Features and limitations

The editor is Stable under the stability policy. It is not Microsoft Excel parity: content the model does not cover is kept through a save or reported, as described in the preservation guarantee. This page lists what the editor is built to handle and what it does not; when a workbook contains something unsupported, the editor reports it (workbook-warning) instead of hiding it.

The current parity status and evidence summarize implemented work, native Excel comparisons and the remaining gaps. What survives an edit and a save, and what is dropped or reported, is in Supported features and preservation guarantee.

Test coverage

The browser tests (e2e/xlsx/*.spec.ts) cover opening .xlsx, .xls and .csv, typing values and formulas, recalculation, ribbon formatting, row insertion and deletion, sheet tabs, undo and redo, Find and Replace, Format Cells, chart selection, save and reopen, read-only mode, locales and all six framework bindings. The workbook writer, pivots, slicers, sparklines and print formatting are also checked by opening saved files in Excel 16 (native acceptance). Everything else below is covered by unit tests.

File formats

Format	Open	Save	Notes
.xlsx, .xltx	yes	yes	The main format.
.xlsm	yes	yes	The VBA project is carried through unchanged; macros never run.
.xls (97-2003)	yes	as .xlsx	Read through the shared ole2 codecs: values, formulas where they decode, basic formatting, merges, column widths, row heights, frozen panes.
.csv	yes	yes	RFC 4180, delimiter auto-detected; fields beginning with = stay text on import. Export writes the active sheet's displayed values and protects against formula injection.
Password-protected	yes	yes	Encrypted .xlsx/.xlsm files prompt for a password. File > Info > Encrypt Workbook sets a password for subsequent Excel saves. Opening an encrypted file does not retain its password for saving; set it again before saving.
.xlsb, .ods	no	no

Grid and formatting

• Cell values, shared strings with rich text runs, booleans, errors and dates (1900 and 1904 date systems).
• Fonts, fills (solid, pattern, gradient approximated), borders, alignment, wrap, indent, rotation.
• Number formats: sections, conditions, colours, dates and times, fractions, scientific, text. A General number that does not fit its column drops decimals or switches to scientific notation, and other numbers show ###, measured with the browser's fonts.
• Row heights follow wrapped or enlarged text after an edit unless the row has a custom height.
• Merged cells, column widths and row heights, hidden rows and columns, frozen panes, zoom, gridlines.
• Conditional formatting: cell rules, text rules, "A Date Occurring" (today, last 7 days, this month, ...), top and bottom, above average, duplicates, colour scales, data bars, icon sets, with a Rules Manager that edits, reorders and deletes rules.
• Data validation, with the list drop-down offered in the grid.
• Comments and threaded replies (shown, edited, resolved and reopened with undo), hyperlinks. Imported @mentions are preserved; creating new @mentions is not supported.

Formulas

The calculation engine lives in ooxml-core and recalculates dependents after each edit. Its catalogue holds 502 functions (see the generated list) across math and trigonometry, statistics (including the inverse distributions and the LINEST, LOGEST, TREND and GROWTH family), logic, text (including REGEXTEST, REGEXEXTRACT and REGEXREPLACE), dates, lookup (including XLOOKUP and dynamic arrays such as FILTER, SORT, UNIQUE and SEQUENCE), information, financial (including the bond, coupon, odd-period (ODDFPRICE, ODDFYIELD, ODDLPRICE, ODDLYIELD), discount-security and Treasury bill functions, AMORDEGRC, VDB and XIRR), engineering (including COMPLEX, the IM functions, CONVERT and the BESSEL functions) and database (DSUM, DCOUNT, DGET and the rest). Insert Function lists them by category. The supported function list is generated from the registry and marks which functions have Excel-recorded test values.

Not every Excel function exists: an unknown one shows #NAME?. These are not implemented: ASC, DBCS, JIS, PHONETIC, INFO and WEBSERVICE. GETPIVOTDATA reads the pivots of this editor (worksheet-range pivots) from their cached records and returns #REF! for anything it cannot resolve. GROUPBY and PIVOTBY are a subset: one aggregating function (a function name such as SUM or PERCENTOF, or a LAMBDA), grand totals only (total depth 0, 1 or -1, no subtotals), field headers 0, 1 or 3, no function arrays, and flat group output with the row labels repeated; PIVOTBY takes one column field. TRIMRANGE returns the trimmed values as an array rather than a reference. BESSELJ(1.9,2) returns the exact 0.3299257277, which differs from the 0.329925829 Microsoft documents (Excel itself is about 1e-7 off there). The odd-period security functions use the quasi-coupon method and reproduce Microsoft's examples; long odd first periods are not checked against Excel. External workbook references are kept but not resolved.

