Elder Santos, Developer in São José dos Campos - State of São Paulo, Brazil
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Elder Santos

Verified Expert  in Engineering

Full-stack Software Engineer and Developer

São José dos Campos - State of São Paulo, Brazil
Toptal Member Since
March 13, 2013

Elder is an accomplished full-stack software engineer. From startups to enterprise ventures, his journey has been marked by a trail of successes. Elder has expertise in the full lifecycle of the software design process, including requirement specifications, prototyping, proof of concept, implementation, testing, and maintenance.


Joinesty, Inc.
Amazon Web Services (AWS), Angular, React, Node.js, TypeScript, Python...
Andrew Koudijs
JavaScript, Web Development, CSS, HTML, HTML5, Technical Leadership...
Toptal Clients
Go, React, Node.js, TypeScript, Amazon Web Services (AWS), Elasticsearch...




Preferred Environment

MacOS, Windows, Visual Studio Code (VS Code), Linux, Visual Studio

The most amazing...

...project I've created was an aircraft maintenance program connected to the 1553 bus protocol. It uses enhanced shortest path algorithms and system optimizations.

Work Experience

Lead Software Engineer

2016 - PRESENT
Joinesty, Inc.
  • Created the whole cloud infrastructure and defined the stack for the back end and front end to support thousands of clients.
  • Managed the development team. Talked with stakeholders and investors about product road map and deliverables.
  • Designed and built a solution to store sensitive data from customers.
Technologies: Amazon Web Services (AWS), Angular, React, Node.js, TypeScript, Python, .NET Core, Microsoft SQL Server, C#, Architecture, Front-end, Back-end, Azure, PostgreSQL, CTO, SaaS, Google Cloud Platform (GCP), APIs, Amazon EC2, gRPC, Solution Architecture, Programming, Distributed Systems, Docker, App Infrastructure, Cybersecurity, PCI, PCI Compliance, PCI DSS, Agile Project Management, Cloud Architecture, Engineering

Lead Developer (via Toptal)

2021 - 2024
Andrew Koudijs
  • Acted as a tech lead, defining and implementing the whole architect on the back end and front end.
  • Designed and implemented an inventory and eCommerce system for cannabis retail and wholesale.
  • Improved the internal and external logistics process, accelerating the lead time from cultivation to sales.
Technologies: JavaScript, Web Development, CSS, HTML, HTML5, Technical Leadership, Architecture, Web Architecture, Next.js, Go, Amazon Web Services (AWS), Swift, Mobile, Agile Project Management, Cloud Architecture, Engineering

Software Developer

2013 - 2021
Toptal Clients
  • Designed and developed a web proxy filter in Go. The product was composed of a web proxy plus a web administration tool. Both components were written in Go.
  • Developed the filter according to the required RFCs and implemented the best security practices.
  • Contributed to gathering interest from big players in the data loss prevention industry.
Technologies: Go, React, Node.js, TypeScript, Amazon Web Services (AWS), Elasticsearch, Docker, Bootstrap, jQuery, GraphQL, Python, Django, Flask, Next.js, C#, SQL, Software Architecture, SaaS, Multitenancy, APIs, Solution Architecture, Amazon DynamoDB, Programming, CI/CD Pipelines, Testing, FFmpeg, Code Review, Engineering

Technical Lead

2008 - 2016
  • Supported the software engineering team with technical decision-making.
  • Worked as a senior developer in the .NET platform.
  • Handled the development of applications related to financial products.
  • Maintained old and outdated C# projects for customers around the world.
  • Updated a legacy application using ASP.NET MVC, C#, JavaScript, MVVM, and Twitter Bootstrap, releasing an entirely new version.
Technologies: Amazon Web Services (AWS), Oracle, Dapper, NHibernate, Entity Framework, Microsoft Silverlight, Azure, JavaScript, Windows Communication Foundation (WCF), Windows Presentation Foundation (WPF), PostgreSQL, PL/SQL, T-SQL (Transact-SQL), C#, SaaS, Multitenancy, APIs, Solution Architecture, Programming, Docker, CTO, Code Review, Project Management

Technical Lead

2007 - 2008
Microsoft Innovation Center
  • Handled technical requirements in interop projects.
  • Developed cross-platform software for Windows and Linux.
  • Worked with the most up-to-date Microsoft technologies, including Silverlight, WPF, WCF, and WWF.
  • Researched the local market and provided training for locals.
  • Supported local companies with technologies like Microsoft Silverlight, WPF, WCF, WWF, and SQL Server.
Technologies: Microsoft Silverlight, Windows Communication Foundation (WCF), Windows Presentation Foundation (WPF), WWF, Java, Linux, Oracle, Microsoft SQL Server, SharePoint, VB.NET, C#, SQL Server BI, Software Architecture, Solution Architecture, Distributed Systems, Mobile

Solution Archtect

2007 - 2008
Onset Technologies
  • Provided interoperability between .NET and Ruby applications.
  • Analyzed software requirements and provided solutions based on the Microsoft platform.
  • Solved business problems with solutions architected under the .NET platform and other Microsoft products.
  • Managed internal and external projects using Microsoft SharePoint technologies.
  • Created a global application for Johnson&Johnson to monitor all their other applications (including ERP) around the world.
Technologies: SharePoint, C++, VB.NET, MySQL, Oracle, Microsoft SQL Server, C#, ASP.NET, ASP.NET MVC, jQuery, App Infrastructure

Sony Ci

Sony's Ci Media Cloud expands into cloud-native asset management. With the addition of a catalog, Ci provides content owners, studios, production companies, broadcasters, sports leagues, music labels, and large corporations with a comprehensive system that supports content management.

