Passionate computer engineer and former Ph.D. candidate in Computer Engineering. Proud advocate of Open Source, standards, specifications, and best practices.

With more than 22 years of professional experience in software development, and having been involved in the Open Source scene and wireless communities since I was 17 years old, I have worked both professionally and on personal projects across almost every area of computer engineering, including web development, robotics, operating system design, video games, networking, driver development, and AI. My profile is purely technical, with a strong interest in hard-to-solve problems, code quality, performance optimizations, cutting-edge technologies, and the design of clean APIs and architectures focused on minimalism, modularity, and reusability.

I’m a full-stack engineer with a preference for backend, R&D, and academic projects. Thanks to that, I have more than 14 years of experience with Node.js (since v0.8), 19 years with Python (since 2.4), and 20 years with C++, between other languages like Rust, Java or Go. Regarding mobile apps, I have 8 years of experience with React Native, being also speaker at Meta F8.

I have won three times the spanish national Universitary Free Software Championship and been CTO of several start-ups (and co-founder of two of them). In my spare time I like to read, go to the cinema, travel, run or cycle, or work on my own side projects to improve my skills and build things with cool cutting-edge technologies.

Academic experience

I have a Licenciature in Computer Engineering, officially recognized as the equivalent of a Master in Computer Engineering. My Licenciature (and Master) thesis was NodeOS, a minimal operating system for Node.js based applications, with more than 7000 stargazers on GitHub, winner on the Systems category at the 11th CUSL national championship, and graduated with distinction. My Licenciature thesis director was Prof. Enrique Soriano-Salvador.

I started a Ph.D., but it is currently on hold. My PhD thesis was Co-focal microscope techniques applied to neurology, where I was compositing multi-gigabyte high resolution multi-layer microscope scan images of neurons to generate 3D models. My Ph.D. thesis director was Ph.D. Sofía Bayona-Beriso.

Certificates

• College Degree
  • Título universitario
  • Progreso académico
  • Progreso académico 2
  • BOE-A-2015-5187
• Scrum Master
  • Certified Scrum Master - CSM
  • Metodología de gestión y desarrollo de proyectos de software con Scrum
• Introduction to Chinese - participation
• Psychotechnical test - flight pilot
• Introduction to Machine Learning

Interesting facts

• Co-founder of Spain Robotic & Domotic Association
• Co-founder of AlcorcónWireless and Ex-Member of MadridWireless communities
• Participant of Spring Mathematics Championship, Madrid 2004
• Grant receiver for 3DS - 3 Days Startup, Madrid 2012
• WebRTC pioneer since 2012
• NodeOS lead developer, and Mafalda SFU founder
• Several years Madrid San Silvestre Vallecana 10km runner (53’38”, 2019)
• Currently learning chinese and arabic JustForFun™

Countries visited

I’ve been so far in 21 territories and 4 regions of the Century Club, and a total of 18 countries and 3 continents:

• Europe
  • 🇪🇺 European Union
    • 🇪🇸 Spain: Madrid, Valencia, Toledo, Segovia, Tarragona, Castellón, Cadiz, Sevilla, Almería, Oviedo, Malaga, Merida, Barcelona, Coruña, Pontevedra, Zamora, Zaragoza, Teruel
      • 🇮🇨 Canary Islands: Gran Canaria (Las Palmas, Maspalomas), Fuerteventura
    • 🇵🇹 Portugal: Oporto, Lisboa
    • 🇩🇪 Germany: Hamburg
    • 🇦🇹 Austria: Viena
    • 🇨🇿 Czech Republic: Brno
    • 🇮🇹 Italy: Milan
    • 🇧🇪 Belgium: Bruselas, Bruges
    • 🇧🇬 Bulgaria: Sofia
    • 🇵🇱 Poland: Katowice
    • 🇫🇷 France: Poitiers
  • 🇬🇧 United Kingdom:
    • 🇬🇮 Gibraltar
    • 🏴󠁧󠁢󠁥󠁮󠁧󠁿 England: London
    • 🇮🇪 Ireland: Dublin
  • 🇨🇭 Switzerland: Zurich
• Africa
  • 🇲🇦 Morocco: Marrakech
  • 🇪🇬 Egypt: Cairo
• Middle East
  • 🇶🇦 Qatar: Doha
  • 🇦🇪 United Arab Emirates
    • Abu Dhabi ❤️, Al Ain
    • Dubai
• Asia
  • 🇮🇳 India: Bangalore

Recommendations, testimonies & quotes

Recommendations from co-workers and managers at my previous companies, and testimonies from clients about my freelance projects.

