Merge & Clean Spreadsheet Files

Process files locally in your browser. Workbook mode retains separate worksheets, ordinary cell types, number formats, source styles and colors, safe local formulas and names, tables, notes, validation, links, embedded pictures and supported charts. Supported calendar lookups, named and structured ranges, whole-column and computed date-text criteria, mixed numeric/calendar criteria and conditional rules retain their source meaning across supported date-system combinations. Signed and formula-only negative 1904 date/time cases retain their source epoch with independently bounded modern-date conversion. Coherent local pivot cleanup supports ordinary SUM plus COUNT multi-measure Values columns, standard aggregates, normal hidden-member/page filters, discrete and monthly grouping, arithmetic calculated fields, supported row hierarchies and a row-by-column grid; initial saved summaries and Refresh are independently checked. Independently proven same-row arithmetic formula sources are supported. Source-theme image fills, partial chart themes, custom chart color maps, grouped shapes, editable SVG icons with PNG fallback and local A1-linked shape text retain their graph and references. CSV mode combines selected table data and preserves signed numeric fields while protecting formula-triggered text.

• 2–20 inputs, 5 MiB each and 20 MiB combined, with 50,000 rows, 500 columns and 500,000 cells. Selected headers must be unique and nonempty. XLSX retains sheets; union-header alignment applies to CSV mode. Each local worker operation stops after60 seconds.
• Workbook preservation remains qualified to supported features. Unsafe transformations stop before a changed output is offered. When mixed date systems require converting an ambiguous slash-date criterion, choose Day / month / year or Month / day / year explicitly; the default asks for a choice. Literal text and criteria needing no date-system conversion remain literal. Calendar cells with conditional number formats exposing raw serials retain their constrained source epoch while independently bounded companion dates convert. A fictional 1900 leap-day serial combined with signed negative 1904 calendars cannot retain both original numeric/calendar/date-function meanings under one workbook date-system flag; keep those workbooks separate or explicitly change their source representation.
• Supported absolute local names, contiguous table selectors and whole-column criteria share source-derived geometry. Relative/disjoint named ranges and unproved date-formula bounds can refuse. Existing array-mask, style-run and Excel formula-length bounds remain unchanged; no new input limits are introduced by this repair.
• Pivot cleanup verifies source/cache coherence and rebuilds supported saved views. More complex column/layout and dynamic label/value/Top10 filtering profiles still need graph-aware summary mapping. Calculated fields using unsupported functions or derived fields, deletion-sensitive or unproved source formulas, external/OLAP connections and unfamiliar extensions stop explicitly. These profiles retain existing guards and are not universally qualified.
• Embedded PNG/JPEG/SVG drawing content and supported source-theme graphs are retained. Missing external pivot or image dependencies name the exact linked resource. In Excel, point the PivotTable to a local sheet/table or insert the picture without Link to File, Refresh/save as appropriate, then select the saved XLSX again. Adding a companion file as another merge input does not reconnect an external link; active or externally dependent SVG refuses. Unfamiliar drawing extensions and unsupported linked-text expressions require exact mappers. Explicit source font slots are retained without guessing glyph substitutes. Cross-font geometry requires available source fonts and the observed display grid; other readers/DPI/zoom/font-substitution environments are not universally qualified. Use100% browser zoom and inspect the final in the intended application.
• Formula values are recalculated by a compatible reader; preview shows expressions rather than stale cached values. Original file downloads preserve exact source bytes. CSV is intentionally data-only. The stated supported-feature qualification is unchanged.