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# Backend Senior Developer - Core Squad

- **Company:** Otto Group
- **Location:** Madrid, Spain (Remote available)
- **Salary:** €72,800.0 - €114,400.0
- **Contract:** Permanent contract
- **Skills:** Java (Programming Language), JavaScript (Programming Language), .NET Framework, Application Programming Interfaces (APIs), Agile Methodology, Amazon Web Services, User Authentication, Distributed Systems, OAuth, Data Streaming, Wireless Networks, File Transfer Protocol (FTP), ReactJS, Delivery Pipeline, SOAPAPI, Backend, Vue.js, Information Technology, Front End Software Development, Software Coding, Restful APIs, Golang, Programming Languages
- **Published:** September 24, 2026
- **Apply:** https://www.adzuna.es/contact-us.html

## About the Role

+ 3+ years of experience working as a Senior Backend Developer.
 + Strong computer science foundations, mostly working in distributed systems.
 + Extensive experience writing scalable APIs using REST architecture.
 + Extensive experience designing even driven architectures using queues, streaming, etc.
 + Experience writing code in Golang programming language.
 + Experience working in AWS cloud environment.
 + Experience working in Agile environments.
 + Experience in some older technologies such as CLIs, SOAP services, FTP, etc.
 + Experience working in a multicultural, multidisciplinary environment.
 + Fluent in both written and spoken English.
 + Familiar with API and WebApps security standards and authentication methods (API key, JWT token, OAuth 2.0, etc).
Preferred skills and experience:

 * Bachelor degree in Computer Science, Mathematics or equivalent.
 * Experience in other programming languages like Java, .NET or Javascript.
 * Experience writing IaC scripts and managing CI/CD pipelines.
 * Familiar with Frontend technologies such as Vue.js or React.js.
 * Experience communicating with stakeholders and/or customers.
 * Experience integrating with core Telecommunications platforms such as OCS, BSS, PGW, PCRF and equivalent across 3/4/5G generations as used by MNO/MVNOs
 * Extensive knowledge about mobile networks and telephon