Renne Castellanos

Senior QA Automation Engineer / Full-Stack Developer

I have been building software since 2012 and testing it since 2014, when I automated my first suite in Selenium. Web, mobile and desktop applications, the databases under them, and the teams behind them. Today I put that developer's view to work on quality, designing QA processes and automation suites in TypeScript, Playwright and Cypress, and bringing in AI agents where they take real work off the team's plate.

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Renne Castellanos

Medellín, Colombia. UTC−5
Remote, international product teams
English C2, Spanish native

About me

I started as a web developer in Caracas in 2012, and over the following years worked through every layer of a product: databases in MySQL, PostgreSQL and SQL Server, backends in C# and PHP, frontends in Angular, React and Vue, and mobile apps with Ionic. In 2014 I joined M5 Team and spent a year and a half in QA, automating tests in Selenium on top of the Acumatica ERP framework and leading the QA team's work and deliveries: my first taste of test automation, and the reason I never stopped looking at software from the tester's side. Along the way I also led a software team, planned requirements, and designed the interfaces and brands for the products I built, many of them through my own studio, 16 Ball Creations.

That background is what I bring to quality assurance. I evaluate a project across its whole life cycle, read the code when a test fails, and look for the defect where it actually lives, whether that is a process, a dataset or a line of backend code. I care about good development practices, about leading and training teams, and about building platforms that are meant to grow for a long time.

Outside work I produce PsicoFormando, a psychology project I make with my family, I play bass and sing in Neural, a metal band, and I read, mostly about personal development. There is more about that side further down.

My professional journey

From web developer to QA automation with Selenium, to software team lead, to full-stack work for product companies, and back to QA automation with modern tooling. The path company by company is right below.

See the full career history ↓

How I approach QA

Four working principles, and what each one looks like in practice.

01

Assess before you build

When I took over an existing automation project at zinc.tech, the first deliverable was not a test. It was an assessment of whether the project could be extended at all, and a technical roadmap for a version that could scale. Everything built after that followed the roadmap.

02

Process first, automation second

Automation only speeds up what a team already does well. At Tenant Evaluation I started by mapping every process of the system under test as diagrams and defining how testing is identified, planned and tracked. With that map in place I wrote more than 130 test cases in the first week, then built automation prototypes for the repetitive work.

03

Test data is part of the product

A suite is only as good as the data it runs on. I split the zinc.tech suite into a data-driven track and an end-to-end track, and built a generator that produces large datasets and bulk-loads them into the platform, so the tests run against realistic volume.

04

A developer's eye on every defect

Years of full-stack work mean I don't stop at the bug report. I trace failures across processes and data layers, and when the fix is mine to make I deliver it, so the suite keeps running reliably instead of piling up known failures.

Experience

The short version, role by role. The CV has the full detail.

08/2026 to 09/2026

Senior QA Automation Engineer, Tenant Evaluation LLC

Built and matured the QA function by combining manual testing, process improvement and automation. Documented every process of the system under test as diagrams, defined and standardized how testing is planned and tracked, validated new features and fixes, and developed the Playwright automation prototypes behind the team's test automation strategy, with Claude for test generation.

130+ test cases written in the first week, with every process of the system mapped in diagrams.

Playwright · Testmo · Claude · Jira and Confluence

04/2025 to 08/2026

Senior QA Automation Engineer, zinc.tech

Took ownership of an existing automation project, assessed its viability, and architected a complete automation ecosystem from the ground up: a data-driven track and a general end-to-end track, a control dashboard for on-demand runs and health reports, a large-scale test data engine, and AI agents configured to take on specific testing and development tasks.

700+ automated test cases covering business workflows, functional checks, APIs and third-party integration responses.

TypeScript · Vue.js · Node.js/Express · AI agents

06/2023 to 11/2025

Mid/Senior Software Developer, Gorilla Logic

Two and a half years across outsourced client projects and internal initiatives, growing from frontend work to full-stack delivery and leadership contributions.

  • Systech, 05/2025 to 09/2025. Custom solutions on the client's proprietary framework, plus automated test pipelines to keep the code reliable.
  • Leadership Program (internal), 11/2024 to 04/2025. Helped design and deliver leadership training for engineering teams, and facilitated workshops and mentoring sessions.
  • Trisept Solutions, 08/2023 to 11/2024. Angular and Tailwind components for a travel-plan purchase system, PowerReviews and TripAdvisor API integrations, .NET/VB backend modules, integration and unit tests, code reviews and sprint planning.

