Java Software Engineer

Cactus is a software development company, providing full-cycle services for the European market. More than 170 companies increased business productivity using solutions developed by Cactus’ team. The company has been regularly included in the listings of the best software development companies in Belgium, where we have our HQ, and Europe.

Cactus is ready to expand the team with a

Software Engineer with strong expertise in Java

an AI mindset

at our

office in Seville. In this role, you will help to build and evolve some of the software platforms Cactus is engaged to, starting with a platform that enables

IoT connectivity in cities —from device onboarding and data ingestion to monitoring and operations at scale.

What You Will Do

Contribute to the continuous development of software products with real impact on cities.

Participate across the full development lifecycle : SCRUM ceremonies, backlog refinement, new features, and maintenance.

Build solutions that interact with hardware and other subsystems.

Identify bugs and risks, and propose effective technical solutions.

Take part in technical discussions to solve complex challenges.

Support the team and maintain technical documentation.

Mentor less experienced developers through code reviews and knowledge sharing.

What We Expect

5+ years

of hands-on software development experience.

Strong experience with

Java and Spring

is a MUST.

Experience or knowledge of message brokers (MQTT).

Experience with

microservices

Docker .

Solid database experience, including

PostgreSQL

time-series databases.

Experience with monitoring / metrics using

Prometheus

and dashboards in

Grafana.

Good engineering practices : testing, clean code, version control, documentation.

Interest in

IoT connectivity , networking basics, and distributed systems.

Continuous learning mindset , staying up to date with modern coding practices and actively leveraging

AI-assisted tools

across different phases of the software development lifecycle, while maintaining strong ownership and code quality.

Security mindset :

you build software with security in mind (secure coding practices, least privilege, safe handling of secrets), proactively identify risks and vulnerabilities, and collaborate to ensure services are robust and compliant.

Focus on incremental improvements and seamless customer experience.

Good communication skills in English and Spanish is a MUST.

• Nice to have :

JavaScript + React.

Familiarity with IoT protocols and ecosystems such as

LoRaWAN.

Knowledge of networking concepts (TCP / IP, routing fundamentals, gateways, firewalls).

Streaming pipelines, or high-volume telemetry systems.

What We Offer

We value spontaneous interaction, co-creation, and co-ideation. That’s why we believe in hybrid work, with regular time working together at the office.

A collaborative environment focused on ownership, growth, and impact.

An environment to keep the pace on AI assisted tools.

An open, international team of experts.

Competitive salary, benefits, and learning opportunities.

Flexible working hours : you own your work and how you organize it.

Get-together team events.