Freelance Senior Mobile Software Engineer

Quality, attention to detail, commitment, best practices – is that what you’re looking for? If you are aligned with those values, then I can help you with:

  • Creating your mobile app from scratch
  • Joining your mobile team
  • Taking over, auditing, and improving your existing app

My strengths

  • +20 years of experience as a software engineer and architect
  • +10 years of experience creating mobile apps
  • Worked with companies of all sizes: startups, SMEs, and large corporations
  • Business oriented. I’m an entrepreneur myself.
  • Industry best practices (Test-Driven Development (TDD), Clean Architecture, Clean Code, SOLID principles, and CI/CD)
  • Latest Android technologies (Kotlin, coroutines, MVVM, Jetpack Compose, JUnit, MockK)
  • Experience with Flutter, Kotlin Multiplatform and many backend technologies.
  • Willing to push the boundaries and assuming new challenges
  • Passionate about my work and constantly learning


Elecnor Deimos. Worked with several native Android projects using latest technologies

Fresco. Joined the Android team for 9 months. Helped improving the architecture and pushing forward their KitchenOS platform

WeAreDecor. CTO & Co-founder. Affiliation marketplace with +500K products. Written in PHP & Laravel

21 Radio. Podcast and streaming app. iOS & Android. Written in Flutter

IZI Recording Together System app screenshot

IZI. Created native Android application for video recording and streaming. Kotlin, RxJava and WebRTC

UNANCOR. Marketplace of articles in digital media. Mentoring, code refactoring and automatic tests. Laravel and PHP

Ease Apps. CEO & Co-founder. Developed set of Android applications intended for people with disabilities

EVA Facial Mouse. Android webcam based mouse emulator. For the Vodafone Foundation using Java, C++ and OpenCV. +5M downloads

#ASPACEnet. Team lead. Project to bring the technology to people with cerebral palsy for +51 centers in Spain

La Muntanyeta – Cerebral Palsy Center. R&D. Created several applications and tools for people with cerebral palsy

Enable Viacam. Free & open source webcam based mouse emulator for Windows & Linux. Written in C++, OpenCV, wxWidgets.

GAMEABLING. Platform of games for people with cerebral palsy. Inspired in one of my projects. Funded by the European Commission with 1.3M€.

What they say about me

I would like to recommend Cesar Mauri, with whom I have worked on different projects at the Vodafone Foundation. During all these projects Cesar always demonstrated his involvement, commitment and ability both in the purely technical aspect of development / programming within the Android environment, and in his performance in more general areas such as analysis or management. Finally, I would also like to highlight his social skills that together with the aforementioned techniques allowed him to exceed expectations.

Tomás de Andrés

Innovation Department. Vodafone Business Spain

I have been working with César during 2023 at Fresco, in my role of Head of Mobile. He, as an android developer, has demonstrated very good tech skills during his collaboration. In addition, his proactivity helped a lot to the rest of engineers in making the right questions at the right time. He had a very good understanding about our complex architecture so he was quite efficient since the very beginning. César knowledge about unit testing, pull requests validation and Kotlin implementation was very strong and gave us the opportunity of maintaining our delivery velocity quite soon. He is a very good profesional with high level of commitment so definitely it was a very good decision to count with César in our team.

Carlos Abelenda Cuadrado

VP of Engineering. Web and Mobile at Fresco

We have collaborated with César in several android app development projects successfully. He is a responsible, serious and reliable person. He understands well the needs, raises reasoned solutions and develops applying design patterns, a clear architecture and good practices. And an interesting point to highlight is the reliability of the deliverables, applying unit tests and validating all possible casuistry.

Benjamín Murcia Sánchez

Head of Digital Products. Elecnor Deimos

Why a freelance?