Circular references are reported and left at 0 unless iterative calculation is on. Turn it on in File > Options > Formulas (Enable iterative calculation, with Maximum iterations and Maximum change); the setting is saved with the workbook (calcPr iterate, iterateCount, iterateDelta). A circular group is then recalculated up to the maximum iterations and stops once no cell changes by more than the maximum change. Turning it on or off is not an undo step.

Calculation can be switched between Automatic and Manual (Formulas > Calculation Options, or File > Options); the mode is saved with the workbook. Calculate Now (F9) and Calculate Sheet (Shift+F9) recalculate on demand. Show Formulas (Ctrl+`) displays formula text instead of results.

Editing

Typing into cells (values and formulas), the formula bar and name box, Ctrl+; and Ctrl+Shift+; for the current date and time, fill, copy and paste (with the system clipboard as text and HTML; several areas copy when they share rows or columns, as in Excel), insert and delete rows, columns and cells, sorting, filtering, remove duplicates, find and replace, sheet management (add, rename, move, hide, colour; new sheets are named in the interface language, for example Tabelle2 in German), the built-in cell styles, tables (style options, header and total rows, resize, convert to range), row and column outline groups, page setup and print options (gridlines, headings, centring), undo and redo with meaningful step names. Formula references follow structural edits.

What-If Analysis (Data > Forecast > What-If Analysis) has three tools. Goal Seek changes one input cell until a formula cell reaches a value, iterating the recalculation engine (up to the workbook's Maximum iterations, default 100, until within Maximum change, default 0.001); the Goal Seek Status dialog keeps the result with OK and restores it with Cancel, and the whole run is one undo step. Data Table turns a selection into a one- or two-variable {=TABLE(row input, column input)} table: the results are recomputed by substituting the header values into the input cells (the real inputs are never changed) after every calculation, the table is read and saved as <f t="dataTable"> and editing part of it is refused ("Cannot change part of a data table."; selecting the whole table and clearing it removes it). Scenario Manager adds, edits, deletes and shows scenarios (up to 32 changing cells each, with comment and protection flags) saved as the sheet's <scenarios> element. Forecast Sheet (Data > Forecast) opens a dialog with the timeline and values ranges, the forecast end, the confidence interval, seasonality (automatic or manual), how to fill missing points and aggregate duplicates, optional statistics and a line or column chart, and builds the forecast on a new sheet with FORECAST.ETS and FORECAST.ETS.CONFINT formulas; its numbers carry the differences from Excel listed in functions.md. Scenarios and data tables follow row and column inserts and deletes. Scenario Manager's Summary builds the standard "Scenario Summary" sheet (values only, laid out and styled as Excel 16 writes it, with the changing cells of every scenario and the result cells you name) before the scenarios' sheet, and Merge appends the scenarios of another sheet of the workbook (a taken name becomes <name> <yyyy-mm-dd>, as in Excel). Not implemented: the Scenario PivotTable report, merging from other workbooks, Goal Seek's Step and Pause, and data tables on sheets other than the input cells' own.

Sheet and workbook-structure protection can carry a password. It stops accidental edits; it is not security. The editor reads and checks both Excel's legacy 16-bit hash and its newer SHA-512 (also SHA-1, SHA-256 and SHA-384) hash, so Unprotect Sheet and Unprotect Workbook ask for the password whichever hash the file carries. A password set in the editor is written as the legacy hash. A protection whose hash uses a digest the core cannot compute is never unlocked by a password.

Pictures and charts are selected by clicking them: they move and resize with the mouse, nudge with the arrow keys and are removed with Delete; a selected chart shows the Chart Design tab.

