William Barbosa
Verified Expert in Engineering
Full-stack Developer
Fortaleza do Tabocão - Tocantins, Brazil
Toptal member since February 24, 2022
William is a full-stack engineer with seven years of experience building highly scalable and maintainable software with notable clients, such as Pathfind, Recon Velocity, and O. C. Tanner. His primary expertise is in Java, React, and AWS technologies within the logistics, automotive, and employee recognition industries. William thrives in fast-paced environments while delivering high-impact products.
Portfolio
Experience
- Java - 7 years
- SQL - 5 years
- Spring Boot - 5 years
- JavaScript - 4 years
- Firebase - 3 years
- React - 2 years
- React Native - 2 years
Availability
Preferred Environment
Eclipse, IntelliJ IDEA, Visual Studio Code (VS Code)
The most amazing...
...thing I've created is a people tracking and counting system due to the deadline, technology used, and NP-hardness.
Work Experience
Full-stack Developer | FSL Contractor
O.C. Tanner
- Implemented and maintained the GraphQL and REST endpoints and subgraphs using Java in a microservices architecture.
- Migrated a Vue application to a React application following Figma design prototypes.
- Maintained Java JDK to be up-to-date with the latest versions, enhancing performance and scalability.
- Conducted error-checking and accuracy checks to ensure the Java codebase was according to the tickets' acceptance criteria, resolving any errors or other problems found.
- Migrated a Scala application to a Java application, keeping the business logic and adding support to Swagger.
- Tracked and fixed dependencies and vulnerabilities based on Snyk reports and dependency analysis.
- Implemented API pagination and refactored React to use pagination and debouncing, improving performance by 70%, and added new pages and features based on Figma designs.
- Created producers and consumers in Java and sink and source connectors to update downstream services.
Full-stack Developer | FSL Contractor
Recon Velocity
- Designed and implemented a routine to update the Recon’s time cached fields to improve performance and accuracy in a microservice architecture.
- Affected error-checking and accuracy checks to ensure the Java codebase was according to the tickets' acceptance criteria, resolving any errors or other problems found.
- Implemented REST endpoints, using Java in a microservices architecture.
- Added unit and integration tests to increase test coverage.
- Optimized JPA calls using hibernate logs and statics, minimizing databases calls and improving entities relationships.
- Refactored MongoDB queries to use Spring Data JPA Repository patterns for better maintainability and increased code implementation.
- Debugged application React app and improved interface software to improve functionality and performance by 20%.
- Optimizing React pages using pagination and debouncing approaches.
- Implemented new pages and features based on Figma designs.
Full-stack Developer
Pathfind
- Created an Apache image repository that contained 320,000 icons generated by image processing, reducing by 5% of the space consumed from all applications.
- Automatized the AWS servers with Python scripts, reducing up to 75% of the bill from servers on demand.
- Developed a Java algorithm to better use a truck according to weight, volume, cubage capacity, and the cost per mile, reducing the total cost of the route.
- Improved the customer experience by input validation, reducing call center problems reports.
- Refactored Java code, detected bottlenecks, and improved pages and routines, gaining up to 20% of performance.
- Maintained the functionality and stability of the Pathfind servers at AWS—EC2, load balance, RDS, and S3.
- Analyzed and designed the system requirements elicitation while satisfying customers' needs with 80% acceptance rates.
- Applied shell and SQL scripts to back up and clean massive databases, gaining up to 90% of performance.
Full-stack Developer
Gestorama Self-employed
- Developed a real-time chat, a filesystem, and a user auth designed UI with Figma and implemented CRUD, using database NoSQL from Firebase Firestore.
- Developed a multi-platform app with all services based on the serverless paradigm.
- Implemented Payment Service with TypeScript, using CloudFunctions to consume the Juno Payment API.
- Implemented high scalability with a React Native mobile app, using Firestore, storage, Authentication, Crashlytics, performance, and Cloud Messaging services.
- Implemented store for data management using Redux and Redux Thunk.
Experience
Problem-Solving Skills
https://github.com/williampmb/problem-solving-skillsAlgorithms and data structures are from different websites such as LeetCode, Codacy, and HackerRank, building a repository to tackle problems and optimize them. Issues are related to binary search, arrays, strings, dynamic problems, hash tables, trees, and graphs.
Warehouse Serverless API
https://github.com/williampmb/warehouse-awsThe API Gateway receives the requests and passes them to Lambda functions to process and save in the S3 bucket. All functions are coded with Java.
Gestorama
The payment process is managed inside the app with the Juno Payments API. The app is 100% serverless using Firebase with Firestore, cloud functions, and Firebase storage.
General Byzantine
https://github.com/williampmb/GeneralByzantineEducation
Specialization in Computer Science
Estacio - Fortaleza, CE, Brazil
Bachelor's Degree in Computer Science
State University of Ceara - Fortaleza, CE, Brazil
Exchange Program in Computer Science
University of Wisconsin—La Crosse - La Crosse, WI, USA
Exchange Program in Intensive English
University of Washington - Seattle, WA, USA
Bachelor's Degree in Mathematics
State University of Ceara - Fortaleza, CE, Brazil
Skills
Libraries/APIs
React, Vue, Node.js
Tools
IntelliJ IDEA, Flyway, Jenkins, Papertrail, Postman, Jira, Figma, Git, Crashlytics, Apache Maven
Languages
Java, JavaScript, SQL, GraphQL, TypeScript, CSS, HTML
Frameworks
React Native, Spring Boot, JPA, Hibernate, Spring, OAuth 2
Paradigms
Microservices Architecture, REST, Microservices, Parallel Programming, Mobile Development
Storage
PostgreSQL, MongoDB, MySQL, Google Cloud, Amazon S3 (AWS S3), Cloud Firestore, NoSQL, Elasticsearch
Platforms
Firebase, AWS Lambda, Eclipse, Amazon EC2, Apache Kafka, Amazon Web Services (AWS), Visual Studio Code (VS Code), LeetCode
Other
APIs, Mathematics, Algorithms, Data Structures, Serverless, API Gateways, Amazon RDS, Storage, Firebase Cloud Functions, API Integration, User Roles, Reactive Streams, Dependency Analysis
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