Tech Lead / Senior Java Software Engineer

1oT is looking for a Tech Lead / Senior Software Engineer to join us in building connectivity solutions according to the new eSIM IoT standard.

1oT has built a platform for helping global IoT service providers manage their SIM cards and billing. The self-service based platform enables users to control and monitor SIM card sessions, switch SIM cards on/off, buy new SIMs, send SMS to the SIM, etc. Our client portfolio ranges from e-mobility to asset tracking to smart city solutions, so you will have interaction with a variety of IoT sectors and telecom companies. 

eSIM team builds and maintains services that implement at 1oT the eSIM standard of GSMA.

Number of vacancies

1

Deadline for applying

31.12.2025

Job location

Tallinn

Work assignments

What you'll do:


  • Develop large-scale services ( Java / REST / Spring / SQL )
  • Contribute to back-office UI ( Vue.js )
  • Run and maintain our services in AWS ( Terraform / Docker / Grafana )
  • Lead discussions on the architecture of the platform
  • Identify bottlenecks in technical solutions of the team
  • Lead implementation of technical initiatives
  • Prioritize security and compliance in development initiatives
  • Mentor junior members of the team on best practices and ways of working
  • Ensure that eSIM services are built according to GSMA specs
  • Handle external integrations via APIs

Education

A degree in Computer Science or a related field is beneficial but not mandatory. Strong practical experience is valued more highly.

Work experience

What you'll bring:


  • 6+ years of development experience (Java / REST / Spring / SQL)
  • Previous experience as Senior Engineer, Solution Architect, or Tech Lead
  • Experience with cloud-hosted services (AWS / Azure / GCP)
  • Familiarity with modern UI frameworks is a huge plus
  • Experience with cryptography or HSM is a huge plus

Personal qualities

You're a good fit if you..


  • enjoy working as part of a team and like driving technical discussions forward
  • approach challenges with a problem-solver mindset and get things done
  • take strong ownership of your work and manage yourself well
  • have the curiosity and hunger to build products that don't yet exist


Language skills

English

Additional requirements

Ability to work with APIs and integrations

Comfortable with security-focused development

Willingness to mentor and guide other engineers

Readiness to take ownership of technical domains

Company/organization offers

What we offer:


Meaningful, globally impactful work on cutting-edge eSIM technology

Diverse tasks from building new features to optimizing existing systems

Influence and ownership inside a growing, sustainable company

Cozy and productive environment in Tallinn HQ

Ambitious teammates who challenge the status quo

Supportive, fun team and great vibes

Technical EngineeringInformation Technology
  • Work time: Full time work
  • Workload: 1
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