Jani Järvinen, Developer in Vantaa, Finland
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Jani Järvinen

Verified Expert  in Engineering

Software Developer

Vantaa, Finland
Toptal Member Since
July 29, 2021

Jani is an experienced and certified software development professional with over 20 years of experience in Microsoft technologies, cloud services, and web application development. In addition, Jani is well aware of system security, DevOps, project management, and databases. Jani has also authored six software development books as well as worked as a trainer in various technologies.


Visual Studio, C#, XML, Electronic Data Interchange (EDI), SOAP...
ASP.NET, ASP.NET MVC, ASP.NET Web API, Azure, Visual Studio, C#...
ASP.NET, Azure, Microsoft SQL Server, Azure SQL, Visual Studio, C#, LINQ...




Preferred Environment

Windows, Visual Studio, ASP.NET MVC, Web API, .NET Core, .NET 5, C#, Microsoft SQL Server, Azure, Entity Framework

The most amazing...

...thing was designing the architecture and a public Web API for a real-time video management system (ASP.NET, C#, SQL Server); it's now available in 40 countries.

Work Experience

Senior Lead Developer

2019 - PRESENT
  • Took over the in-house implementation of a large-scale integration solution using XML, CSV, EDI, and SOAP.
  • Managed a small team of developers and testers using Monday.com project management software.
  • Set up a production environment for future automatic deployment in a DevOps manner.
Technologies: Visual Studio, C#, XML, Electronic Data Interchange (EDI), SOAP, Microsoft SQL Server, NServiceBus, RabbitMQ, Monday.com, DevOps, .NET 5, Unit Testing, Data Integration, System Integration Testing (SIT), Technical Leadership, APIs, SQL, Blazor, CSS, HTML, Microsoft Stack, Windows UI, XSD, XML Web Services, Integration

Senior Developer

2012 - 2021
  • Designed, architected, and developed and .NET (C#/VB.NET) web application using ASP.NET to serve the public in Finland; this included designing and implementing a 200GB database using SQL Server.
  • Managed a team of six members, including in-house developers.
  • Set up the production environment and launched the application to the public.
Technologies: ASP.NET, ASP.NET MVC, ASP.NET Web API, Azure, Visual Studio, C#, Visual Basic .NET (VB.NET), Microsoft SQL Server, Jira, .NET 5, APIs, Technical Leadership, .NET, JavaScript, SQL, Blazor, CSS, HTML, Microsoft Stack, Telerik, Windows UI, XSD, XML Web Services, Integration

Senior Developer

2016 - 2020
  • Architected and developed with a team a web-based MES application for a meat processing plant.
  • Tracked requirements and bugs using Azure DevOps servers while operating under an Agile Scrum methodology; also managed a team of 20 developers and testers.
  • Installed the first working version into production for the client.
Technologies: ASP.NET, Azure, Microsoft SQL Server, Azure SQL, Visual Studio, C#, LINQ, Entity Framework, .NET Core, .NET, JavaScript

Senior Developer

2017 - 2019
  • Developed a public ASP.NET Web API application using C# and SQL Server for a complex video surveillance system. The Public API can be used to control the system and view realtime video streams.
  • Designed the application architecture and initial version; later versions were developed by in-house developers.
  • Automated the system testing process using PowerShell and Microsoft Hyper-V; also developed the automatic testing scripts.
Technologies: ASP.NET Web API, OAuth 2, C#, Microsoft SQL Server

Senior Developer

2016 - 2019
  • Developed a UWP desktop client application and an ASP.NET Web REST API to support the client. The application is used to monitor, record, and control manufacturing equipment and store issues within them for maintenance use.
  • Managed a small team of developers and testers; also worked with application requirements using GitHub tasks.
  • Launched the application using a private Windows store for five office locations.
Technologies: Visual Studio, Universal Windows Platform (UWP), UI Design, ASP.NET Web API, Microsoft SQL Server, Azure, C#, Git, GitHub, APIs, Technical Leadership