Embrace freelance advantages:

  • Flexibility: No contracts, just tailored solutions. You gain access to flexible services tailored to your project’s specific needs. whether you require short-term assistance or ongoing support, I adapt to your timeline and requirements.
  • Specialized Expertise: Targeted skills for your project needs. As a seasoned software engineer, I bring a wealth of experience and expertise to the table. From coding to project management, I handle every aspect of your project with precision and skill.
  • Cost-Effectiveness: Skip overhead, get value for your investment. Say goodbye to the overhead costs associated with hiring full-time staff. As a freelancer, you only pay for the services you need when you need them, saving you money in the long run.
  • Scalability: Adapt to project demands effortlessly. Whether your project is in its infancy or reaching new heights of success, I scale my services to meet your evolving needs. From startups to established enterprises, I have the agility to adapt to any environment.
  • Personalized Attention: No intermediaries. When you hire me as your freelance software engineer, you’re not just another client – you’re a valued partner. I prioritize clear communication, transparency, and collaboration every step of the way to ensure your project’s success.
  • Fresh Perspective: Sometimes, an outsider’s viewpoint is just what your project needs to break through barriers and reach new heights. By hiring a freelance software engineer, you invite fresh ideas and innovative solutions into your team.

Myths about software developers and freelancing

  • Tech guys are often incapable of understanding business principles and have massive egos. Sure, some people might fit this profile. During my career, I designed, developed and marketed several products, I co-founded several startups as a CTO, and thus I am aware of the challenges the entire process entails. I like to get involved beyond programming helping and guiding my clients in all that I can. After all being a freelance means running a small business myself.
  • Freelance software engineers lack reliability and commitment. As a freelancer, I can’t afford to leave clients unsatisfied. Just check what they say about me, check my highlights, ask people I worked for. I am dedicated to delivering high-quality work on time, every time. With a proven track record of meeting deadlines and exceeding client expectations, I assure you of my commitment to your project’s success.
  • Freelance software engineers lack expertise and professionalism. Being worked all your career in a company or as a freelancer says nothing about your value of a developer. Check my projects. Check what others say about me. Check my reviews in freelancers platforms.
  • In-house developers provide a longer term commitment. I’ve had the opportunity of working with several clients repeatedly, and many of them have found it necessary to renew a significant portion of their development staff. Meanwhile, I have maintained ongoing collaboration with them.
  • Freelancers are not good team players. Throughout my career, I’ve seamlessly integrated into numerous client teams, actively participating in Agile ceremonies, code reviews, and collaborative brainstorming sessions.

Facing challenges?

  • Looking to advance your app with a future-proof architecture and test-driven development?
  • Need to optimize your codebase, automate testing, and guide your team in adopting industry best practices?
  • Had a bad experience with other developer o development shop?
  • Searching for a tech lead for your next big project?

Why quality matters?

Investing in quality when developing a software project is crucial for numerous reasons. It is relatively easy to create software that works, but it is much harder to create software that also can evolve over time and keep up with your needs. Making the things right from the beginning is the best way to protect your investment in the long term. Here are five key arguments supporting this approach:

  • Cost Savings: Quality software reduces long-term expenses by minimizing maintenance, debugging, and redevelopment costs.
  • Enhanced User Experience: High-quality software ensures a superior user experience, leading to increased user satisfaction and market competitiveness.
  • Faster Time to Market: Quality-focused development accelerates the process by detecting and addressing issues early, resulting in smoother progress and quicker product launches.
  • Scalability and Maintainability: Quality software is more scalable and maintainable, enabling businesses to adapt to changing requirements and technologies more effectively.
  • Reputation and Brand Integrity: Investing in quality reinforces a company’s reputation for excellence, fostering trust among customers and setting it apart from competitors.

For me quality and attention to detail are paramount. Therefore, when I get involved in a project, I focus on delivering a high-quality product that I can be proud of.


During my professional career I employed a number of technologies including C, C ++, Java, Kotlin, Flutter, Dart, PHP, Laravel, Python, SQL, .NET, Django, CSS, JavaScript, TypeScript, Angular, Spring Boot, computer vision, among others.