Hire the Best Java Developers
in Spain
Barcelona, Spain
Need someone who can build, stabilize and scale your Android product? You just found him 🤝 📊 12+ years in mobile delivery 📊 20+ Android-focused projects 📊 10+ years supporting regulated and business-critical products 📊 Experience with compliance-ready apps, secure payments, backend-heavy systems and Software Development I help companies create secure, maintainable, high-performance apps for Healthcare, FinTech and consumer products. Core Expertise 🔹 Native Android engineering with modern architecture and Software Design 🔹 Kotlin-first development with maintainability in mind 🔹 Legacy modernization from Java to Kotlin 🔹 Secure integrations, performance tuning, release stability 🔹 Product delivery for Healthcare, FinTech, consumer platforms and Mobile App Development I’m an android developer focused on products where reliability and clean architecture matter. As a kotlin developer, I build scalable solutions with android kotlin best practices, Jetpack tooling and AOSP awareness. Clients come to me for android developer kotlin expertise when they need stability, lower technical debt and growth. I work as an android app developer on products that need more than interface implementation. I support teams with android app development for secure solutions where every android app stays maintainable after launch. My background: improving an android application used by thousands of users, integrating backend systems, payment flows, and healthcare-grade data handling. That is why companies hire me as an android mobile developer ( android mobile app developer ) when they need delivery. What I Do Best ✅ Android development using Kotlin and Java ✅ Architecture design with MVVM, Clean Architecture, modularization ✅ Backend communication, authentication and payment integrations ✅ Performance optimization, debugging, maintenance and release support ✅ Application Improvement for live mobile products ✅ Solo delivery or collaboration inside a larger team My strongest specialization is android developer kotlin work. I often join teams that need android developer kotlin java skills to modernize legacy code, migrate modules, and improve release quality without a full rewrite. That work benefits from practical experience as a java developer and from thinking like an android kotlin developer who can handle new features and stabilization. Relevant Experience Highlights 🔸 Healthcare mobile applications with compliance-aware architecture 🔸 Performance optimization and crash-rate reduction 🔸 Secure data handling and app stability improvements 🔸 Secure apps with payment integration and transaction-safe flows 🔸 Backend integrations with PHP, Python, JavaScript, and REST APIs 🔸 Collaboration with iOS, backend, QA, and web teams 🔸 Ability to scale from one engineer to a delivery team I also have experience with android ble and android bluetooth features for pairing flows and reliable data exchange. Whether I contribute to an android mobile app or support an existing codebase as a mobile developer, I focus on release readiness. Tech Stack 🔸 Android kotlin with Jetpack, Compose, Android SDK, AOSP 🔸 Java, Firebase, secure cloud services, CI/CD 🔸 REST APIs, secure auth, payment gateways 🔸 Node.js, JavaScript, C#, SQL for backend alignment 🔸 Git, Android Studio, release workflows, crash analysis 🔸 MVVM, Clean Architecture, modular apps, scalability-first mindset My work is rooted in native Android, but I also understand broader product ecosystems. I collaborate effectively as an ios developer ( ios app developer ) when cross-platform alignment matters, including iOS Development discussions with teams using Swift. I have worked alongside teams using react native and reviewed delivery implications where flutter developer was involved, though I do not present those as my core specialization. That exposure helps me operate as an android developer and product-minded mobile app developer within cross-functional teams. Team & Product Collaboration 🔹 Coordination with a rest api developer 🔹 Alignment with web application development 🔹 Communication with a web developer or front end developer 🔹 Familiarity with database builder, django, and python automation Support I Can Provide ✔️ Build a mobile app from scratch ✔️ Join an existing product as an app developer android ✔️ Refactor legacy code and modernize architecture ✔️ fix android application bugs and improve release readiness I do not position myself as a wordpress, magento, game developer or unreal engine specialist and I do not use unrelated positioning such as android developer india. Even when someone types android develoer, they usually need a senior specialist who can take ownership. I built mobile applications for autism-related projects with intuitive user experience. 📬 If you need an android developer who can improve an existing product, build a reliable solution from scratch or support growth with kotlin developer depth, send me a message.
- Java
- Android
- AOSP
- Kotlin
- Mobile App Development
- Flutter
- Node.js
- Android App Development
- Swift
- Firebase
- iOS Development
- PHP
- JavaScript
- React Native
- C#
- SQL
- Software Design
- Application Improvement
- Software Development
- Software Debugging
Alicante, Spain
Backend Engineer (Java/Spring/AWS) helping startups move faster and fix backend issues. I help startups build and improve backend systems - from shipping new features fast to fixing performance and stability issues. I work mainly with Java (Spring Boot), PostgreSQL, Redis, and AWS, and I’m comfortable taking ownership of backend parts from API design to production deployment. Currently available for part-time work (10-20h/week), can start immediately. Recent results: • Reduced report latency from seconds to sub-second using Redis caching (TTL + watermark) • Led migration from Okta to Auth0 across multiple microservices • Built a B2B marketplace backend (Postgres + Elasticsearch) handling thousands of products with stable search I can help you with: • Building new backend features quickly • Stabilizing and improving an existing system • Fixing performance issues (DB queries, APIs, latency) • Designing clean and scalable backend architecture • Integrating external services and APIs I focus on writing clean, maintainable code and delivering solutions that work reliably under real-world load. If you need someone who can jump in and deliver quickly - feel free to reach out.
- Java
- Hibernate
- Spring Boot
- Spring Framework
- Docker
- Gradle
- SQL
- RESTful Architecture
- AWS Development
- CI/CD
- Redis
- Microservice
- Elasticsearch
- Performance Optimization
Valencia, Spain
