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I am a results-driven software developer with extensive experience building, optimizing, and modernizing data-centric applications in financial and enterprise settings. I specialize in C#, .NET, SQL Server, and Oracle, and I have a proven track record turning legacy systems into scalable, maintainable, and performance-driven solutions. I collaborate closely with product, QA, and business teams in Agile environments to deliver stable, secure, and user-focused software that supports high-volume transactional workflows and business growth. I also enjoy mentoring teams, refactoring codebases, and automating processes to reduce manual workload and operational risk.…I am a results-driven software developer with extensive experience building, optimizing, and modernizing data-centric applications in financial and enterprise settings. I specialize in C#, .NET, SQL Server, and Oracle, and I have a proven track record turning legacy systems into scalable, maintainable, and performance-driven solutions. I collaborate closely with product, QA, and business teams in Agile environments to deliver stable, secure, and user-focused software that supports high-volume transactional workflows and business growth. I also enjoy mentoring teams, refactoring codebases, and automating processes to reduce manual workload and operational risk.

Johan Visser

Programmer, Developer, Back-End Developer, +3

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I am a results-driven software developer with extensive experience building, optimizing, and modernizing data-centric applications in financial and enterprise settings. I specialize in C#, .NET, SQL Server, and Oracle, and I have a proven track record turning legacy systems into scalable, maintainable, and performance-driven solutions. I collaborate closely with product, QA, and business teams in Agile environments to deliver stable, secure, and user-focused software that supports high-volume transactional workflows and business growth. I also enjoy mentoring teams, refactoring codebases, and automating processes to reduce manual workload and operational risk.…I am a results-driven software developer with extensive experience building, optimizing, and modernizing data-centric applications in financial and enterprise settings. I specialize in C#, .NET, SQL Server, and Oracle, and I have a proven track record turning legacy systems into scalable, maintainable, and performance-driven solutions. I collaborate closely with product, QA, and business teams in Agile environments to deliver stable, secure, and user-focused software that supports high-volume transactional workflows and business growth. I also enjoy mentoring teams, refactoring codebases, and automating processes to reduce manual workload and operational risk.

Available to hire

I am a results-driven software developer with extensive experience building, optimizing, and modernizing data-centric applications in financial and enterprise settings. I specialize in C#, .NET, SQL Server, and Oracle, and I have a proven track record turning legacy systems into scalable, maintainable, and performance-driven solutions.

I collaborate closely with product, QA, and business teams in Agile environments to deliver stable, secure, and user-focused software that supports high-volume transactional workflows and business growth. I also enjoy mentoring teams, refactoring codebases, and automating processes to reduce manual workload and operational risk.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Language

English

Fluent

Dutch

Fluent

Work Experience

Software Developer at H&T Pawnbrokers

June 1, 2018 - September 1, 2025

Designed, maintained, and enhanced enterprise-grade C# / WPF applications using the MVVM pattern to support loan origination, renewals, and customer account servicing; improved operational consistency and reduced input handling errors by over 30% across 150+ daily users. Performed complex SQL Server development including query refactoring, index optimization, stored procedure tuning, and data consistency validation, reducing reporting runtime from minutes to under 10 seconds and accelerating management decisions. Led modernization of legacy Delphi-based platforms into stable, scalable .NET-based solutions, improving system reliability and reducing downtime by 25% across branches. Developed automated reconciliation and data correction tools to replace manual multi-hour financial balancing tasks, enabling back-office teams to complete key workflows in minutes and reduce risk of human error.

Software Developer at IRESS

November 1, 2016 - May 1, 2018

Built and enhanced C# / WPF reporting and workflow management tools used across finance teams to consolidate data, visualize monthly performance, and streamline reporting tasks previously done via spreadsheets or manual extraction. Restructured and indexed Oracle database tables, views, and stored procedures to improve data retrieval efficiency, resulting in a 40% increase in query speed and smoother month-end operations. Diagnosed and resolved recurring reporting latency, data mismatches, and stability issues by performance profiling, error investigation, and targeted code optimizations. Collaborated with business analysts and QA to document requirements, validate use cases, and deploy enhancements aligned to business reporting needs and regulatory standards.

Senior Developer & Assistant Scrum Master at CENTRIC

January 1, 2001 - November 1, 2016

Led multi-year modernization efforts migrating Delphi desktop applications to C# WinForms, introducing modular architecture, reducing technical debt, and lowering long-term maintenance costs by 35%. Improved reliability and performance of enterprise datasets across Oracle and SQL Server by refining data models, restructuring schema relationships, implementing stored procedure logic, and tightening validation rules—reducing production data integrity issues by 20%. Supported Agile delivery as Assistant Scrum Master by facilitating sprint planning, backlog prioritization, stand-ups, and retrospectives, improving team predictability and reducing delivery overruns by 15%. Enhanced reporting by optimizing Crystal Reports data extracts and report templates, eliminating redundant ad-hoc reporting workloads for analysts by 25%.

Software Developer at Essentium

June 1, 1996 - December 1, 2000

Designed, coded, and maintained Delphi-based administrative and financial applications with a focus on accurate data processing, stable core logic, and structured error handling for reliable daily business operations. Strengthened data integrity by implementing validation routines, improving exception handling, and refining field-level business logic—yielding a 20% improvement in transaction and data accuracy. Delivered maintainable, well-structured codebases with consistent documentation and modular component design to ensure long-term adaptability. Collaborated with analysts and operational teams to gather requirements, translate workflows into software logic, deploy incremental improvements, and perform root-cause analysis for support requests.