Alejandro Santos, Developer in Slough, United Kingdom
Alejandro is available for hire
Hire Alejandro

Alejandro Santos

Verified Expert  in Engineering

Software Developer

Slough, United Kingdom
Toptal Member Since
July 10, 2020

Alejandro is a computer scientist and software professional with an MSc in computer science. Over the past 19 years, Alejandro's worked on several projects in a variety of industries—the private sector, scientific endeavors, and research—for a range of companies and institutes, including CERN, where he recently developed software in Java and integrated it into a database system while working Agile. Alejandro enjoys working within distributed teams and values clear communication.


Java, Android, Large-scale Projects, Kotlin
Algorithms, Distributed Systems, Microservices, Agile...
ETL, Ansible, Terraform, CI/CD Pipelines, Testing, Azure Table Storage, Azure...




Preferred Environment

Git, C++, Java, Python, Linux

The most amazing...

...project I've worked on is a social networking website for people in my home city. This was long before Facebook and Instagram existed.

Work Experience

Software Engineer

2022 - PRESENT
  • Developed features for one of the largest and most complex Android apps.
  • Deployed software features to billions of mobile Android devices.
  • Implemented software features using custom in-house frameworks and tools.
  • Interacted with multiple teams across multiple time zones.
Technologies: Java, Android, Large-scale Projects, Kotlin

Software Development Consultant

2021 - 2022
  • Implemented C++ and Python services for the data pipeline, archiving historical Level 2 market depth data.
  • Implemented Bloomberg's terminal functions for the internal market depth query.
  • Conducted PR code reviews from team members as part of the team effort.
  • Tracked and fixed bugs using Jira as a reporting tool.
  • Interacted and contributed code across different teams.
Technologies: Algorithms, Distributed Systems, Microservices, Agile, Agile Software Development, Python, Python 3, C++, Microservices Architecture, Jira, Fintech, Design Patterns, Software Design Patterns, Data Pipelines, Pipelines, CI/CD Pipelines, C, Amazon Web Services (AWS), Amazon S3 (AWS S3)

Technology Lead Developer

2020 - 2021
  • Led and managed the team development efforts while following an Agile structure.
  • Improved engineering efficiency by introducing advanced CI/CD, build automation, application monitoring, and notification solutions.
  • Designed and created new microservices with a REST API for internal usage.
  • Designed and created new ETL pipelines to consume customers' data.
  • Configured Apache Airflow instances for ETL pipeline data.
  • Designed and implemented the Azure Cloud infrastructure and Docker containers from scratch.
  • Coordinated the testing effort for unit testing and end-to-end testing.
Technologies: ETL, Ansible, Terraform, CI/CD Pipelines, Testing, Azure Table Storage, Azure, Python 3, Cloud, Data, Docker, Apache Airflow, Code Architecture, Infrastructure Architecture, Architecture, Cloud Infrastructure, Web Development, Software Architecture, Flask, Flask-RESTful, Leadership, Scrum, IT Project Management, Team Management, Project Management

Senior Software Engineer

2020 - 2020
Transportation, Logistics and Supply Chain Industry (via Toptal)
  • Updated a REST API endpoint to provision new business requirements.
  • Created unit tests using JUnit for the new REST API endpoints.
  • Tracked work using Jira and interacted with the team using GitHub and Slack.
  • Created a parser for a domain-specific language (DSL) using ANTLR4.
Technologies: Microservices, Spring, Java, Web Development


2019 - 2020
Codigo Delta
  • Created the early vision of, a platform for learning programming, data structures, and algorithms.
  • Defined the roadmap along with maintaining and prioritizing the backlog.
  • Created and implemented the basic architecture of the MVP.
  • Wrote the problem statements, testing environment, and test cases.
  • Built a Jenkins pipeline in a Docker container that runs unit tests, integration tests, and end-to-end tests, along with creating new containers and deploying new application versions.
  • Implemented the automated back-end task solver in Python.
Technologies: Distributed Systems, JSON Web Tokens (JWT), Auth, Hibernate, JPA, JEE, HATEOAS, RESTful Development, REST APIs, Apache Maven, Spring Boot, Java, TypeScript, Azure, Data, Docker, Kubernetes, Cloud, Software Architecture, CTO

Tech Lead and Researcher in Computer Science

2016 - 2019
  • Led the system design and development efforts to create a simulation tool for the evolution of a Nobel-prize data-acquisition system.
  • Defined the roadmap of the project and maintained and prioritized the backlog.
  • Implemented both a type of simulation software in C++11 and small-scale prototypes in C++ and Python to model an extensive data acquisition system.
  • Published the scientific work underlying the problem statement.
  • Gave presentations about the project both internally and at conferences.
  • Implemented data analysis and reporting metrics, using Python, Matplotlib, and NumPy.
  • Tracked and fixed bugs, using Jira as a reporting tool.
Technologies: Distributed Systems, OMNeT++, Python, C++, Data, Big Data, Cloud, Code Architecture, Data Architecture, API Architecture, Architecture, System Design, Software Architecture, Leadership, Amazon DynamoDB, C

