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Marc Güell Segarra

Freelance full-stack developer with over 20 years of experience, including React and React Native. Today I build software with AI coding agents.

Valls, Catalonia, CET

Marc Güell Segarra

Who is behind Ondori.dev?

I'm Marc Güell Segarra, a freelance full-stack developer in Valls, Catalonia. I've worked in IT for over 20 years: since 2005, and independently under Ondori.dev since 2017. I used to write code by hand. Now I build everything with AI coding agents. I've done remote work for agencies. I've also worked with large companies and helped small startups. I love mountains, coffee and technology.

Where have I worked?

I have held 13 roles for agencies, startups and large companies.

Lya2 Sistemas de Información S.L.

Contract
Remote
Nov 2024 - Present

React Native Developer

Barcelona, Spain
Since November 2024, I develop and maintain cross-platform mobile apps with React Native at Lya2. I focus on solutions that improve healthcare management for medical professionals.

GISCE-TI, S.L.

Contract
Remote
Nov 2020 - Present

Senior Frontend Developer

Girona, Spain
Since November 2020, I create and maintain a modular, dynamic server-driven UI front-end system for the main ERP solution of GISCE-TI.

Editorial Claret

Contract
Remote
Apr 2018 - Present

Full Stack Developer

Barcelona, Spain
Since April 2018, I develop a React Native app and its serverless infrastructure on AWS at Editorial Claret. I have also created a few of the company's static websites.

Ondori.dev

Self-employed
Mar 2017 - Present

Freelance Full-Stack Developer

Valls, Catalonia
Since March 2017, I work as a freelance full-stack developer under Ondori.dev.

We Agile You, S.L

Contract
Remote
Nov 2024 - Feb 2025

Frontend Developer

Barcelona, Spain
From November 2024 to February 2025, I was a frontend developer at We Agile You. I worked with React and TypeScript on planningpokeronline.com and other company projects, including JIRA plugins and apps.

Scopely

Contract
Remote
Jul 2022 - Nov 2024

Frontend Developer

Los Angeles, California, United States
From July 2022 to November 2024, I was responsible for the front-end of playscrabble.com and its HTML5 game engine at Scopely.

niikiis

Contract
Remote
Oct 2020 - Feb 2021

Full Stack Developer

Barcelona, Spain
From October 2020 to February 2021, I worked at niikiis as a React developer and built backend microservices on the AWS stack.

Human Life Technologies, LLC

Contract
Remote
Sep 2020 - Feb 2021

React Native Developer

Massachusetts, United States
From September 2020 to February 2021, I created an iOS extension for React Native that gives the company's mobile app Caller ID features linked to their CRM.

Opentrends

Contract
Remote
Mar 2017 - Apr 2018

Android Architect and Team Lead

Barcelona, Spain
From March 2017 to April 2018, I led the Android architecture and development team at Opentrends.

NEXIONA

Remote
Jan 2017 - Mar 2017

Front-end Engineer

Barcelona, Spain
From January to March 2017, I was a front-end engineer of MIIMETIQ at NEXIONA. MIIMETIQ is an IoT/M2M framework designed to simplify the creation of bespoke IoT verticals.

Moddity

Remote
Oct 2014 - Feb 2017

Full Stack Developer

Lleida, Spain
From October 2014 to February 2017, I was a full-stack developer at Moddity, part of the VIKO group. I worked on transactional mobile apps and various e-commerce services.

Tecnocom

Jun 2012 - Nov 2014

Cross-platform Senior Mobility Developer

Tarragona, Spain
From June 2012 to November 2014, I developed mobile applications for a leading Catalan financial institution at Tecnocom.

Getronics

Jun 2007 - Jun 2012

IBM Mainframe z/OS Analyst Programmer

Tarragona, Spain
From June 2007 to June 2012, I analyzed and developed applications with PL/I and DB2 in a banking HOST environment at Getronics. My tasks included resolving incidents, customer communication, project estimation, documentation and team supervision.

What technologies do I use?

I have worked with 51 technologies. Many of them appear in the 31 projects below.

  • AI Coding Agents
  • Claude Code
  • Codex
  • OpenCode
  • JavaScript
  • TypeScript
  • React
  • React Native
  • Next.js
  • Node.js
  • AWS
  • Vite
  • GitHub Actions
  • SEO
  • Styled Components
  • Tailwind CSS
  • Mobile Game Development
  • Supabase
  • Cloudflare
  • Lambda
  • DynamoDB
  • Cloudformation
  • Amplify
  • API Gateway
  • iOS
  • Objective-C
  • Android
  • Java
  • CSS
  • Web
  • S3
  • Cognito
  • MongoDB
  • Angular.JS
  • Express
  • Bootstrap
  • Cloudfront
  • Route53
  • Unity
  • Maven
  • Github Pages
  • Clean architecture
  • Jenkins
  • Sonarqube
  • Dexguard
  • Cordova
  • Ionic
  • Swift
  • Three.js
  • Raycast
  • Developer Tools

What have I built?

31 projects, from 2013 to 2026.

Mulassa Tap Tap Dance

Mulassa Tap Tap Dance (2026) is a free rhythm game in Catalan. You dance the Mulassa de Valls to the beat, tap GUA and PA, beat the challenge and share your dance.

