ReoGrid V4 for .NET — Released! High-Speed Data Processing and Stronger Excel Compatibility

UNVELL Inc. has released ReoGrid V4, the latest version of its spreadsheet component for .NET applications.

ReoGrid is an Excel-like spreadsheet component for .NET. Since its launch in 2014, it has been adopted in many enterprise systems and R&D projects in Japan and abroad. It supports both Windows Forms and WPF, and integrates easily with a single DLL. It is widely supported by developers as a library that combines a natural, Excel-like feel with fast, lightweight performance.

The new Lazy Loading feature enables smooth initialization and rendering even for datasets in the millions of rows.

Loading 100,000 rows of data, for example, took roughly 6–10 seconds in the previous V3, while V4 completes it in just a few hundred milliseconds. Even one million rows can be initialized in under a second.

With Lazy Loading, only the cells in the visible range (about 30 rows) are loaded and rendered first. Cells are then loaded progressively as needed in response to scrolling, zooming, and formula calculation. This design handles huge datasets flexibly while drastically reducing memory usage, delivering an efficient, comfortable application experience.

Multi-row headers and merged cells are now supported, allowing for more flexible, more readable table layouts. This makes it easier to design complex header structures with main and sub-categories, as well as a wide variety of report and summary screens.

Other improvements include major feature additions to the WPF edition, outline support, search, conditional styles, an enhanced data source mechanism, Excel-compatible custom number formats, expanded function coverage, automatic correction of floating-point arithmetic errors, official support for automated UI testing via WinAppDriver, and faster rendering performance through a redesigned rendering engine.

ReoGrid V4 has shifted from the previous open-source, free distribution (MIT License) to a commercial license model. Multiple editions (Professional and Enterprise) are available based on project size and support needs, with continuous post-purchase support.

The previous free version, ReoGrid V3 (MIT License), remains available free of charge. It can still be used for prototyping, evaluation, and adoption with minimal initial cost.

ReoGrid V4 also offers paid support services for adoption assistance and development consulting. Engagements can range from technical advice during requirements definition to long-term operational design and custom development of ReoGrid itself.

We anticipate adoption in a wide range of fields, including finance, public transit, automotive, manufacturing, and universities and research institutions in Japan and abroad — for business-form systems, data-analysis tools, government systems, and engineering computation support.