Sébastien Ballesteros

Email
sebastien.ballesteros@gmail.com
Phone
+1 646 510 5676
Location
Menlo Park, CA, USA

About me

I am an experienced Web Software Engineer with solid expertise in delivering well-architected solutions (from API design to complex React applications). I particulary love to work close to the creative process and in collaboration with product, research and design teams.

Nothing is built on stone; all is built on sand, but we must build as if the sand were stone.

—Jorge Luis Borges

Experience

Senior Software Engineer (frontend), DuckDuckGo, remote (Menlo Park)

since 2020
  • Led various fast-paced projects (using build/measure/learn cycles and working closely with product and design teams) that successfully improved the adoption and retention of DuckDuckGo's products (as measured by online controlled experiments and A/B testing).
  • Identified key areas of improvement through the development of internal tools and applications to evaluate the performance of DuckDuckGo's local search.
  • Voluntarily worked with the release team to ensure safe deployments and good testing practices.
  • Paid off some technical debt and drove the adoption of a design system and new technologies (React, Next.js, Statecharts).
  • Gained ownership and contributed to multiple areas of the code base (e.g., online controlled experiments framework, search engine result page, local search, browser extensions).

Technologies:

  • JavaScript
  • React
  • Next.js
  • Storybook
  • Node.js
  • D3.js
  • Browser extensions
  • Webpack
  • Grunt
  • ClickHouse
  • Grafana
  • Elasticsearch
  • SQL
  • Jenkins
  • HTML
  • CSS
  • RDFa
  • JSON-LD
  • Schema.org
  • Bash
  • Perl

Senior Software Engineer (full-stack), Code for Science & Society, remote (Los Angeles)

20192020
  • Led the development and release of the frontend (React) and backend (Node.js / NoSQL Database) of a new product collecting reviews on preprints relevant to the Outbreak Science community, in close collaboration with product managers and design.
  • Identified an opportunity to develop a browser extension for the product to better serve user needs at minimal cost and complexity (large code-reuse); and led its successful development and release.

Work samples: rapid-prereview (GitHub)

Technologies:

  • JavaScript
  • React
  • Choo
  • Node.js
  • Browser extensions
  • Webpack
  • CouchDB
  • PostgreSQL
  • Redis
  • Redisearch
  • CircleCI
  • HTML
  • CSS
  • RDFa
  • JSON-LD
  • Schema.org
  • Bash

Technical Founder, sci.pe, Los Angeles - New York City

20142019
  • Earned acceptance to and completed Techstars NYC, Mozilla webFWD and Tigerlabs (Princeton) programs (the company was also known as Standard Analytics and science.ai).
  • Helped major scholarly publishers to successfully transition from an XML/print-first workflow to an HTML/web-first one.
  • Architected and built a complex React/Redux application (collaborative task completion, roles management, real-time updates, offline support, rich text editing, annotations, payments, first-class support for print).
  • Designed and built a hypermedia API (and associated data model) based on schema.org actions.
  • Architected and built a document transformation service (OOXML to HTML, image resizing, video transcoding).
  • Built a CI/CD pipeline and deployed and monitored the application on AWS.

Work samples: science periodicals GitHub organization, Twitter threads (1, 2)

Technologies:

  • JavaScript
  • React
  • Redux
  • D3.js
  • Node.js
  • Webpack
  • Browserify
  • Zeromq
  • CouchDB
  • MongoDB
  • PouchDB
  • Redis
  • Lucene / ElasticSearch
  • AWS
  • Docker
  • CircleCI
  • Stripe
  • HTML
  • CSS
  • RDFa
  • JSON-LD
  • Schema.org
  • Bash
  • OOXML
  • XML
  • Python

Postdoctoral Fellow, Department of Ecology & Evolutionary Biology, Princeton University, Princeton, NJ

20112014

Developed the infrastucture necessary to build a public library of mathematical and computational models of the dynamic processes of infectious disease spread and control, usable on demand from a web browser. The methods were successully adopted and applied by Doctors Without Borders and the London School of Hygiene & Tropical Medicine.

Work samples: GitHub repository, article on Spatial Transmission of 2009 Pandemic Influenza in the US

Technologies:

  • C
  • R
  • Zeromq
  • Python
  • AWS
  • JavaScript
  • Node.js
  • MongoDB
  • D3.js
  • Backbone.js
  • jQuery

Postdoctoral Fellow, EPIWORK project, CMAF Centro de Matemática e Aplicações Fundamentais, Lisbon, Portugal

20102011

Developed statistical and computational methods needed to achieve inference, prediction and predictability of disease spreading in complex techno-social systems.

Work samples: article on The role of weather on the relation between influenza and influenza-like illness

Technologies:

  • C
  • Zeromq
  • Python
  • R
  • Django
  • MySQL

Education

Ph.D. thesis in Ecology and Evolution, Laboratory Ecology and Evolution (UMR 7625); Universite Pierre et Marie Curie, Ecole Normale Supérieure, Paris, France - Awarded with distinction and special mention from the examination board

20062009

My thesis focused on the development of statistical and computational methods to understand the processes driving outbreak dynamics of infectious diseases. Developements focused on influenza, dengue and HIV.

Technologies:

  • Blackboard, pen & paper
  • C
  • R
  • Python

Master’s Degree by research, Universities Paris 6 and Paris 11, AgroParisTech, Ecole Normale Supérieure, with honors (ranked first)

2005–2006

Ecology, Biodiversity and Evolution, speciality Theoretical Ecology and Modeling.

Engineering school (“Grandes Ecoles”), INA P-G (now AgroParisTech), Paris, France

20032005

France’s top post graduate engineering school for agronomy and life sciences (part of the ParisTech Grandes Ecoles).

Higher School Preparatory Classes (classes préparatoires aux grandes écoles), Lycée Jean-Baptiste-Say, Paris, France

20002003

Intensive preparatory course with the main goal of training students for enrollment in one of the Grandes Ecoles.

Baccalauréat général série Scientifique (S) - Awarded with distinction, Paris, France

2000

The S stream of the Baccalauréat prepares students for work in scientific fields.

Teaching

  • Statistics (undergraduate students) at the Muséum National d’Histoire Naturelle and Princeton University.
  • Scientific animation (popularisation works) in the Muséum National d’Histoire Naturelle. Those activities were based on interactive computer simulations that I developed for the Muséum.

Technological skills

Programming
JavaScript
TypeScript
C
Python
R
Bash
Web development
React
Redux
Node.js
Next.js
XState
D3.js
Webpack
Browserify
HTML
CSS
RDFa
JSON-LD
RDF
RDF Schema
XML
SPARQL
OWL
GraphQL
Schema.org
Payments
Stripe
E-commerce
Shopify
Databases
CouchDB
PouchDB
MongoDB (certificate from 10gen)
Fauna
Firebase (Firestore)
PostgreSQL
Redis (certificate from redislab)
LevelDB
MySQL
Lucene / ElasticSearch
Cloud services
AWS
GCP
Azure
Vercel
Continuous integration
CircleCI
Operating systems
GNU/Linux
OSX
Docker
Statistics
R
SAS
WinBugs

Languages:

English
French
Spanish