Ken is available for hire
Hire KenKen Lange
Verified Expert in Engineering
Full-stack Developer
Waterford, CT, United States
Toptal member since September 30, 2022
Bio
Ken is a full-stack developer specializing in C#.NET. He has been developing software professionally for over 20 years, both as an employee and freelance. Proficient in several technologies, programming languages, and frameworks, Ken brings a comprehensive skill set and a great deal of experience in solving software problems.
Portfolio
Greenwald Industries
C#, C, C++, TypeScript, HTML, .NET, .NET Core, ASP.NET MVC, Entity Framework...
Sealed Air
C#.NET WinForms, ASP.NET Web API, Angular, SQL, C#.NET, Oracle, IBM Db2...
National Kiko Registry
C#.NET, Blazor, MySQL, Entity Framework Core, Azure, Azure Storage, Quest PDF
Experience
- C#.NET - 18 years
- ASP.NET Web API - 10 years
- Azure Table Storage - 10 years
- Azure Service Bus - 10 years
- Angular - 6 years
- Azure Functions - 5 years
- Entity Framework Core - 5 years
- Blazor - 3 years
Availability
Part-time
Preferred Environment
.NET, C#, ASP.NET Web API, Blazor, Windows Forms (WinForms)
The most amazing...
...project I've worked on is a production and inventory control system that has been orchestrating a Fortune 500 chemical blending operation for 20+ years.
Work Experience
Freelance Software Developer
2011 - PRESENT
Greenwald Industries
- Integrated third-party credit card payment APIs, including PayPal, FreedomPay, Elavon, and Global Payments.
- Built a C# codebase to interact with smart card products via Windows PC/SC API that uses cryptographic protocols for Mifare DESFire, Atmel CryptoMemory, and Inside Contactless PicoPass cards.
- Created Microsoft Azure-hosted services using Azure Functions, Azure Service Bus, Azure Table and Blob Storage, and Azure Cosmos DB.
- Built Angular UI components to dynamically generate settings pages for a catalog of laundry machine models, each with a unique and complex set of interactive settings.
Technologies: C#, C, C++, TypeScript, HTML, .NET, .NET Core, ASP.NET MVC, Entity Framework, Entity Framework Core, ASP.NET Web API, Azure, Azure SQL, Azure Table Storage, Azure Cosmos DB, Azure Service Bus, Azure App Service, Angular, Azure Functions, Azure WebJobs, ASP.NET Core, CSS, JavaScript, Bootstrap, Windows Presentation Foundation (WPF), Microsoft SQL Server, Bluetooth, Bluetooth Low Energy (LE), Visual Studio 2019, Windows Forms (WinForms), Deployment, ASP.NET, Windows, REST APIs, Microsoft Visual Studio, Encryption, Card Payments, API Integration, Web API, Visual Studio, .NET 4, Model View Controller (MVC), SQL Server 2016, APIs, Microsoft Visual C++, Integration, Databases, MySQL, .NET 6, Web Architecture, Continuous Integration (CI), DevOps, Architecture, Azure DevOps, Microsoft Web, Embedded C, Front-end Development, Web Development
Freelance Software Developer
2011 - PRESENT
Sealed Air
- Developed a full-stack production and inventory control system for chemical blending processes. The system enables operators to devise, plan, and execute chemical blending operations while tracking inventory.
- Ported a legacy system from Win Forms/DB2 architecture to Angular, ASP.NET Web API, and Oracle architecture.
- Developed a custom reporting engine to replace legacy Crystal Reports and MS Report Viewer components. Reports are compiled from data in Oracle database and rendered directly as PDF or CSV format on demand.
Technologies: C#.NET WinForms, ASP.NET Web API, Angular, SQL, C#.NET, Oracle, IBM Db2, Crystal Reports, Microsoft Report Viewer, Git, ADO.NET, ASP.NET Core, CSS, JavaScript, Bootstrap, VB.NET WinForms, Visual Studio 2019, Windows Forms (WinForms), Visual Basic, Deployment, ODBC, ASP.NET, Windows, REST APIs, Microsoft Visual Studio, API Integration, Web API, Visual Studio, .NET 4, Model View Controller (MVC), APIs, Integration, Databases, Visual Basic 6 (VB6), Visual Basic .NET (VB.NET), Web Architecture, Architecture, Microsoft Web, GitLab, Front-end Development, Web Development
Web Application Developer
2023 - 2024
National Kiko Registry
- Developed a web application to manage registry and pedigree-tracking services for breeders of Kiko Goats.
- Identified system requirements by analyzing the legacy system's Visual Basic source code and SQL database and interviewing and observing registry workers.