Hi! I’m Bogdan — a Mobile Developer & Product Strategist with 15+ years of experience helping startups and enterprises bring ideas to life through clean code, smart design, and measurable results. I lead a European development team recognized by Clutch among: 🏆 Top 100 Mobile Development Teams in Europe 🏆 Top 30 Flutter Developers What You Get I focus on building products that are fast, stable, and user-loved — not just apps. Clients come to us when they need to: ✅ Turn an idea into a working MVP in 6–8 weeks ✅ Rebuild or scale an existing mobile app ✅ Integrate AI assistants, chatbots, or recommendation engines ✅ Improve UX and retention through research and design Tech Stack Mobile: Flutter, Swift, Kotlin, React Native Backend: Java, Python, PHP (Laravel), Django, Firebase AI & Automation: OpenAI API, LangChain, custom LLMs Design: Figma, Adobe Suite, UX research, prototyping Our Process 1) Discovery & Scoping – align tech and business goals 2) Design & Development – transparent weekly sprints 3)Testing & Launch – QA, analytics, and release support 4) Post-launch support – flexible maintenance and scale-up Why Clients Choose Us ⭐ Fast & proactive communication (no agency bureaucracy) ⭐ Transparent time tracking (Upwork hourly or milestone) ⭐ Stable European team — not freelancers on rotation ⭐ Code ownership 100% belongs to you Let’s build something your users will love — and that actually moves your business forward. Send a quick message with your idea or challenge, and I’ll reply within a few hours.
- Java
- Spring Boot
- Web Development
- Flutter
- Augmented Reality
- Firebase
- Mobile App Development
- React Native
- Android
- iOS Development
- Click-to-Call
- Dart
- UX & UI
- Mobile App
- AWS Lambda
Madrid, Spain
Shipped multiple web games, solo, from concept to production. Built with TypeScript/JavaScript and PixiJS/Phaser.js lean by design, fast to load, zero-lag input. Full cross-device support: keyboard, mouse, and touch, with smart layout adaptation for any screen size or aspect ratio. I own the whole process: mechanics, graphics, animation, effects, deployment.
- TypeScript
- HTML5
- JavaScript
- Game Development
- Game Design
- Mobile UI Design
- Node.js
- PixiJS
- HTML5 Canvas
Salinas, Spain
DevOps, and Marketplace Customizations/Integrations (Shopify, Amazon, Ebay, BigCommerce). Odoo Consultant and Developer. Expertise in Emerging Technologies: * Automation & DevOps: Streamline operations with Docker, AWS, Google Cloud. * Expertise in CI/CD pipelines, server management, and infrastructure as code. * Data Analysis & Machine Learning: Advanced skills in Python for data analysis, modeling, and machine learning, leveraging a dissertation project in this field. Skilled in creating actionable insights from complex datasets. * AI-Powered Solutions: Integrating AI tools and APIs to enhance user experiences, automate workflows, and improve performance in e-commerce platforms. Odoo Consultant and Developer: Extensive experience as a consultant and developer with the Odoo ERP platform, specializing in creating custom modules tailored to specific business requirements, seamless integration with external systems (including CRM, accounting, and inventory management). Marketplace Development Specialist: * Shopify Expert: Store setup, advanced customizations, app development, SEO optimization, liquid template customizations, and platform migrations. * Amazon & eBay Integrations: Proficient with Amazon MWS, SP API, Advertising API, eBay API, and BigCommerce API for seamless integrations and automation. Tech Stack Highlights: * Backend: Java / Spring Boot / Node.js / Python * Frontend: Vue.js / React.js * Mobile Development: React Native (iOS & Android) * DevOps Tools: Docker / AWS / Google Cloud / CI/CD Pipelines * Machine Learning: Python (NumPy, Pandas, scikit-learn, TensorFlow) * Database: MongoDB / SQL / Data Pipelines * Scripting: Bash / Shell Scripts / OAuth Integration Why Choose Me? I bring over 20+ years of experience as a Computer Science Engineer, blending expertise in software development. My passion lies in leveraging the latest technologies to solve complex challenges and drive measurable results for clients. I have a degree in Computer Sciences.
- Java
- Shopify
- MongoDB
- Vue.js
- Ecommerce Website
- Node.js
- React
- Shopify Templates
- Amazon Web Services
- Amazon MWS
- API
- RESTful API
- eBay API
- Ecommerce Website Development
Valencia, Spain
Professional Summary • 12+ years developing JEE solutions for banks. Working mainly with those technologies: Java, Spring-boot , Spring MVC, Spring Security.... These applications work under MySQL, SQLServer, and Oracle databases; • 5+ years of designing and developing Restful microservices. • 3+ years of hands-on experience integrating SOAP Web Services, XML, and XSD systems. • 8+ years using Scrum in the software development process, where 3 of those years as Scrum Master; • 7+ Working experience designing, developing, and managing Java applications at AWS and/or Kubernets/Openshift cloud. • The main application container so far was Apache Tomcat, but I also had experience with JBoss and Websphere environments. Main skills: • Proactive, always aim to contribute to team objectives; • Focused on results without losing the quality sense; • Take problems ownership; • Flexible Other tools • Bug Tracking: JIRA, Redmine • Tests and Performance Analysis: Apache Jmeter, SoapUI • Version control: GIT,SVN • Others: IntelliJ, Maven, Eclipse
- Java
- Hibernate
- Software Architecture & Design
- Spring Framework
- AWS Development
- OpenShift
- Kubernetes
- Microservice
- API Development
- RESTful API
- RESTful Architecture
- SQL
- MySQL
- Grafana
- Prometheus
How it works
Post a job for free Post a job
Tell us what you need. Create your own job post or generate one with AI then filter talent matches.
Hire top talent fast
Consult, interview, and hire quickly, so you can meet the freelancers you're excited about.
Collaborate easily
Use Upwork to chat or video call, share files, and track project progress right from the app.
Payment simplified
Manage payments in one place with flexible billing options. Only pay for approved work, hourly or by milestone.
Don't just take our word for it
“Upwork provides an umbrella-level of security. I can see a talent’s work history and ratings. I can hold payments in escrow. I can communicate through Upwork Messages instead of working through my email address.”
Kim Darling
Emerald Tiger
“Upwork is the best platform to hire skilled professionals when we're not looking for a full-time employee. All the companies in our portfolio use Upwork to find talent across a wide range of fields.”
David Merry
Kinetic Investments
“Our very specific requirements can be a challenge—With Upwork, we’re able to access a bigger community to ensure the success of our projects.”
Katja Krohn
Summa Linguae
Resources to help you hire

