Case Study

API Services Modernization

Challenges
Project Journey
Results

Operations & Support Effort reduced from 89% to

33%

Development & Optimization Time improved from 11% to

67%

Waste Reduction Full focus on feature development

56%

LEAN-CODERS has been modernizing the API services of the Vienna Tourism Board since 2023 – a legacy system landscape with high technical debt.

Legacy replacement - Quality assurance - Communication & planning structure

The result: a stable, scalable API on wien.info, the IVIE app, and the B2B partner portals running reliably – and a collaboration with the WTV and another external IT service provider that is continuously improving.

Challenges

Backend landscapes that have organically grown over the years bring typical challenges.

High Technical Debt

With the growth of the platform, the codebase had also grown – new features and bug fixes became increasingly complex.
Test strategy with expansion potential

The existing tests covered the API fundamentals. Automated safeguarding of the business logic was the next logical step.
Requirements management and planning structures

In rapidly growing teams, the focus is naturally on speed. Together, we established structured processes and roadmap planning.
Collaboration and shared work culture

Every new development partnership takes time. We invested early in shared rhythms and communication formats.
Tech Stack Modernization

The existing stack was pragmatic and suitable for the previous phase. With increasing demands, the switch to standards like TypeScript or Keycloak became appealing.

Project Journey

Assessment & building trust

The first step was listening and understanding. We analyzed the system, mapped technical debt, and together with the WTV team created initial structures: clear responsibilities, a revised working mode, optimized Jira processes, and an initial testing concept.

In parallel: building mutual trust – the foundation for everything that followed.

Stabilization & quality assurance

Improvement of the Swagger documentation, establishment of a comprehensive testing strategy. Technical debts are made visible, prioritized, and reduced in controlled steps. From symptom treatment to structured root cause analysis.

Modernization of the Tech Stack

Migration from JavaScript to TypeScript for more type safety and fewer hard-to-find errors. Optimization of the synchronization logic to the source systems of the data. Introduction of Keycloak as a professional identity service – instead of a self-built auth system in Go.

Partnership & shared growth

Establishment of joint planning and communication structures, regular team retrospectives, joint team events. A client-service provider relationship transforms into a true partnership. My Vienna emerges – a sign of the growing trust between the teams.

Scaling & continuous improvement

The focus shifts: from operations & support clearly towards development and optimization. The platform is actively expanded with new features, and the budget for further development increases. LEAN-CODERS becomes a strategic partner for the platform's further development.

Results

The most significant result of our work can be seen in the shift in how the team spends its time:

Operations & Support 69% -> 14%

Optimization & Development 31% -> 86%

In 2023, almost 70% of the capacity was spent keeping the system running. By 2025, it will be only 14%. What previously tied up resources now gives room for real further development.

Stability & Quality

Replacement of existing systems: cleaner architecture, better traceability

PR process introduced: code reviews as standard, no uncontrolled changes anymore

Tech Stack Modernization

Migration from JavaScript to TypeScript: type safety, fewer hard-to-find errors, more consistent code

Replacement of the self-built Go auth service with Keycloak: professional identity management, maintainable and scalable

Processes & Collaboration

Strong focus on requirements engineering aimed at increasing ticket quality

Roadmap, prioritization, and structured planning established as work standards

Regular retrospectives and team events as part of the shared work culture

Scaling

Team growth from 1.5 to 3.5 LEAN-CODERS employees during the project

Budget for active further development increases – shift from support to feature development

LEAN-CODERS as a strategically integrated partner: free hand in technical decisions

Long-term partnership

Since 2023 – ongoing. The collaboration with the WTV is not a completed project, but a growing partnership.

LEAN-CODERS is not just a technical service provider but has actively contributed to the work culture, planning structure, and communication at the WTV.

This is rare – anda true success story.