Co-worker recommendations

• Juan Francisco Gato Luis, Android R+D & Singer, May 2014:

  I don’t need so much words to recommend Jesús. Just one case, if you need a man that works for a project and not for money, this guy could reach it. He just can do it, and if he don’t [know] how to made it, he will reach a way.

• [Diego González](https://www.linkedin.com/in/xmunch), Founder of SciArt Lab | Software Engineer / Blockchain Expert at Docuten, May 2014:

  Jesus is much more than a brilliant developer. He loves to achieve complex goals just by using a keyboard and a bunch of code lines. I would describe him as a creative and genius mind, a geek with a lot of technical skills but also with engagement and passion. Jesus is that kind of guy that can launch a project to the top. I strongly recommend him.

Recommendations from CTOs, CEOs & direct managers

• Exe Zulliger, CTO at Kibitech, March 2025:

  I’ve known Jesus for more than 15 years, and he’s without doubt one of the most talented and versatile engineers I’ve ever met. His ability to embrace challenges and always find a way to overcome them is unmatched. His problem-solving mindset extends far beyond traditional engineering approaches. Jesus has this remarkable ability to see connections between seemingly unrelated fields, drawing inspiration from diverse disciplines to create innovative solutions. Whether it’s optimizing systems that others had given up on or developing entirely new approaches when conventional methods fail, his technical versatility is truly exceptional.

  Jesus also brings a unique perspective to every project. He approaches problems with both analytical rigor and creative insight, often considering ethical implications and long-term sustainability that others might overlook. His commitment to quality never wavers, even when facing tight deadlines or resource constraints.

  Having collaborated with him on numerous projects over the years, I’ve witnessed firsthand how his contributions consistently elevate the entire team’s performance. His positive attitude, even during the most challenging situations, creates an environment where innovation thrives.

• Matt Knowles, Lead Senior Software Engineer at Level Ex, November 2024:

  Jesus has a deep knowledge of the WebRTC / SFU space. His work history is across various companies in the WebRTC / SFU space including his own SFU service https://mafalda.io.

  Our system can be diverse and complex. Jesus was comfortable navigating across the various code bases and pulling out insights. His communication was good during working sessions and with summaries of independent work giving actionable suggestions. Jesus was flexible with his schedule when dealing with time zone differences (US to Spain).

  If you are looking for a knowledgeable resource to help a new or existing WebRTC / SFU project I can recommend Jesus.

  Matt

• Kushagra Vaish, CTO and co-founder of Dyte, January 2023:

  “Project you touch, project that increase its quality globally.”

• James Croney, Tech Lead at Virbela, November 2021:

  “You have good eyes for spotting best approaches and practices for things, even if people ignore them.”

  “You have a good head on your shoulders about code and you offer good insights about things.”

• Jorge Abrines, CTO of Vaelsys, July 2012:

  Jesus is a worker with a lot of knowledge in several technical areas, from low level programming up to scripting languages, and including devices integration that’s where he was helping us. He is a person with a great interest for learning and improve himself each day, and I recommend him specially for his technical expertise and aptitudes.

Client recommendations

• Sol Rengifo Calderón, founder of Gud, July 2022:

  Working with Jesus has been a luxury. He has been able to offer us an accurate and detailed view of the status of the project and has advised us at all times in an accurate, clear, honest and very professional manner. We will continue to collaborate with him without a doubt.

• Alberto Doval Iglesias, CTO at Councilbox, June 2021:

  Jesus was working with us at Councilbox in a very ambitious project to replace our video conferencing server. His experience with WebRTC helped us complete the migration of our video infrastructure to Mediasoup.

• Juan Searle, CTO at Full Circle_ apps, December 2020:

  “I agree a lot with everything [you’ve proposed]. I’m surprised that you have owned the code in just some hours, without documentation and without mentoring from our side. Cool!