Cost to hire a Java Developer
Explore typical Java Developer rates and what businesses pay to hire top talent.

Java Developer job description template
Get tips to write a job post that attracts qualified Java developers.

Java Developer interview questions
Top interview questions to help you hire the right Java developers, faster.
Resources to help you hire

Cost to hire a Java Developer
Explore typical Java Developer rates and what businesses pay to hire top talent.

Java Developer job description template
Get tips to write a job post that attracts qualified Java developers.

Java Developer interview questions
Top interview questions to help you hire the right Java developers, faster.
How do I hire a Java Developer in Spain on Upwork?
You can hire a Java Developer in Spain on Upwork in four simple steps:
- Create a job post tailored to your Java Developer project scope. We'll walk you through the process step by step.
- Browse top Java Developer talent on Upwork and invite them to your project.
- Once the proposals start flowing in, create a shortlist of top Java Developer profiles and interview.
- Hire the right Java Developer for your project from Upwork, the world's largest work marketplace.
At Upwork, we believe talent staffing should be easy.
How much does it cost to hire a Java Developer?
Rates charged by Java Developers on Upwork can vary with a number of factors including experience, location, and market conditions. See hourly rates for in-demand skills on Upwork.
Why hire a Java Developer in Spain on Upwork?
As the world's work marketplace, we connect highly-skilled freelance Java Developers and businesses and help them build trusted, long-term relationships so they can achieve more together. Let us help you build the dream Java Developer team you need to succeed.
Can I hire a Java Developer in Spain within 24 hours on Upwork?
Depending on availability and the quality of your job post, it's entirely possible to sign up for Upwork and receive Java Developer proposals within 24 hours of posting a job description.
Find more freelancers
Top cities for Java Developers in Spain
- Chatbot Developers in Barcelona, ES
- Zoho CRM Developers in Barcelona, ES
- Web Designers in Madrid, ES
- Web Designers in Barcelona, ES
- Data Scientists in Barcelona, ES
- Pages Specialists in Barcelona, ES
- Localization Specialists in Valencia, ES
- Graphic Designers in Malaga, ES
- Graphic Designers in Barcelona, ES
- Recruiters in Madrid, ES
- Social Media Managers in Barcelona, ES
- Invitation Designers in Barcelona, ES
- Aviation Specialists in Barcelona, ES
- Product Photographers in Barcelona, ES
- Translators in Madrid, ES
- Translators in Las Palmas de Gran Canaria, ES
More top skills in Spain
- PHP Developers in Spain
- Django Developers in Spain
- Outsourced Developers in Spain
- C++ Programmers & Developers in Spain
- TypeScript Developers in Spain
- Embedded C Programmers & Developers in Spain
- Node.js Developers in Spain
- Cocoa Developers in Spain
- Blockchain Developers in Spain
- Programming Languages Freelancers in Spain
- React Native Developers in Spain
- JavaScript Developers in Spain
- Unity Developers in Spain
- Adobe Flash Specialists in Spain
- Microservices Developers in Spain
- Android Developers in Spain