Demos

Each demo runs the real engine in your browser; nothing is sent to a server. Each link opens the page that hosts the demo, next to the explanation it illustrates.

Formulas and recalculation

• Evaluate a formula: type a formula and see the engine's result, its value kind, and how errors such as #DIV/0! come back as values.
• Recalculate a workbook: load an .xlsx or generate a sample, recalculate it, and download the saved bytes. The same demo appears in Browser workbook upload.
• Dependency tracing: select a cell in a formula chain and see its precedents and dependents, with a depth control.
• Iterative calculation: solve a circular reference and watch the residual curve change as you adjust the tolerance.

Workbook features

• Data-validation checks: test a proposed number without writing it, then see that a direct engine write can store a value outside the rule.
• Dynamic arrays: preview the spill shape of an array formula, commit it to a sheet, and trigger a #SPILL! case.
• PivotTables: configure a pivot table and inspect the cells the engine projects.
• Inserting and deleting rows and columns: edit the structure and compare formulas before and after, including references that collapse to #REF!.
• XLSX and XLSB round trip: write one workbook into both containers and read each back.

Compatibility

• How far compatibility goes: run floating-point, date, coercion, locale and spill edge cases and compare each result with the value captured from Excel.
• Function lookup: search the function catalog read from the running engine, with arity and implementation status.
• Error model: compare a formula error value with a host failure from loading invalid bytes.

formulon-cell UI

• Charts: select the sample data, insert a chart, and explore its series and settings in the full spreadsheet demo.
• Dynamic language switching: try seven UI languages on the same workbook, comparing the calculation profile, localized formula, stored formula and results.
• Full spreadsheet demo: edit a seeded workbook, open menus and dialogs, switch themes and platform UI, and change which controls are visible.
• Read-only report viewer: a fixed viewport that allows only selection and copy.
• Fixed-input form: a sheet where only designated cells accept input.
• UI profiles: switch chrome and density with setUi() without remounting.
• Host updates and events: push values from the host and watch the events the sheet emits.
• Theme and locale switching: change theme and UI dictionary on a mounted sheet.
• Overlays inside a native dialog: keep the sheet and its floating UI inside one dialog boundary.