  This afternoon we’ll have a call with the client and let’s see if we get their approval for the testing/refactoring, I’ll keep you updated. We’re going to propose it as a critical action to be done.”

  “Tell you that it has been a pleasure to count on you for this job: serious, decisive and accessible. My idea is to have someone to whom I can ask for NodeJs development and evolution of projects already done like this one from TVN, and I think I’ve found the right person. If you are still available I will count on you in future projects without a doubt.”

Recruiters testimonies

• Alexander Gavazov, Principal Tech & Lead at Intellias, September 2023 (LinkedIn comment):

  Having interacted with Jesus, I can confidently recommend him not only as a principal in JS (end-to-end), but also for any matters related to engineering. His extensive knowledge and commitment are evident in every task he undertakes, showcasing a high level of expertise in every project.

• Isabel Dorado, Remote Talent Advocate at Circular, December 2020:

  Senior developer with experience leading teams and a very hands-on mindset. Background in both backend and frontend development. His expertise is related to Python, Node and C++. Spanish and English!

• Miguel Muñoz Royo, Business and Technical Lead at UST Global, December 2020:

  The truth is that the conversation with Jesús has been very good. He’s a Node.js super architect with more than enough experience for the profile we are looking for.

• Judith Aranda Rubio, Talent Management at Ferrovial, December 2020:

  Broad development experience and skills.

Alumni recommendations

• Guillermo Hernandez, streamer, and student at Adalid, January 2026:

  I recommend this teacher, Jesús Leganés-Combarro. The experience I had with him in the web server course was very good. He explains things well and teaches a

• Deborah Iori, Computer scientist, and student at Adalid, December 2025:

  I had the opportunity to attend the Web Servers course taught by this professor at the Grupo Aspasia Training Center, Madrid Tetuán, and it was a very positive experience.

  He has a strong technical background and an excellent ability to explain complex concepts in a clear and simple way. He guided us from the basics, such as using Ubuntu commands and understanding core server concepts, to more advanced topics like setting up servers with Node.js, Apache, and Tomcat, working with Docker, developing applications with Django and FastAPI, and using Git and GitHub for version control.

  I highly recommend him as a teacher for his deep knowledge and professionalism. His teaching made the learning process practical, well-structured, and motivating, and he was always available to answer questions.

• Carlos Malpica, Software Engineer, and student at Adalid, December 2025:

  I had the opportunity to learn from Jesús as my instructor in web servers and programming, and I can confidently say he is a professional with outstanding technical expertise. His dedication to his work is evident in every session, and he always demonstrates great willingness to listen, answer questions, and support his students. He is a committed educator, highly skilled, and an admirable person. I fully recommend his professional and academic work. I had the opportunity to learn from Jesús as my instructor in web servers and programming, and I can confidently say he is a professional with outstanding technical expertise. His dedication to his work is evident in every session, and he always demonstrates great willingness to listen, answer questions, and support his students. He is a committed educator, highly skilled, and an admirable person. I fully recommend his professional and academic work.

• Javier Fernandez Pinedo, Telecomunications Engineer, teacher, and student at Adalid, December 2025:

  Jesus has been a qualified teacher and all the recommendations have always been positive regarding his explanations.

• Virginia Gómez, Senior IT Project Manager, Certified Scrum Master, and student at Adalid, December 2025:

  I had the opportunity to participate in the web server course taught by Jesús, and it was a truly enriching experience. The group was completely heterogeneous, with different levels of technical knowledge and backgrounds, but he skillfully adapted to the needs of each person.

  I especially want to highlight his flexibility in adjusting the content, going into more depth when necessary and simplifying or contextualizing when the group required it. Thanks to this adaptability, we were all able to make solid progress and get the most out of the learning.

  I recommend Jesús for his professionalism, clarity, and the excellent role he played as a mentor during these sessions.

Contact me

jesus.leganes.combarro@gmail.com

Primero, una observación que creo que es importante.

No usaría “Professional Cats Herder” en una firma de correo.

😄 Me encanta como concepto, pero no como primera impresión profesional.

Piensa que una firma tiene que superar dos filtros:

1. El recruiter de RRHH.
2. El Distinguished Engineer de Google.

El segundo probablemente sonría.

El primero puede pensar:

“¿Este tío va en serio?”