Back-end Developer

2010 - 2014
  • Developed an ASP.NET and WinForms combination application for a steel manufacturing plant.
  • Implemented optimization logic for source material management.
  • Designed an SQL Server database to support about 10 million rows for storing and reporting plant data.
Technologies: Visual Studio, C#, ASP.NET, Windows Forms (WinForms), Entity Framework, Microsoft SQL Server, Web API

Back-end Developer

2008 - 2011
  • Developed real-time advertising solutions to select and run ads on a television channel. The ad data was stored on an SQL Server database, and retrieved using stored procedures.
  • Integrated the solution to a television control system using TCP/IP.
  • Managed requirements using Jira and set up a version control system using Microsoft Team Foundation Server (TFS).
Technologies: Visual Studio, C#, Microsoft SQL Server, Stored Procedure

Lead Developer

2005 - 2008
  • Developed a Windows desktop application for managing airplane and helicopter snags, warehouse and inventory management, and preventive maintenance.
  • Managed project requirements and issues with Atlassian Jira.
  • Migrated existing snag data from Microsoft Access database to SQL Server.
Technologies: Visual Studio, C#, Windows Forms (WinForms), Microsoft SQL Server

Lead Developer

2002 - 2005
  • Developed a product management system and a webshop for a retail company using newly-released C# and ASP.NET. The solution consisted of a desktop product management application and a webshop with ASP.NET.
  • Implemented CSV and XML pricing information import and export functionality.
  • Set up the production environment using Windows Server 2000 and IIS.
  • Created a monitoring system for the webshop that checks to see if it's online and working correctly.
Technologies: Visual Studio, C#, ASP.NET, Microsoft SQL Server, IIS

Lead Developer

1998 - 2002
  • Developed an integration application using XML and simple object access protocol (SOAP); also designed the integration architecture and managed a small team of developers.
  • Built a simple monitoring user interface for the solution to quickly find integration errors and asses performance.
  • Wrote a Finnish book about XML/SOAP integrations based on my experience in this project and others.
Technologies: Delphi, Microsoft SQL Server, XML, SOAP

Lead Developer

1996 - 1998
  • Developed a Windows desktop accounting app for small businesses and home users; my work included architecting the app, creating the UI and the accounting logic, and designed the SQL database to support the data.
  • Composed simple marketing material for the application and coded an installer utility for the application; also created the release build and helped to press 20,000 copies of CDs for the application.
  • Helped to support the application and develop patch releases and continued development until 1998, when the development was handed over to an in-house developer.
Technologies: C++, Delphi, Microsoft SQL Server

Public Web API for a Real-time Video Management System

I built an ASP.NET and C#-based real-time video management system using SQL Server as the database. I also designed both the architecture and a public Web API and implemented the first version.

The application is available in 40 countries.
1996 - 2000

Associate Degree in Computer Science

University of Helsinki - Helsinki, Finland


Certified Microsoft Technical Specialist



Web API, Entity Framework, LINQ, NServiceBus, REST APIs, Windows Forms (WinForms)


Visual Studio, Jira, Git, GitHub, RabbitMQ


ASP.NET MVC, .NET Core, .NET 5, ASP.NET Web API, ASP.NET, .NET, OAuth 2, Blazor


C#, C#.NET, XML, SQL, JavaScript, CSS, HTML, XSD, Delphi, Stored Procedure, Visual Basic .NET (VB.NET), C++


Unit Testing, Design Patterns, UI Design, DevOps


Azure SQL Databases, Data Integration, Azure SQL, Microsoft SQL Server


Windows, Azure, Universal Windows Platform (UWP), Telerik, Windows UI


Software Development, System Integration Testing (SIT), Architecture, Microsoft Stack, XML Web Services, Integration, SOAP, IIS, Monday.com, Technical Leadership, APIs, Electronic Data Interchange (EDI)

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