizing existing ones.

The main API would split the shopping cart into different parts if necessary to use the best-located origins available, considering the customer's location, stores with more items available, the stores' capacity to fulfill the order, delivery price, etc.

It was created to be multi-country and multi-brand. It is used in Brazil and Uruguay but built to be flexible for adoption in other countries. It is also used in Brazil by other brands of the same company, but it was created to eventually be packaged and sold in a SaaS-like format to any other eCommerce business.

Price Comparison Search Engine

Built an API that allows customers to search all the products covered by a price comparison tool and view their prices in many different eCommerce businesses and marketplaces of the Brazilian market.

It has an indexing service running job to index the product catalog and price information into ElasticSearch, reading from a SQL Server database. It also has a querying service to get the data from ElasticSearch based on the words typed in the search box and filters applied.

I designed mappings, word analyzers, and search queries for ElasticSearch and was also one of the back-end developers of the Java API.

Android App for a Smart POS Terminal - Credit Card payment

Created an Android app to receive payments for a drugstore chain using a Smart POS terminal. The app was integrated with the store's sale system to know the payments that needed to be made and to return the status of those payments.

It was implemented to use both the Wi-Fi network and the mobile network. That way, the store could still sell and receive payments even if the cable internet connection had a problem. The store's sale system can communicate with the POS through Wi-Fi because the local network is still working and only missing the internet connection. The Smart POS can communicate through the mobile network with the payment processing system.

Prize Draw System | Hotel Chain Marketing Campaign

Created the engine for a prize draw system using the results from the official Brazilian lottery (Loteria Federal) as a reference. The campaign was intended to stimulate sales promoters. They received coupons based on their sales. There were many rounds for the prize drawing and rules to establish how the prizes would be drawn. There was nothing random that allowed the picture to be audited.

Magento eCommerce for Selling OOH Ads in Elevators/Lifts

Helped build a Magento ECommerce application customized to selling OOH (Out of Home) ad space on elevators/lifts. I was initially involved in the project thanks to my Elasticsearch experience. I customized the query used by a Magento Elasticsearch plugin to allow users to search available spots based on location (filter closest, filter by neighborhood, city, state, etc.). I had to create the front end to display this customized search result, including showing the results using a map. It allowed the customer to buy a slot in a specific building or many slots across a big region.

I also created an auxiliary application using PhalconPHP that allowed customers to upload their ad content. It was integrated with the Magento application to allow only registered users in the Magento database to list purchases.

API to Help Analyze Medical Bills to Spot Improper Billing

Created an API and search engine used by a health insurance company to review hospital bills in search of improperly billed items. It allowed the reviewers to easily search multiple PDF files to check the regulations and norms enforced on a specific date.

These files were read and indexed to Elasticsearch. With the adoption of the API, every review and conclusion began to be recorded to an SQL server and indexed to Elasticsearch. This allowed reviewers to see that a similar medical bill had been reviewed before. The reviewer will then save time by checking if it's the same scenario, and they can use the same conclusion for their bill.
2009 - 2012

Associate's Degree in Digital Games

Faculty of Technology of Sao Caetano do Sul - Sao Caetano, SP, Brazil


Spring Cloud Sleuth, REST APIs, jQuery, Node.js, Vue


Git, Postman, Slack, IntelliJ IDEA, Helm, RabbitMQ, ELK (Elastic Stack), Sequelize, Grafana, Azure Kubernetes Service (AKS), Cron, Gatling, Gatling Load Testing, Jenkins, Eclipse IDE, Apache JMeter, Gradle, Android Studio, GitLab, Visual Studio, Apache Tomcat, Sitefinity, TortoiseSVN, Java Development Kit (JDK)


Unit Testing, REST, Microservices, Microservices Architecture, Kanban, Objectives & Key Results (OKRs), Automated Testing, Scrum


Spring Boot, Spring, .NET 4, ASP.NET, ASP.NET MVC, ASP.NET MVC 4, Mockito, JUnit, Express.js, Swagger, .NET, PhalconPHP, Bootstrap, NHibernate, .NET 2


Java, Java 11, SQL, JavaScript, Java 8, PHP, CSS, HTML, Python


Elasticsearch, Relational Databases, MongoDB, InfluxDB, MySQL, SQL Server 2008 R2, Azure Cloud Services, Redis, PostgreSQL, SQL Server 2008, Realm, Microsoft SQL Server


Linux, Kubernetes, Amazon Web Services (AWS), Amazon EC2, New Relic, Eclipse, Android, Magento, Visual Studio Code (VS Code), Oracle


Programming, Integration Testing, Web Development, Spring Cloud, APIs, Geolocation, RESTful Microservices, API Integration, 3D Modeling, Web Crawlers, Back-end, Jobs, Logistics, Delivery, WSO2, WSO2 API Manager, Payment APIs, Card Payments, Mobile Payments, NanoHTTPD, Lottery, Full-stack, Visual Studio Team Services (VSTS), Telerik Web Controls, Full-stack Development

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