- Built a reporting engine to generate custom PDF formatted registration certificates with varying graphical elements based on pedigree characteristics and tabular reports of herd details.
- Integrated document image scanning feature directly into browser-based web application using a custom URL scheme.
Technologies: C#.NET, Blazor, MySQL, Entity Framework Core, Azure, Azure Storage, Quest PDF
Web Application Developer
2023 - 2024
e-Zinc Inc.
- Developed a web application to monitor, collect, and analyze multi-channel time series data streamed from battery testing equipment.
- Worked with battery testing engineers to identify requirements, resolve performance issues, and improve usability.
- Designed a back-end data processing pipeline using Azure Functions, queues, and BLOBs to handle high volumes of streaming data.
- Built a reporting engine to allow users to compile custom reports from dozens of calculated battery testing metrics and data channels.
Technologies: C#.NET, Blazor, Azure, Azure Functions, Azure Storage, OpenXML, ASP.NET Core, Azure Active Directory, InfluxDB, Microsoft SQL Server, Entity Framework Core
Freelance Software Developer
2011 - 2022
WEI Inc.
- Programmed Allen-Bradley PLCs in Ladder Logic for manufacturing automation applications. Integrated with Panel View UI devices.
- Programmed Universal Robots UR5 and UR10 robots in Python for various manufacturing automation applications. Developed machine vision programs to locate parts to be picked by the robot and placed onto tooling.
- Developed a WinForms application with .NET Core for control of an automated defect scanning system. The application orchestrates motion control of the scanning bed and stitches 3D data from eight laser scanning heads into a composite image.
Technologies: .NET, .NET Core, C#, Python, Robotics, Allen-Bradley PLCs, C#.NET WinForms, Git, ADO.NET, Entity Framework, Entity Framework Core, SQL, CSS, Windows Presentation Foundation (WPF), Microsoft SQL Server, Visual Studio 2019, Windows Forms (WinForms), Deployment, ODBC, ASP.NET, Windows, REST APIs, Microsoft Visual Studio, Encryption, API Integration, Web API, Visual Studio, .NET 4, Model View Controller (MVC), SQL Server 2016, APIs, Biometrics, Integration, Databases, .NET 6, Web Architecture, Architecture, GitLab, Front-end Development, Web Development
Software Developer
2008 - 2011
Greenwald Industries
- Built web applications and services for the management of laundry vending systems.
- Developed cryptographic methods to secure laundry vending operations, communications, and data persistence.
- Created firmware for an embedded microprocessor to interact with contactless Smart Card using the ISO 14443 RF protocol.
Technologies: Cryptography, SQL, HTTP, C#, .NET, LINQ, LINQ to SQL, Crystal Reports, C++, C, Windows Communication Foundation (WCF), ASP.NET Web Forms, Microsoft Foundation Classes (MFC), Microsoft Foundation Class (MFC) Library, Microsoft Report Viewer, CSS, JavaScript, Windows Presentation Foundation (WPF), Microsoft SQL Server, Bluetooth, Windows Forms (WinForms), Deployment, ASP.NET, Windows, REST APIs, Microsoft Visual Studio, Encryption, Card Payments, API Integration, Web API, Visual Studio, .NET 4, Model View Controller (MVC), APIs, Twilio API, Microsoft Visual C++, Integration, Databases, MySQL, Web Architecture, Continuous Integration (CI), DevOps, Architecture, Microsoft Web, Embedded C, Front-end Development, Web Development
System Integration Engineer
1997 - 2008
WEI Inc.
- Built a driver's license production desktop workstation that performs biometric image and fingerprint capture, document scanning, and secure credential card printing.
- Developed distributed back-end systems to coordinate the driver's license production workflow and archive the captured data across locations.
- Integrated system components in manufacturing automation projects, including motion control, machine vision, and PLC and PanelView programming.
Technologies: C#.NET WinForms, Allen-Bradley PLCs, C#.NET, Cryptography, .NET, C#, ADO.NET, Windows Communication Foundation (WCF), Microsoft Foundation Class (MFC) Library, Microsoft Foundation Classes (MFC), SQL, Windows Forms (WinForms), Microsoft SQL Server, VB.NET WinForms, Visual Basic, Deployment, ODBC, ASP.NET, Windows, Microsoft Visual Studio, Encryption, API Integration, Visual Studio, .NET 4, APIs, Microsoft Visual C++, Biometrics, Integration, Databases, Visual Basic 6 (VB6), Visual Basic .NET (VB.NET), Architecture, Embedded C
Acoustic Engineer
1996 - 1997
General Dynamics Electric Boat
- Analyzed the acoustic response of submarine structures using Finite Element Analysis (FEA) and Statistical Energy Analysis (SEA).
