Java Software Developer – Core Telco | Budapest Hybrid

We are looking for an experienced Java Software Developer for a long-term Core Telco project in Budapest.

This is a hands-on development role in a complex, business-critical telecommunications environment. You will work with existing and modernized services, integrations, APIs and legacy components across a distributed

system landscape.

Important

This role is open only to candidates currently based in Hungary and able to work from the Budapest office 2 days per week.

Remote applications from outside Hungary cannot be considered.

Project details

• Domain: Telecommunications / Core Telco
• Location: Budapest, Hungary
• Work model: Hybrid – 2 days/week in the Budapest office
• Engagement: Full-time contractor / freelancer
• Start: October 2026
• Contract: Until December 2027
• Long-term project: 1+ year

Key responsibilities

• Analyze, understand and extend existing Core Telco services and legacy code
• Work with dependencies across multiple repositories
• Design, develop and maintain clean, testable and reliable Java-based services, microservices and APIs
• Work with existing PHP-based services where required
• Develop and modernize integrations and asynchronous data flows using REST/OpenAPI, Kafka, messaging and related technologies
• Write unit and integration tests
• Participate in code reviews and maintain concise technical documentation
• Troubleshoot defects using logs, traces and production-like environments
• Perform root-cause analysis and implement sustainable fixes
• Work closely with Lead Developers, Architects, DevOps, integration specialists and external vendors
• Take ownership of assigned components from development through delivery

This closely follows the original responsibilities, including legacy analysis, Java/PHP services, REST/OpenAPI, Kafka/messaging, testing and production troubleshooting. Developer - Core Telco

Mandatory requirements

• 3+ years of professional software development experience
• Strong hands-on Java development experience
• Practical experience with Spring Boot and/or Quarkus
• Experience developing microservices
• Strong REST API / RESTful services experience
• Git
• Experience with automated testing
• Experience working with CI/CD pipelines
• Experience with containerized application delivery
• Understanding of distributed systems
• Experience with or good understanding of messaging / streaming technologies such as Kafka or RabbitMQ
• Good analytical and problem-solving skills
• Good professional English

These are the core requirements explicitly reflected in the original Developer specification. Developer - Core Telco

Strong advantage

• Professional PHP development experience
• Telecommunications experience
• BSS / OSS
• Core Telco / Core Network
• Experience working with large legacy codebases
• High-availability or other business-critical enterprise environments
• Production troubleshooting using logs and traces

If you are interested, please send your CV and hourly rate expectation to viktor.zala@altshift.hu or contact me via DM.

Please apply only if you are currently based in Hungary and can attend the Budapest office twice per week.

#Java #SpringBoot #Quarkus #Microservices #RESTAPI #Kafka #SoftwareDeveloper #JavaDeveloper #Telco #Telecommunications #BSS #OSS #Budapest #Hungary #Contractor