Angular · Tailwind CSS · .NET/VB · REST APIs · Automated testing · Mentoring

06/2023 to 02/2024

Senior Frontend Developer, CDW (via UST Global)

In parallel with other engagements: maintained legacy pages built on .NET and jQuery, built new reporting components on RESTful APIs, handled edge cases around data corruption and user sessions, and created React proof-of-concept modules for the system's modernization.

.NET · jQuery · React · REST APIs

11/2021 to 11/2022

Full-Stack Developer, CIGO Tracker

Built planning and tracking features for a global delivery-management platform in Angular, with NgRx for centralized state, and designed a notifications module for real-time component interactions. Also drew the workflow diagrams, developed database migrations, maintained the legacy backend, and wrote proofs of concept and technical documentation.

Angular · NgRx · TypeScript · Database migrations

01/2013 to present

Founder and Full-Stack Developer, 16 Ball Creations

My personal brand for freelance development, started with the goal of growing it into a development company. Over thirteen years it has shipped Vue and React applications, WordPress platforms with custom backends, an Ionic 5 app on a Yii2 backend, an education platform for TradingCore S.A.S. and brand identities, for clients in Venezuela and Colombia, planned, designed and built end to end.

Vue · React · Ionic/Angular · WordPress · Yii2 · Graphic design

See the studio's work ↓

12/2018 to 01/2020

Full-Stack Developer, Virtual Community Builders S.A.S.

Built employment, entrepreneurship and training platforms for Medellín's digital-government initiative, custom WordPress and BI platforms for enterprise clients such as NewStetic and CED Antioquia, and integrated AI assistants (Watson and Dialogflow) into Moodle learning platforms. Led database modeling, technical documentation and Git administration, and mentored junior developers.

WordPress · Moodle · Watson/Dialogflow · BI · Mentoring

07/2018 to 12/2018

Freelance Software Developer, Vennex Group S.A.S.

Optimized code and SQL scripts for the CUP CMS platform, ran data cleanup, migration and restructuring for a government client (INCIVA), guided junior developers and helped plan the team's work.

SQL · Data migration · CMS

11/2015 to 03/2018

Software Development Lead, OENS Ingeniería

Led a development team building web-based industrial control systems and ERP tools, deeply integrated with production: requirement planning, UX, database design and team management. Delivered two major versions of SCPC, a concrete production control system (2015 and 2017), SICAP for LafargeHolcim, and the first Modularity ERP, the seed of the multi-company platform I still develop today. Also consulted on Microsoft Office 365.

Team leadership · Requirement planning · UX · Database design

01/2016 to 11/2016

Full-Stack Developer, Buenacausa.org

Developed the platform on Yii Framework 1.1.

PHP · Yii 1.1

06/2014 to 01/2016

QA Automation Lead, M5 Team

My first role in QA and test automation, for a year and a half. Automated tests with Selenium on the Acumatica ERP framework, led the QA team by managing the work and organizing deliveries, and tested, and helped build, modules for Acumatica ERP such as Service Management.

Selenium · Acumatica ERP · Team lead · Functional and regression testing

01/2012 to 09/2014

Earlier roles

Web developer at Güep Group, building websites for artists and professionals across industries, and at 4Geeks, building landing pages and corporate sites. Also a short stint at MirrorHouse Games on an unreleased browser game, SummerFarm.

Skills and tools

The most current skills first, the rest one click away. Each bar starts when I started using that skill.

Right nowOpen to my next QA automation role, and building Modularity: Angular 20, Django and Playwright suites, developed with Claude Code agents.

Test automation: Selenium, Cypress, PlaywrightSelenium at M5 Team (2014–16), Cypress from 2021, Playwright today
~6y
TypeScript, Vue.js and Node.js/Expresssince 2021, Cigo Tracker (Angular), then zinc.tech
~5y
QA process design, test strategy and QA leadershipQA lead at M5 Team (2014–16), then zinc.tech and Tenant Evaluation
~2y
AI agents for testing and developmentsince 2025, zinc.tech, then Claude Code agents in Modularity
~1y
Python, Django and microservicessince 2026, Modularity
~1y
Frontend: JavaScript, Angular, React, Vuesince 2012, 4Geeks and Güep Group
~14y
Backend: PHP (Yii, Laravel), C#/.NET, Node.jssince 2012, Güep Group, then M5 Team, OENS and Gorilla Logic
~14y
Databases: MySQL, PostgreSQL, SQL Serversince 2012, design and development
~14y
Manual and functional testingsince 2014, M5 Team (Acumatica ERP)
~12y
Team leadership, mentoring and Scrumsince 2014, M5 Team, then OENS, VCB and Gorilla Logic's leadership program
~11y
Graphic design, brand identity and UIsince 2013, 16 Ball Creations
~14y

Earlier in my career, no longer my daily stack: WordPress sites and custom PHP · Ionic 5 with a Yii2 backend · Selenium on the Acumatica ERP framework (M5 Team, 2014–16).