Three.js
Vite
Supabase
Cloudflare
Mobile Game Development

Campanar de Valls LEGO

Campanar de Valls LEGO (2026) is an interactive 3D model of the bell tower and church of Sant Joan de Valls, built with LEGO bricks. It has an assembly animation and export options.

TypeScript
Three.js
LDraw
3D
Open Source

Menu Bar Icon Search

Menu Bar Icon Search (2026) is a Raycast extension that finds and opens macOS menu bar icons, including the hidden ones.

Raycast
Swift
macOS
Productivity Tools

CPU Load Bar

CPU Load Bar (2026) is a macOS menu bar app that always shows the CPU load and the memory pressure.

Swift
macOS
Menu Bar
System Monitoring

Yami – Bookmark Launcher

Yami (2025) is a Chrome extension that opens your bookmarks with a keyboard shortcut. It has no tracking and is open source under the MIT license.

Chrome Extensions
JavaScript
HTML
CSS
Open Source
Keyboard Shortcuts
Productivity Tools

Activity Tracker for Mac

Activity Tracker for Mac (2024) is a system tray app, built with Go, that tracks your computer activity. I made it as an alternative to macOS Screen Time.

Go
macOS
System Tray
Launch Agents
Activity Monitoring
Open Source
Productivity Tools

Highlight on Copy

Highlight on Copy (2024) is a Visual Studio Code extension that briefly highlights the text you copy, so every copy gives visual feedback.

Visual Studio Code
Extension Development
JavaScript
Text Editing
Developer Tools

Playscrabble.com

Playscrabble.com (2023) is an online Scrabble platform. I built reusable React components and libraries, drag-and-drop tile placement and sound effects, and optimized it for search engines. I used Vite for development and Next.js.

React
Vite
Next.js
GitHub Actions
SEO
TypeScript
Styled Components
Tailwind CSS

Kotobayama

Kotobayama (2020) is an open-source word game built with React Native. You guess words while climbing a mountain.

React Native
JavaScript
Mobile Game Development
Word Game
GitHub

Niikiis

Niikiis (2020) is HR management software for small businesses and companies. I worked on the full stack.

AWS
Lambda
DynamoDB
Cloudformation
Amplify
API Gateway
Javascript
React

BetterLivingPRO

BetterLivingPRO (2020) is the CRM app of a US real estate agency. I developed a React Native module for Android and iOS that adds caller ID features.

iOS
Objective-C
Android
Java
React Native
Javascript

Ringotap

Ringotap (2019) is a minimal pixel art game made with Unity. You tap red apples as fast as you can before they explode, which trains your reflexes.

Unity
Game
Older projects (19)
  • 2018 Missa de Cada Dia - App

    Missa de Cada Dia (2018) is a React Native app for Android and iOS. It is a reader for the daily mass, based on geolocation and language, with a subscription model. It ranked #1 in its category in Spain.

  • 2018 Missa de Cada Dia - Web

    This is the 2018 website of the Missa de Cada Dia mobile app. It has a mass web reader, help and contact pages.

  • 2017 Lawliet

    Lawliet (2017) is a Node.js tool that finds broken links in your documentation files.

  • 2017 Myopic

    Myopic (2017) is an Android library that replaces the app switcher thumbnail with a blur or a custom image overlay.

  • 2017 Caixabank

    Worked as a solution analyst for CaixaBank's mobility architecture SDK for Android platform. The SDK is used in the top #1 banking app in Spanish markets. Security auditor (APK reverse engineering).

  • 2016 Personal blog

    My own personal blog where I share my thoughts from time to time.

  • 2015 Pudahuel

    Santiago de Chile's airport app. Check flight information and subscribe for notifications. QR reader and parking information.

  • 2015 MySEAT

    MySEAT connected Car project. Using car data for different driving metrics, graphics, tips, and more

  • 2015 Abaxis VueScan

    An app-based solution to veterinary diagnostics, operating right from your iOS mobile device. Abaxis is an American medical technology company from Mountain View, California.

  • 2015 Animalear

    eCommerce app with veterinary products. Tinder like application for your pets with geolocation and push notifications. Integrated chat. Admin site

  • 2015 GProvincia

    Touristic app where you can consult a large number of places of interest in the Tarragona province, as well as daily offers in shops, services, bars, restaurants…

  • 2015 Pans & Company

    Mobile app for customer loyalty through offers and discounts for the restaurant chain

  • 2014 CocaCola

    CocaCola's promocodes landing page.

  • 2014 Imprify

    Application for creating photo albums, prints and photo collages. Simply, easy to use and with a lovely result.

  • 2014 Loodi

    Mobile app for scheduling and making appointments for padel matches

  • 2014 Marketing4eCommerce

    RSS-like reader app for the company news feed

  • 2014 ABA English

    English learning course app. Featured by Apple in 2014. Google Play best of 2016: 'Best self help app'. Top #5 Apple AppStore.

  • 2014 Butifarra

    Traditional catalan card game named botifarra. First multiplayer game of its kind in the AppStore, for iPhone and iPad. Reached top #1 in Cards category. In-app purchases and ads.

  • 2013 DiceRoll

    An easy implementation of a Telegram bot for rolling the dice made with Node.js.

How can I help with your project?

I help projects get built with AI. I spent about 18 years building software without it. Now I use that experience to work faster and with more confidence in the result.

I build web apps, mobile apps and backend services with coding agents. If you have a project in mind, email me with what you need and when you need it.

I work remotely, and I am available from UTC to UTC+8.