Tech Lead

2014 - 2016
  • Built a testing environment for a complex event processing (CEP) expert/streaming system.
  • Created the cross-language access bindings (C++ to Java) for the time-series database connection (SWIG).
  • Designed and implemented an efficient algorithm to read a large amount of data from the database.
  • Defined the software technologies required to solve the problem.
  • Published a scientific paper describing the algorithms and testing strategy.
  • Tracked and fixed bugs, using Jira as a reporting tool.
  • Wrote the documentation of the project and prepared internal reference materials.
  • Maintained and prioritized the work backlog for the project.
  • Conducted user interviews and usability testing.
  • Implemented the web-based version of the project using Python for the back end.
Technologies: NoSQL, DB, Distributed Systems, Streaming, Complex Event Processing (CEP), C++, Python, Java, Data, Docker, Apache Airflow, Cloud, Big Data, Big Data Architecture, Software Architecture, C

Assistant Professor

2010 - 2013
Universidad Nacional de La Plata
  • Taught courses in Java programming and Python programming.
  • Wrote the exams for the Data Structures and Algorithms course.
  • Wrote the assignments and learning materials for the Java programming labs.
  • Organized the local university's seat of ACM/ICPC, a national programming contest.
  • Managed a team of teaching assistants for labs and tests.
Technologies: Algorithms, Data Structures, Java, Leadership, Communication

Software Engineer

2010 - 2011
  • Developed and tested an internal web Java app to keep track of job applicants.
  • Developed and tested a functionality for a Ministry of Health's project to keep track of the compliance of several health regulations.
  • Refactored legacy modules to improve the maintenance and addition of new features for the client's needs.
Technologies: Hibernate, JEE, Seam, Java

Security Analyst

2009 - 2010
  • Developed an internal app using Flask and SQLAlchemy to automate the tracking of spam sources.
  • Conducted user interviews and security-related usability testing.
  • Performed security reviews of services running on the external network.
  • Carried out penetration testing on a variety of web applications.
  • Administered services and performed DevOps duties.
  • Conducted research and contributed to the development of honeypot software products and solutions.
  • Performed a forensic analysis on infected servers and wrote reports on the findings and recommendations for future operations.
  • Implemented firewall hardening and network traffic analyses.
Technologies: Distributed Systems, Networking, Security, Python, C

Software Engineer

2009 - 2009
Mercurial | Google Summer of Code
  • Implemented the basic functionality to migrate the Python 2 codebase to Python 3.
  • Worked in a collaborative and distributed team on an open-source project.
  • Communicated the required changes for the codebase migration in the project's public mailing list.
Technologies: Mercurial, Python 3, Python 2, C

Founder | CTO

2003 - 2009
La Plata Nights
  • Created the early vision of, a social media platform about the nightlife in La Plata, Argentina.
  • Conducted user interviews and usability testing of the platform.
  • Defined the roadmap, kickstarted development, and maintained and prioritized the backlog.
  • Created and implemented the basic architecture of the MVP.
  • Refactored the application multiple times to be able to handle the growing load.
Technologies: MySQL, JavaScript, PHP, Web Development, Full-stack, Web Architecture, CTO, Leadership, IT Project Management, Project Management, Team Management

Software Engineer

2007 - 2008
  • Developed custom features based on the requirements outlined by the clients.
  • Tracked and fixed bugs, documented development tasks in an internal Wiki using Trac.
  • Performed several maintenance tasks on the internal network, administered web services and the source code version control server.
  • Wrote documentation on the usage of the custom features of the product.
Technologies: Enterprise Resource Planning (ERP), Object-relational Mapping (ORM), PostgreSQL, Java


2005 - 2006
  • Developed functionality for an application to help with the hospital administration.
  • Implemented modules to produce customized reports.
  • Conducted research and contributed to the development of distributed systems and databases.
  • Taught Pascal programming to students in a course called Introduction to Programming.
Technologies: JavaScript, MySQL, PHP, Distributed Systems

Software Engineer

2003 - 2006
Argentum Online
  • Developed and designed a secure trading system between players.
  • Built the game statistics and information collection system.
  • Wrote the sockets and networking subsystem on the server.
Technologies: 2D Games, Algorithms, Networking, Sockets, C, C++
Código Delta is a platform for learning programming, data structures, and algorithms with a focus on the Spanish-speaking people of the world. Users can solve programming tasks online and review their submissions in order to improve their coding skills.