Toolbox

Testing and QA
  • Playwright
  • Cypress
  • Selenium
  • Puppeteer
  • Testmo
AI and automation
  • Claude
  • Claude Code agents
  • Prompt engineering
Languages
  • TypeScript
  • JavaScript
  • Python
  • PHP
  • C#
  • SQL
  • C++
  • Java
Frontend
  • Angular
  • React
  • Vue.js
  • Ionic
  • Tailwind CSS
  • SASS/LESS
  • jQuery
Backend
  • Node.js/Express
  • Django
  • .NET/VB
  • Laravel
  • Yii
Data
  • PostgreSQL
  • MySQL
  • SQL Server
DevOps and tools
  • Git
  • Docker
  • Azure
  • Jira
  • Confluence
  • Trello
Design and multimedia
  • CorelDRAW
  • DaVinci Resolve
  • 3ds Max
  • SketchUp
  • Unreal Engine 4
  • Unity

What I built at zinc.tech

An existing automation project, assessed and turned into a complete automation ecosystem, from the ground up.

700+
automated test cases: business workflows, functional checks, APIs and third-party integration responses
2 tracks
a data-driven suite fed by a large-scale data engine, and a general QA suite for end-to-end validation
1 dashboard
to run the whole suite on demand, watch results live and generate system health reports
AI agents
configured with tailored docs and guidelines to take on specific testing and development tasks

What people I worked with say

Two recommendations from my managers, as they appear on LinkedIn.

Renne (Xan) has a great capacity for learning and approaches development always with a positive mindset. He's perseverant and determined. He's also someone who really cares about team spirit and making sure that the achievements of his colleagues are recognized and celebrated.

Furthermore, Renne also has a strong background in software quality. This immediately makes him a much better than average developer. His approach to development leads to fewer major bugs, with only minor observations and post-prototype phase enhancements.

Cyrille B. DelavenneSaaS Engineering Leader. Managed Renne directly, October 2022

Working with Renne has been a pleasure. His professionalism combined with his creativity and skillful execution has ensured that his deliverables are always of the highest quality.

His analytical approach when taking on new and complex projects has proven extremely useful for the team. He is dedicated and does not shy away from a challenge - A team player that I would recommend and welcome to my team in the future.

Dani SaraDirector of Product, Fintech. Managed Renne directly, October 2022
Read them on LinkedIn →

Projects

Most of my work belongs to the companies I built it for. This section is for my own: Modularity, the platform I am building on my own time, this site, and my code on GitHub. The client work from my studio has its own section below.

Personal product, evolving since 2015

Modularity dashboard for a demo café: today's sales, orders, tables, work queue, pending invoices and team status

Modularity

A multi-company ERP for small businesses that are not run by IT professionals. It started in 2015 as an ERP for a concrete producer and has grown, version by version, into a platform where one core adapts to cafés, auto repair shops, salons and clinics by switching modules on and off and mapping generic entities to each industry's own words: a table, a vehicle, a client or a patient; a waiter, a technician, a stylist or a nurse.

Nine core modules, from orders, scheduling and inventory to production queues and billing, run on fifteen Django microservices behind an nginx gateway. The Angular 20 frontend speaks English and Spanish, renders by role for six user roles, and authenticates with JWT.

It is also where I practice what I preach: Playwright end-to-end and API suites built on page objects, and a Claude Code workflow with seven specialised agents for Django, Angular, database design, Playwright testing, security audits and code review, plus a pre-commit security hook.

  • Angular 20
  • TypeScript
  • SCSS
  • Django 5
  • Django REST Framework
  • PostgreSQL
  • Redis
  • Docker
  • nginx
  • Playwright
  • Claude Code
Ask for a demo Private repository, walkthrough on request
  • 15Django microservices behind an nginx API gateway
  • 9core modules, activated per business
  • 4industries out of the box: café, auto repair, salon, clinic
  • 25Playwright spec files covering the UI and the APIs
  • 7Claude Code agents, each with its own role in the workflow

Portfolio and CV

This site

The page you are reading. Hand-written HTML, CSS and JavaScript with no framework, hosted on GitHub Pages.