Charts and SmartArt

Common chart families (column, bar, line, area, pie, doughnut, scatter, bubble, stock (high-low-close and open-high-low-close) and radar), bar/line combinations with a secondary axis, and waterfall, histogram, treemap and sunburst charts (from their ChartEx parts) render as SVG from live values. Volume-stock combinations and surface charts show a labelled frame.

Insert > Chart opens the shared chart picker, the same one Word and PowerPoint use. Every chart is edited over its parsed chart model (ChartSpace, the shared model in ooxml-core/chart):

• Chart Design tab: Chart Styles, Change Colors and Chart Layouts (Quick Layout 1 to 11 for column, bar, line and area charts) galleries, Chart Title and Legend, Type, Series Options, and Delete. The galleries are the shared ones, so they look the same in every product.
• Format pane: a docked panel with the shared chart Format pane. It edits the border and outline of the chart, axes (bounds, units, scale, crossing, tick marks, labels, number format), gridlines, data labels, the legend and series options. Supported controls also cover effects, shape 3D, text, pattern fills, markers, trendlines/error bars, axis titles and admitted secondary axes. Series and chart-area fills open the same panel from their Series Options commands.
• A type change keeps the formatting: titles, legend, axes and fills carry over to the new type.
• A chart part whose content the model cannot carry (for example detail below the top level, such as an unknown nested series extension) is never rewritten from the model. Its chart commands and Format pane are disabled, a workbook warning reports it, and it is saved from its source bytes, with only moved references patched in.

Picture media allocation remains host-owned. Secondary-axis authoring keeps the first series as its primary rendering anchor; horizontal combinations, stacked multi-series splits and unknown extension splits are refused. Multiple trendlines are preserved but not offered by the one-line editor, and custom error ranges have no range editor. Chart styles are curated recolour presets, so native style definitions (styleN.xml) cannot be authored. Surface charts are not drawn. Imported supported shadows/gradients, axis visibility, inherited fonts, rich title runs and manual layouts have rendering/preservation support. Exact text measurement, placement, effects and raster fidelity remain incomplete.

ChartEx has shared data-sheet, family-option, axis and point-label controls for admitted local workbooks, including structural edits and safe workbook growth. Its shared Format pane supports pattern fills, effects, text and shape 3D formatting. Unsupported external data and ambiguous hierarchy sources are refused; classic-only series and secondary-axis controls are hidden. Twelve Word/Excel browser cases cover six bindings, and native Office 16 checks cover selected ChartData and save/reopen paths. These are bounded acceptance checks, not native layout parity; see the delivery ledger.

Insert > SmartArt opens the shared layout picker (35 layouts). The SmartArt Design tab and text pane support node/text/layout editing, history, Styles and Change Colors. The shared catalogue has three style intensities and five theme-accent colour schemes. Word and Excel use the neutral layout interpreter and richer painter for uncached, inserted and edited diagrams, with explicit partial or approximate fallback. Admitted interpreted 2D layouts gain generated drawing caches on save; complex 3D, folding and unsupported text remain uncached. Node overrides, rich text and unknown XML are preserved. The wider native style catalogue, dedicated per-node formatting and rich text authoring in Excel's text pane remain incomplete. Native Word/Excel style/colour checks verify semantic text, ids and nonempty node shapes, not pixel-identical Office layout.

Sparklines

Excel 2010 sparklines are drawn in their host cells, behind the cell's text: line (with markers and high, low, first, last and negative points), column and win/loss. The drawing follows the group's settings for empty cells (gap, zero or connected), the vertical axis (each sparkline, the whole group or custom limits), the horizontal axis at zero, the date axis, right-to-left plotting, hidden cells and theme or RGB colours. A sparkline repaints when a cell in its data range changes and resizes with its cell. The sparkline XML is saved exactly as loaded, and inserted or deleted rows and columns move it with its cells.

Insert > Sparklines creates line, column and win/loss groups from a data range and a location range. A vertical location range maps data rows to individual sparklines; a horizontal location range maps data columns. Select a host cell and choose Sparkline Settings to change the entire group's type, markers, series and negative colors, line weight, empty and hidden cell handling, axis visibility, direction and individual, shared or custom vertical limits. Clear Selected Sparklines removes the selected hosts; Clear Sparkline Groups removes their entire groups. These changes support undo and save/load.