- Developed C++ programs for management and manipulation of FEA and SEA data.
- Performed analysis and debugging of Ada-based sonar simulation.
Technologies: C++, Unix, Finite Element Analysis (FEA), Ada
Experience
Scalable Distributed Messaging System for Remote Laundry Vending Devices
Designed and implemented a highly scalable messaging system that provides reliable communication with laundry vending devices. The system has been in continuous service for eight years and provides real-time connectivity to thousands of devices at remote locations. It is built around Azure Service Bus Topics and Serverless Azure Functions. The system allows the customer's back-end software to configure, vend, and collect data from laundry devices at remote locations.
Purchase Code Generation Web Service for Smart Card Laundry Vending
Designed a cryptographic algorithm to encode a purchased value for laundry vending as a short PIN code that can be entered into an offline device at the vending location to be redeemed. In addition, I implemented a web service to provide secure code generation on demand to third-party payment applications.
The system has been operating for ten years and handles millions of dollars per year of laundry vending transactions. While the system was initially implemented as a Windows Communication Foundation web service, I have since updated it to an ASP.NET Web API service. The novel code scheme prevents random guessing of codes while allowing codes to be redeemed only once across multiple disconnected devices. This property sets it apart from competitors' products, which require connected devices for redemption.
The system has been operating for ten years and handles millions of dollars per year of laundry vending transactions. While the system was initially implemented as a Windows Communication Foundation web service, I have since updated it to an ASP.NET Web API service. The novel code scheme prevents random guessing of codes while allowing codes to be redeemed only once across multiple disconnected devices. This property sets it apart from competitors' products, which require connected devices for redemption.
Production and Inventory Control System for Chemical Blending Manufacturer
Worked as the primary developer on this system that orchestrates chemical blending operations for a fortune 500 manufacturer. After working on the system for 15 years, I was contracted to port it to its current architecture as a cloud-hosted ASP.NET Web API service fronted by an Angular SPA-style user interface. Chemical engineers use the system's UI to design blending recipes that detail how raw materials will be combined and blended to create various chemical products. The system then orchestrates pumping and mixing equipment to carry out the production batches while tracking lot codes and amounts for all materials used. A report generation sub-system provides dozens of printable reports and queries to cover all aspects of the manufacturer's inventory, production, receiving, and filling operations.
Education
1994 - 1996
Master's Degree in Mechanical Engineering
Rutgers University - New Brunswick, New Jersey, USA
1990 - 1994
Bachelor's Degree in Mechanical Engineering
Rutgers University - New Brunswick, New Jersey, USA
Skills
Libraries/APIs
LINQ, Windows Forms (WinForms), REST APIs, Web API, Microsoft Foundation Class (MFC) Library, Entity Framework, ODBC, Microsoft Foundation Classes (MFC), Twilio API
Tools
LINQ to SQL, C#.NET WinForms, Azure App Service, Visual Studio 2019, Microsoft Visual Studio, Visual Studio, Git, Crystal Reports, Microsoft Report Viewer, Microsoft Visual C++, GitLab
Languages
C#.NET, C#, SQL, C++, JavaScript, TypeScript, C, Python, HTML, Visual Basic, Visual Basic 6 (VB6), Visual Basic .NET (VB.NET), Embedded C, Ada, CSS
Frameworks
.NET, .NET Core, ASP.NET Core, ASP.NET, .NET 4, ASP.NET Web API, Blazor, Entity Framework Core, ASP.NET Web Forms, ASP.NET MVC, Angular, ADO.NET, Bootstrap, Windows Presentation Foundation (WPF), VB.NET WinForms
Paradigms
Model View Controller (MVC), Web Architecture, Continuous Integration (CI), DevOps, Azure DevOps
Platforms
Azure, Windows, Oracle, Azure Functions, Unix, Bluetooth Low Energy (LE)
Storage
Azure Table Storage, Databases, Azure Cloud Services, IBM Db2, Azure SQL, Microsoft SQL Server, SQL Server 2016, MySQL, Azure Cosmos DB, Azure Storage, OpenXML, Azure Active Directory, InfluxDB
Other
Azure Service Bus, Encryption, Card Payments, API Integration, APIs, Integration, Software Development, .NET 6, Architecture, Microsoft Web, Front-end Development, Web Development, HTTP, Cryptography, Windows Communication Foundation (WCF), Robotics, Allen-Bradley PLCs, Azure WebJobs, Bluetooth, Deployment, Biometrics, Finite Element Analysis (FEA), Quest PDF
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