The Despacito Programming Language
Despacito is a programming language following the Latin-American culture. It is an open-source and free software (BSD license). Despacito is Turing-complete, compiled, statically typed, and supports arrays, functions, and recursion. The Despacito compiler is implemented in Python 3 in about 1,000 lines of code, without using any external libraries (e.g., parser generators) or regular expressions. The source code is available at GitHub.

Dakara Online MMORPG
Dakara Online is a C++ 11 migration of the game server-code for Argentum Online, the first MMORPG developed by South American developers. The game was very popular in its time (2002+) and was made open source around the same time.
The Dakara Online game server in a source-to-source translated version of the game server, from VB6 to C++. The Dakara game server was hosted on AWS between 2014 and 2016.


Python, Java, C++11, C++, SQL, Python 3, C++14, C++17, C, JavaScript, Embedded C++, Embedded C, TypeScript, Haskell, Scala, PHP, Lua, Python 2, Kotlin


Object-oriented Programming (OOP), Test-driven Development (TDD), Unit Testing, Web Architecture, Agile Software Development, Functional Programming, Microservices, REST, Agile, Testing, Refactoring, API Architecture, RESTful Development, Microservices Architecture, Compiler Design, Object-relational Mapping (ORM), Data Science, ETL, Serverless Architecture, Scrum, Design Patterns, Web Design Patterns, Gang of Four (GOF) Design Patterns


Docker, Linux, Ubuntu, Amazon Web Services (AWS), Embedded Linux, Jupyter Notebook, Amazon, JEE, Azure, Kubernetes, AWS Lambda, Google Cloud Platform (GCP), Amazon EC2, Software Design Patterns, Android


JSON, Relational Databases, MySQL, PostgreSQL, Redis, DB, NoSQL, Azure Table Storage, Data Pipelines, Amazon DynamoDB, Amazon S3 (AWS S3)


Data Structures, Algorithms, Networking, APIs, Back-end Development, Back-end, Architecture, Web Development, Software Architecture, Distributed Systems, Distributed Messaging, Software Engineering, Startups, RESTful Microservices, Code Architecture, MMORPGs, 2D Games, Storage, Embedded Systems, Serverless, Big Data, Big Data Architecture, Data Architecture, Infrastructure Architecture, Full-stack, Distributed Software, Economics, Finance, Data Analysis, Statistics, Object-oriented Databases, Relational Algebra, Machine Learning, RESTful Services, Spring Cloud, Cloud, Cloud Computing, Cloud Security, Cloud Storage, Compilers, Complex Event Processing (CEP), Streaming, HATEOAS, Security, Enterprise Resource Planning (ERP), Research, Data, CI/CD Pipelines, Embedded Software, Containers, Cloud Infrastructure, System Design, CTO, Leadership, IT Project Management, Team Management, Communication, Fintech, Pipelines, Simulations, Large-scale Projects


Spring, Spring Boot, Django, Boost, JNI, Flask, Spring Microservice, OMNeT++, JPA, Hibernate, JSON Web Tokens (JWT), Seam, Selenium


Jenkins Pipeline, OpenCV, REST APIs, Flask-RESTful, Auth, React, Sockets


Git, Jenkins, ANTLR 4, CMake, Postman, Zuul, GitLab, GitLab CI/CD, Apache Maven, Mercurial, Terraform, Ansible, Apache Airflow, Jira

Industry Expertise

Accounting, Marketing, Project Management

2019 - 2020

Master’s Degree in Business Administration (MBA)

Quantic School of Business and Technology - Washington, D.C., United States

2016 - 2019

PhD (Thesis Not Submitted) in Computer Science

Ruprecht Karl University of Heidelberg - Heidelberg (Germany) and Geneva/CERN (Swizerland)

2003 - 2015

Bachelor’s Degree in Informatics (Five-year Program) in Computer Science

Universidad Nacional de La Plata - La Plata, Argentina

2003 - 2012

Diploma in Programming Analysis

Universidad Nacional de La Plata - La Plata, Argentina


Getting Started with AWS Machine Learning



AWS Fundamentals: Going Cloud-Native



Microservices with Spring Cloud


Collaboration That Works

How to Work with Toptal

Toptal matches you directly with global industry experts from our network in hours—not weeks or months.


Share your needs

Discuss your requirements and refine your scope in a call with a Toptal domain expert.

Choose your talent

Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.

Start your risk-free talent trial

Work with your chosen talent on a trial basis for up to two weeks. Pay only if you decide to hire them.

Top talent is in high demand.

Start hiring