Style galleries are not available. The date axis can be switched on and off in Sparkline Settings. Exact Excel pixel output (marker size, column gap and line anti-aliasing) is not matched, and non-numeric cells in a data range are treated as empty.

Not supported (preserved where possible)

Feature	Behaviour
Pivot tables and pivot caches	Worksheet-range PivotTables (any number of row and column fields, a report filter and up to 16 value fields, with per-field custom subtotals) are created, shown, refreshed and saved. A numeric row or column field can be grouped by number ranges (Group Field, Ungroup) and a date field by seconds up to years (Group Dates); hidden items and a timeline date range filter the report. Other pivots (external or OLAP sources, calculated fields, label or value filters, shared caches) are kept on save but not shown or refreshed.
Slicers, timelines	Table and PivotTable slicers are drawn (caption header, Multi-Select and Clear Filter buttons, item buttons in columns with selected, unselected and no-data states, the 14 built-in styles) and filter the table or PivotTable on click, Ctrl, Shift and Multi-Select. Insert > Slicer and Insert > Timeline add them; the Slicer and Timeline tabs set caption, style, columns, size, sort order and time level. Timelines on a PivotTable date field show years, quarters, months or days and filter by click, Shift+click or drag. Slicers on OLAP or other unsupported sources, and slicers connected to several PivotTables, are kept on save but drawn as placeholders. Style colours follow Excel's styles but are not measured from a native render.
Sparkline authoring	Creation, group settings and clearing are supported (see above); grouping and ungrouping (Insert > Sparklines) merge the touched groups into the first one or split each into single-sparkline groups; the style gallery is not implemented.
Advanced charts and chart options	Common families and supported formatting are described above. Advanced families, complete axes/labels/effects authoring and exact native layout remain incomplete.
Shapes, SmartArt, form controls	Pictures display. SmartArt uses cached or interpreted drawing with an explicit fallback; nodes, text, layout, shared Styles and Change Colors are editable. Admitted 2D caches are generated; wider native styles, rich-text authoring and complex 3D remain limited. Shapes, text boxes, connectors and groups are drawn from the shared preset geometry with their fill, outline, style colours and text (approximate text wrapping; no effects, 3D or pattern fills); they can be selected, moved and resized. Form controls are drawn with a static Windows appearance from their linked cell and list range; check boxes, option buttons, drop-downs, list boxes, spin buttons and scroll bars write the linked cell (one undo step each; a scroll-bar drag writes per move), and the cached state in the control part follows the cell on save. Controls are not moved or resized in the editor, and buttons do not run their macro. Ink and OLE objects show as placeholders. All of them round-trip verbatim.
Macros (VBA), add-ins, Power Query	Never executed; the VBA project is carried through.
External links and data connections	Kept; values are the cached ones.
Real-time collaboration	Cell values, formulas, formats, sheets, row and column sizes, merges and names are shared over ooxml-core/collab (File > Share or the collaboration property); remote selections show in the grid and undo is per person. Notes and replies, hyperlinks, conditional formats, validation, tables and charts are shared per item; images, other drawings and page setup stay local; the host owns the server and saving. See collaboration.
Printing	The browser's print of the used range or print area. Page Layout view (pages, rulers, editable header and footer bands with &P &N &D &T &F &A codes, cell editing; no copy and paste in it) and Page Break Preview (print-area shading, page numbers, dashed automatic and solid manual break lines, drag a break or the print-area edge, with undo) are chosen from the status bar or View > Workbook Views and saved per sheet (sheetView/@view). Breaks cannot be dragged while Fit to pages is on. View > Custom Views lists, shows, adds and deletes views: each records the sheets' zoom, grid lines, headings, panes and selection, and optionally hidden rows and columns, the filter and the print settings (see the parity status for what is not captured).
Document properties	Core, company, manager and custom properties are editable in File > Info with undo. Unknown custom-property types are kept and displayed read-only.

The core's round-trip tests and Excel acceptance checks live in the ooxml repository. Report a workbook that renders or saves wrongly as an issue with the file attached if you can share it.

Digital signatures are reported when opening a workbook and removed on save. The editor does not sign files. Hyperlinks follow the shared core policy; only web and e-mail links open externally.