You're seeing this page as if you were . The main menu is still yours, though. Exit from immersion
Malt Strategy
New report
Malt Tech Trends 2026
David Sierra FernandezDS

David Sierra Fernandez

Symfony Backend Developer

€300/day
Sabadell, ES
8-15 years
Symfony
PHP
MySQL
Backend Development
Software Engineering

Average response time: 1 hour

Freelancer profile translated to English.
Back to original language

About David

I am a backend developer specializing in Symfony, with experience in maintaining, evolving, and modernizing existing applications.

I help companies improve systems that are already in production, solving real problems such as:
- Slow or buggy applications
- Legacy code that is difficult to maintain
- Migrations between Symfony versions

I work mainly with:
- Symfony (2, 3, 4, 5, 6)
- PHP
- MySQL
- Docker (development and deployment environments)

I can help you if you need to:
✔ Fix bugs in an existing application
✔ Improve performance
✔ Migrate your project to more modern versions
✔ Develop new features

I focus on clean code, maintainable solutions, and clear communication with the client.

Available for one-off projects or ongoing collaboration.

  • Spanish

    Native or bilingual

  • English

    Conversational

  • Catalan

    Native or bilingual

Remote only
Primarily works remotely

Experience

  • Infinitum Digital Transformation SL
    Web App Developer
    January 2017 - Today (9 years and 7 months)
    Sabadell, Spain
    Backend developer specializing in Symfony, participating in the development, maintenance, and evolution of web applications in production.

    For over 8 years, I have worked on real business-oriented projects, responsible for:
    - Development of new features in existing applications
    - Maintenance and improvement of legacy systems
    - Optimization of performance and MySQL queries
    - Incident resolution in production environments
    - Integration of APIs and external services

    I have worked with complex applications where it is crucial to quickly understand existing code and propose stable and maintainable solutions.

    Main stack: Symfony, PHP, MySQL
    MySQL Symfony PHP Docker Migrations
  • Tenvinilo.com
    Web App Developer
    August 2016 - November 2016 (3 months)
    Sabadell, Spain
    Development and improvement of features on a web platform focused on e-commerce.

    Responsibilities:
    - Implementation of application improvements
    - Optimization of existing processes
    - Technical support and incident resolution

    Experience in environments focused on end-customers and platform performance.
    PHP Symfony Backend Development
  • BCNBIT
    Web Application Developer
    February 2016 - August 2016 (6 months)
    Sant Cugat, Spain
    Development of web applications in PHP, participating in different projects and adapting to various technical requirements.

    Main functions:
    - Backend functionality implementation
    - Working with MySQL databases
    - Application support and maintenance

    Key stage for consolidating knowledge in web development and best practices.
    MySQL Symfony PHP
Check out David's experience

Recommendations

Be the first to recommend David

Help this freelancer shine by sharing your experience working together.

These freelancer profiles also match your criteria

AgathaA

Agatha Frydrych

Backend Java Software Engineer

4.7

(3)

2

BaptisteB

Baptiste Duhen

Fullstack developer

4.6

(4)

5

AmedA

Amed Hamou

Senior Lead Developer

4

(2)

7

AudreyA

Audrey Champion

Web developer

4.3

(3)

4

Signup to reveal

Education

  • DAW (Web Application Development), Higher Level Vocational Training in Computer Science
    Nicolau Copernic Institute
    2014
    DAW (Desarrollo Aplicaciones WEB), Ciclo Formativo Grado Superior en Informática

Categories