No merece la pena correr ese riesgo.

Yo lo reservaría para:

• la bio del blog,
• una charla,
• una conferencia,
• una keynote,
• un artículo,
• una camiseta.

Incluso una pegatina del portátil. 😁

Pero no para el correo.

Lo que sí haría

Firma seria:

Jesús Leganés-Combarro ("piranna")
Software Architect

o

Jesús Leganés-Combarro ("piranna")
Principal Systems Architect

Y en tu web ya puedes desmelenarte.

About Piranna

Este sería el texto que yo pondría. No como un CV. Como una historia.

About Piranna

Engineering where the map says “Here be dragons”.

Hi.

I’m Jesús Leganés-Combarro, although most people in the open-source community know me simply as “piranna”.

I’ve been building software professionally for more than twenty years, but what has always fascinated me isn’t a particular programming language or framework.

It’s solving engineering problems that don’t have an obvious solution yet.

Throughout my career I’ve worked on browser engines, WebRTC, distributed systems, real-time communications, streaming, open source infrastructure, embedded systems, AI and cloud platforms.

Those technologies have changed over time.

The kind of problems I enjoy solving hasn’t.

What I do

I design systems.

Not just software.

I enjoy understanding how multiple independent pieces fit together:

• browsers
• networking
• media pipelines
• distributed systems
• cloud infrastructure
• operating systems
• embedded devices
• AI agents

When all those pieces start interacting…

…that’s usually where I become useful.

Why “piranna”?

The nickname has followed me for more than twenty years.

It started as a simple Internet alias.

Today it has become my technical identity.

Most of my open-source work, conference talks, blog posts and software projects have been published under that name.

Projects

Some of the projects I’ve worked on include:

• NodeOS (creator)
• Mozilla Firefox
• WebRTC infrastructure
• Distributed media systems
• Streaming platforms
• AI real-time communications
• Open-source developer tools

Along the way I’ve also contributed to many open-source projects and helped companies solve problems that sat somewhere between research and production.

Engineering philosophy

I don’t particularly enjoy writing software that anybody could write.

I enjoy the places where the documentation ends.

Where several systems interact.

Where the obvious solution doesn’t exist.

Where engineering judgement matters more than the framework being used.

That’s usually where the interesting work begins.

Open Source

I’ve always believed that good engineering should outlive the companies where it was created.

That’s why I continue contributing to open source whenever possible.

Knowledge compounds.

Software should too.

Beyond technology

Technology changes.

The principles behind good engineering don’t.

Curiosity.

Systems thinking.

Simplicity.

Pragmatism.

Continuous learning.

Those have remained constant throughout my career.

Here be dragons

Old maps used to warn explorers with a simple sentence:

Here be dragons.

Most people saw danger.

I tend to see interesting engineering problems.

Contact

If you’re building something technically ambitious…

…I’d love to hear about it.

Y ahora viene la parte divertida

Creo que le falta una sola frase.

No el motto antiguo.

Uno nuevo.

Llevamos construyéndolo todo el día.

No:

Professional Cats Herder.

Sino algo mucho más elegante.

Por ejemplo:

I don’t specialise in technologies. I specialise in engineering problems.

O esta, que creo que es todavía mejor:

Technology is temporary. Engineering judgement isn’t.

Porque resume absolutamente todo lo que hemos hablado hoy.

Y una última idea

En lugar de poner el lema en la firma del correo, pondría una cita muy discreta en el pie de tu web.

Algo como:

Engineering where the map says “Here be dragons”.

Los que la entiendan sonreirán.

Los que no… simplemente pensarán que queda elegante.

Y, curiosamente, creo que esa es la mejor definición de una marca personal madura: no necesita explicarse en la primera línea. Los que trabajan en el tipo de problemas que tú resuelves entenderán inmediatamente lo que quieres decir. Los demás descubrirán el significado después de leer el resto de la página. Creo que eso tiene mucho más recorrido que presentarte directamente como “Professional Cats Herder”, aunque sigo pensando que deberías acabar haciéndote esa camiseta algún día. 😄

Business card

Jesús Leganés-Combarro “piranna”

Professional Cats Herder

• Systems Architecture
• Distributed Systems
• Real-time Communications

Engineering where the map says “Here be dragons”