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Profile

Another portrait of David LJ wearing the same and in the same pose. But appears surprisedA portrait of David LJ. Slightly smiling. Wears 80'ish glasses and a green and black plaid shirt
Hey! 👋 Nice to see you again
David LJ@davidlj95
Senior software engineer

Tech stack

Backend

  • PostgreSQL
  • Amazon RDS
  • TypeScript
  • Node.js
  • Express
  • Redis
  • Ruby
  • Ruby on Rails
  • Sidekiq
  • Python
  • ... (+ 13 more)

Frontend

  • CSS
  • HTML
  • Angular
  • TypeScript
  • PWA
  • Android
  • Node.js
  • Flutter
  • iOS
  • Python
  • ... (+ 13 more)

Infrastructure

  • Docker
  • Amazon S3
  • AWS Elastic Load Balancing
  • GitHub Actions
  • Amazon API Gateway
  • Amazon Cognito
  • Amazon EKS
  • Amazon Identity Access Management
  • AWS Secrets Manager
  • Datadog
  • ... (+ 11 more)

Professional experience

Open-sourcing & freelancing logo

Open-sourcing & freelancing

Software Engineer

Summary Highlights
Took a planned break from corporate work to focus on deepening technical knowledge in areas previously limited by time constraints during full-time roles. Explored topics such as semantic release, in-depth Angular, JavaScript/Typescript bundling optimizations and the maintenance of open source (npm) libraries. Complemented technical growth with learning on team culture and engineering management, reading several key books on leadership and collaboration.
Vesto logo

Vesto

Senior Backend Engineer

Summary Highlights Tech
Backend: web APIs and background processing. Led, engineered and assisted many product features. Proposed and implemented a strategy to improve app stability by reducing error rates. Focused on enhancing observability to enable for data-driven decision-making. Optimized internal processes to reduce customer support workload
Koa Health logo

Koa Health

Senior Software Engineer

Summary Highlights Tech
Full stack: web APIs backend, web and mobile app. Led, developed and supported several product features. Worked cross-functionally with product, design, QA, DevOps, cybersecurity, research and other products teams. Enhanced the company's design system library
Telefónica Alpha logo

Telefónica Alpha

Software Engineer

Summary
Belonged to the health moonshot unit, which later spun off into a standalone company. For more details on projects and responsibilities during this period, please refer to the Koa Health entry
BTC Assessors logo

BTC Assessors

Software Engineer

Summary Highlights Tech
Full stack: web apps and peer to peer / web API backends. Served as the lead software engineer across all company projects. Acted as blockchain/distributed ledger technologies (DLT) consultant and researcher. Served as a board member in a technical advisor role for a planned in-house cryptocurrency investment fund
SEAT logo

SEAT

Software Engineer

Summary
Coordinated integration of IBC Biomechanics software into SEAT's internal IT systems for use in their biomechanical laboratory at the CARS center, located within the Martorell headquarters
Meditrauma logo

Meditrauma

IT Manager

Summary Highlights
Managed IT systems and infrastructure across all three company branches. Responsible for systems administration and general IT consulting, ensuring smooth operation of hardware, software, and network resources
IBC Biomechanics logo

IBC Biomechanics

Software Engineer

Summary Highlights Tech
Developed a reporting application and several proof-of-concept apps for interfacing with biomechanical using Bluetooth. Also managed the IT systems of the company, supporting day-to-day operations

Education

Universitat Oberta de Catalunya logo

UOC

Master's degree - MISTIC (Cybersecurity)

Score Courses
Completed coursework with a 8.14/10 grade (3.38 over 4 GPA). Unfinished degree
Universitat Autònoma de Barcelona logo

UAB

University degree - Computer Science

Score Courses
Graduated Cum laude with an 8.86 / 10 grade (3.85 over 4 GPA)
Institut de Mollet del Vallès logo

IES Mollet

High school - Science and Technology

Score Courses
Graduated Cum laude with a 9.76 over 10 grade (3.96 over 4 GPA)

Projects

Vesto app logo

Vesto app

Senior Backend Engineer

Description Tech
Worked on backend stack. Mobile app to introduce users to the world of financial investments. Enables seamless investing in US stock market via card or Bizum payments. Targeted specifically at the Spanish market
Mindset logo

Mindset

Senior Software Engineer

Description Tech
Worked in full stack. Mobile app providing Cognitive Behavioral Therapy (CBT) exercises to help patients manage depression. Web app enabling therapists to track and improve patient outcomes
Cowstamp logo

Cowstamp

Lead Software Engineer

Description Tech
Worked in full stack. SaaS web app for creating, issuing, receiving and verifying blockchain-signed credentials with a user-centric design. Leverages an in-house Java library to canonize JSON-LD graphs

Kowbucha

Lead Software Engineer

Description Tech
Web app enabling independent verification of Blockcerts verifiable credentials based on user trust decisions. Uses a custom companion Node.js & browser Javascript library created to perform the verifications.
NodeCenter logo

NodeCenter

Software Engineer

Description Tech
Worked in full stack. App to manage blockchain / DLT node deployments via an easy to use web interface that uses a REST API exposed by a companion daemon
Bitcoin Framework logo

Bitcoin Framework

Lead Software Engineer

Description Tech
Bitcoin library to create transactions with smart contracts (scripts) using puzzle-friendly design and object-oriented programming (OOP)
IBC Report Generator logo

IBC Report Generator

Lead Software Engineer

Description Tech
Worked in full stack. Desktop app that generates biomechanics reports using data from third-party applications and devices and customizable user-defined report templates
Police Translator logo

Police Translator

Lead Software Engineer

Description Tech
Worked in full stack. Hybrid mobile application offering English-Catalan police phrases with audio pronunciation and offline support. Web-based content management system

Languages

{es}

Spanish

Native

{ca}

Catalan

Native

{en}

English

Advanced

Certified B2 CEFR level