SPL Fiscal

A web application written in ASP.NET using NHibernate to handle ORM communication with SQL Server and Oracle databases. The app is used to generate digital files dynamically according to user configurations.

It includes a great background execution process to analyze data and yield results in different formats.

Joinesty Password Manager

A web-based and browser extension application to manage passwords and secret notes over different devices and share them with team workers. It is hosted on AWS and uses several services from that. The core back end is in Go and the front end is TypeScript with React.
2014 - 2016

Master's Degree in Artificial Intelligence

Federal University of São Paulo - Sao Jose dos Campos

2008 - 2012

Bachelor's Degree in Computer Science

Federal University of São Carlos - Sao Carlos, Brazil


Microsoft Certified Technology Specialist



Microsoft Certified Dynamics Specialist



Microsoft Certified Application Developer



Microsoft Certified Systems Administrator:



Microsoft Certified Database Administrator



Microsoft Certified Solution Developer



REST APIs, Node.js, jQuery, jQuery UI, React, Entity Framework, Vue, Facebook API, LinkedIn API, X (formerly Twitter) API, Backbone.js, Instagram API, NumPy, FFmpeg


GitHub, Sublime Text, Microsoft Visual Studio, Amazon Elastic Container Service (Amazon ECS), Mercurial, TextMate, LINQ to SQL, Subversion (SVN), RabbitMQ, Microsoft Silverlight, Dapper, Azure Kubernetes Service (AKS), Visual Studio, AWS Key Management Service (KMS), Webpack, Amazon Simple Queue Service (SQS), Amazon Simple Notification Service (Amazon SNS), Microsoft Project, Emacs, Microsoft Team Foundation Server, Amazon Athena, Jira, AWS CodeBuild, AWS Glue, DataViz, SQL Server BI


Flask, .NET, ASP.NET MVC, Windows Presentation Foundation (WPF), AngularJS, Django, Express.js, Entity, Bootstrap, NHibernate, ASP.NET Web API, ADO.NET, WWF, .NET Core, Angular, ASP.NET, Knockout (Knockout.js), Hadoop, Spark, AWS HA, Next.js, gRPC


Go, Python, SQL, JavaScript, C#, HTML, C#.NET, R, C++, HTML5, TypeScript, CSS, GraphQL, Visual Basic 6 (VB6), Less, T-SQL (Transact-SQL), VB.NET, Java, C, F#, Snowflake, Python 3, Swift


Microservices, Object-oriented Programming (OOP), Agile Software Development, Functional Programming, Procedural Programming, Design Patterns, Microservices Architecture, Testing, Agile Project Management, COM+, Distributed Computing, Parallel Computing, Database Design, Web Architecture, API Architecture, REST, REST API Architecture, ETL, Requirements Analysis


Amazon Web Services (AWS), Windows, AWS Lambda, Docker, Amazon EC2, Linux, Oracle, Software Design Patterns, SharePoint, Azure Functions, Azure IaaS, Ubuntu, Visual Studio Code (VS Code), iOS, MacOS, Azure, Kubernetes, Google Cloud Platform (GCP), Apache Kafka, Mobile


MongoDB, Microsoft SQL Server, Relational Databases, JSON, NoSQL, PostgreSQL, Amazon S3 (AWS S3), Amazon DynamoDB, PL/SQL, Redis, Elasticsearch, SQL Server 2012, Azure SQL, MySQL, SQLite, Redshift, Apache Hive, Data Lakes, AWS Data Pipeline Service, Databases

Industry Expertise

Cybersecurity, Project Management


CTO, Machine Learning, Full-stack, Architecture, Back-end, Web Scraping, Amazon RDS, SaaS, APIs, Business Architecture, Enterprise Architecture, Solution Architecture, Web Applications, Programming, Back-end Development, App Infrastructure, Technical Leadership, Windows Communication Foundation (WCF), Data Engineering, Software Architecture, Software Design, Multitenancy, Multithreading, .NET 6, Distributed Systems, CI/CD Pipelines, Code Review, Cloud Architecture, Engineering, COM, Amazon Kinesis, Crypto, Elastic Load Balancers, Leadership, ETL Tools, Integration, Fivetran, Data Analytics, Data Analysis, Data Warehousing, Big Data, Big Data Architecture, Amazon API Gateway, Data Reporting, Data, Data Warehouse Design, Code Architecture, Data Architecture, System Architecture, Requirements & Specifications, User Requirements, Front-end, Vi, Deep Learning, Data Structures, Mathematics, Computer Systems, Algorithms, Operating Systems, Programming Methodology, Networks, Compilers, Artificial Intelligence (AI), Open-source LLMs, Neural Networks, Natural Language Processing (NLP), PCI, PCI Compliance, PCI DSS, Computer Organization, Dynamics CRM 365, Web Development

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