Darion Cassel, Developer in Pittsburgh, PA, United States
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Darion Cassel

Verified Expert  in Engineering

Software Developer

Pittsburgh, PA, United States
Toptal Member Since
January 8, 2016

Darion is a research scientist pursuing a PhD in computer engineering with a focus in security. He has published papers at top security conferences and has over four years of experience developing applications in JavaScript and Python. Darion has worked for organizations like Facebook, the Center for Open Science, NASA, Rackspace, CommVault, and Bristol-Myers Squibb, and has experience managing small and large teams.


NASA Goddard Space Flight Center
Qt, Octave, MATLAB, Python
Lagestee-Mulder, Inc
CentOS, Flume, Carbon, Graphite, Ruby, Jenkins, Chef, Flask, Python, PHP




Preferred Environment

Vim Text Editor, ITerm, Jupyter, Visual Studio Code (VS Code), MacOS

The most amazing...

...project I've worked on was a hyper-local anonymous messaging platform that enables individuals in conferences to communicate hassle-free.

Work Experience

Software Engineering Intern

2016 - 2016
NASA Goddard Space Flight Center
  • Led the development of a multithreaded data processing and graphing architecture called StreamGrapher, built for capturing and monitoring spacecraft data streams.
  • Built StreamGrapher with a data flow architecture, multithreading, job queues, binary data packet processing from GMSEC and UDP, and a web-based graphical front-end.
  • Created a unit test generation tool that creates almost-complete unit tests.
  • Improved the performance with dedicated UI and background worker threads.
Technologies: Qt, Octave, MATLAB, Python


2015 - 2015
Lagestee-Mulder, Inc
  • Updated the Drupal website to show greater organization of employees.
  • Reworked the SQL database employee records to match a new schema.
  • Cleaned old database records.
  • Created new pages and views to improve the employee display.
  • Updated the navigation to improve user experience.
Technologies: CSS, HTML, MySQL, Drupal, PHP

Software Development Intern

2015 - 2015
  • Aided in the transition from webmail code to a microservices architecture.
  • Extended a Python password phone-recovery API to include a delete functionality.
  • Coded an MVC-based UI with PHP, HTML, and CSS.
  • Tested with API mocking and integration tests in a Vagrant environment.
  • Developed a new logging and monitoring solution for webmail events.
  • Coded a daemon in Python for sending Syslog events to Flume and Carbon.
  • Helped configure a Jenkins build server to build a Python package for CI/CD.
  • Wrote the Chef cookbook (in Ruby) to use JMXTrans and manage related CentOS administration.
Technologies: CentOS, Flume, Carbon, Graphite, Ruby, Jenkins, Chef, Flask, Python, PHP

Software Development Intern

2014 - 2014
  • Led the development of a cloud calendar application called liveCalendar for a Simpana Webconsole product.
  • Wrote natural, language-based event recognition.
  • Built an application that merges many calendar providers into one calendar and provides both smart event recognition and natural language parsing.
  • Helped set up and test the Meteor deployment and configured the Nginx balancing.
  • Coded the application using the Meteor JavaScript framework, Java, CSS, and HTML.
Technologies: CSS, HTML, JavaScript, NGINX, Apache Tomcat, Node.js, MongoDB, Meteor

Sorted Singly Linked List Implementation

Wrote the code for a sorted, singly linked list implemented from scratch in Python. To execute it, users must run the Python 3 interpreter in a terminal window, import the class, and initialize it with an array, e.g., "ssll = SortedSinglyLinkedList([1, 2, 3, 4, 5])." Then, users can test any of its provided functionality.
2017 - 2022

PhD in Computer Engineering

Carnegie Mellon University - Pittsburgh, PA

2014 - 2017

Bachelor's Degree in Computer Science and Mathematics

University of Virginia - Virginia


jQuery, jQuery UI, Twilio API, Node.js, Carbon, Facebook API


Atom, Xcode, Sketch, Jupyter, ITerm, Vim Text Editor, Apache Tomcat, NGINX, Chef, Jenkins, Flume, MATLAB, Homebrew


JavaScript, Java, Python, HTML, CSS, Ruby, Octave, C++, C, Swift, PHP, Python 3


Meteor, Parse, MacOS, Visual Studio Code (VS Code), Drupal, Ubuntu, CentOS, Android, iOS


Flask, Qt, Knockout (Knockout.js), Mithril.js, Bootstrap, OAuth 2, Ember.js, Django


Agile Software Development, Scrum, Reactive Programming, Functional Programming


MongoDB, PostgreSQL, MySQL


Graphite, Coding, Development, Implementation

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