  • HTML
  • CSS
  • JavaScript
  • GitHub Pages
GitHub repository

Code on GitHub, since 2013

Technical tests and experiments

Around twenty public repositories: technical assessments and small experiments across the stacks I have worked in, from a Yii2 and Vue data visualization (TalentMap) to React, Angular, Vue and Ionic apps.

  • Vue
  • React
  • Angular
  • Ionic
  • Yii2
  • PHP
Browse repositories

My studio, since 2013

16 Ball Creations

16 Ball Creations is the personal brand I use for freelance work: full-stack development, graphic design and audiovisual production. I started it in 2013 with the idea of growing it into a development company, and that is still the goal. So far it is where I have shipped the most work end to end: planning with the client, designing the interface and the brand, building frontend and backend, and putting it live.

Visit the studio's website →Instagram, @16ballcreations →

  • 2015 to today · The studio's own product

    Modularity ERP

    The standalone ERP I develop under the studio. It was born in 2015 as an ERP for a concrete producer and has grown into a multi-company platform for small businesses in any industry.

    See Modularity in Projects ↑

  • 2020 · Web and mobile platform

    Es De Todos

    A WordPress platform with a companion Ionic 5 mobile app, both served by a custom Yii2 backend.

    • WordPress
    • Ionic 5
    • Angular
    • Yii2

  • 2019 · BI platform, as a contractor

    Socialgrafo

    A BI and data-management platform in Vue.js for Corprefer S.A.S., built as a contractor during my time at Virtual Community Builders.

    • Vue.js
    • BI
    • Data management

  • 2020 to 2021 · Built during the pandemic

    Emprende Fácil Mujer, HorusInvestmenth, TradingCore

    Two React applications, Emprende Fácil Mujer and HorusInvestmenth, and an education platform for TradingCore S.A.S.

    • React
    • E-learning

  • 2020 · Site, brand and photography

    Puto King Tattoo Art

    The whole package for a tattoo studio: logo, WordPress website and the photography on it.

    • WordPress
    • Branding
    • Photography

  • 2015 · Custom development

    Los Javelin, AGEVEN, Promofactory

    Custom development for three Venezuelan companies: Los Javelin, Agendas Empresariales E.S. de Venezuela and Promofactory de Venezuela.

    • Custom development

Have a project in mind? 16 Ball Creations takes on freelance work: web and mobile apps, custom backends and brand identity.

Tell me about it

Beyond the code

The creative side

Not everything I make compiles. Video, design, photography and music are where I practice the other half of the job: looking at a problem from an angle nobody asked for. It is the same instinct that makes a good tester, asking "what if someone uses this differently?", pointed at a story, a logo or a song.

Since 2020 · Producer, editor and designer

PsicoFormando

A psychology project I make with my family, on YouTube, Instagram and TikTok, with its own website. I produce and edit the videos, design the graphics, built the website and run the digital marketing strategy. Turning expert content into something anyone can follow is the same skill I use to explain a defect to a product owner.

  • 18k+followers across platforms
  • 8.6kTikTok
  • 6.3kInstagram
  • 3.7kYouTube

psicoformando.comYouTubeInstagramTikTok

Multi-instrumentalist · Metal

Music

I play bass and drums and I sing, mostly metal. I play bass and sing backing vocals in Neural. Rehearsing the same passage until it is right is not so different from chasing down a flaky test, and a band only sounds good when everyone listens to each other.

Neural on SpotifyInstagram

Design, 3D and photography

Brand identity and editorial design

Logos for Puto King Tattoo Art, PsicoFormando and 16 Ball Creations, book covers for LS Innovaciones, Transportes La Represa and AreCar Corporación, and photography for client sites. My degree majored in computer graphics, and design never left: CorelDRAW, DaVinci Resolve, 3ds Max, SketchUp, Unreal Engine and Unity.

2006–2008 · Volunteer

Venezuelan Red Cross

Brigade volunteer in humanitarian aid for natural disasters. Staying calm and methodical when things go wrong started there, long before any production incident.

Get in touch

I am open to Senior QA Automation and full-stack roles in remote, international product teams, and to consulting on test automation, platform design and team leadership. I am especially interested in platforms built to scale and in the gaming industry.

Where to reach me

Email
xan217@gmail.com
Freelance and studio projects
16ballcreations@gmail.com
LinkedIn
linkedin.com/in/xan217
GitHub
github.com/xan217
CV
Download the PDF
Based in
Medellín, Colombia. UTC−5

Email is the most direct way to reach me, and LinkedIn works just as well if that is where you found me.

If you are hiring, the PDF has the full history and is ready to attach to an application.

Send me an email
Get in touch