Find & Replace Across Many Excel/CSV Files and Columns

About the Find & Replace Across Many Excel/CSV Files and Columns

Rename a customer, correct a product code, standardise state names or swap old prices for new ones in dozens of spreadsheets at once. Add your CSV, TSV and Excel files (or one workbook with many sheets), give a list of find → replace pairs — typed, pasted from a spreadsheet, or loaded from a two-column mapping file — and choose the columns, whole-cell or partial matching, upper and lower case and regular expressions. Before anything is written you see how many cells each file, sheet and pair would change, and the first changes themselves.

The changed files come back in one ZIP with a change log: every cell, its old value and its new one. Only values change. In CSV files just the changed fields are rewritten — quotes, line breaks and the encoding stay as they were — and Excel workbooks keep their formatting, formulas, charts and every sheet you did not change. Cells with formulas are never rewritten: when a formula or its result holds a text to find, the log lists it so you can change it yourself. Everything runs in your browser; nothing is uploaded.

Common uses

• Applying a renamed customer, supplier or product name to every report and export.
• Correcting codes (SKUs, account codes, branch codes) from a list of old and new codes.
• Standardising spellings across files before merging or importing them.
• Updating a value in every sheet of a large workbook without opening each sheet.
• Keeping a record of exactly which cells were changed, for an audit or a review.

How the pairs are applied

• Each cell is changed in one pass: replacements are never searched again, so a → b and b → c turn “ab” into “bc”, not “cc”.
• Where several texts to find start at the same place, the longest one wins (New York before New). With regular expressions the pairs are tried in the order of the list.
• Whole cell compares the entire cell (spaces at its start and end ignored, unless you turn that off); part of a cell replaces every occurrence inside it.
• In Excel files, number cells are changed only with whole-cell matching: 1001 → 2001 changes the code 1001, but a partial match never rewrites the digits of an amount. A replacement that is a number stays a number.
• In Excel files, dates and times, TRUE/FALSE values and error values are not changed, and neither is any cell with a formula. In CSV files every field is text, so a date written there is matched like any other text.

What the changed files keep

CSV and text files keep every byte that did not change: the delimiter, the quotes, the line breaks and the encoding (UTF-8 with or without a byte-order mark, UTF-16, Windows-1252 and the other single-byte encodings). If a replacement has a character the file’s encoding cannot hold, that file is saved as UTF-8 instead and the result says so.

XLSX and XLSM workbooks keep their fonts, colours, borders, formulas, conditional formats, charts, pictures, comments and macros: only the cells of the sheets that changed are written again. Excel recalculates the formulas when it opens a changed file, so totals that depend on changed values are up to date. Older formats (XLS, ODS, Numbers) are saved as .xlsx with their values and formulas, without their formatting.

Limitations

• Up to 200 files and 250 MB at a time; each workbook up to 50 MB.
• Text inside formulas, charts, comments, text boxes, sheet names and defined names is not changed; formula cells that hold a text to find are listed in the change log instead.
• A cell with formatting inside its text (one word bold) gets the new text as plain text; the log says which cells.
• Workbooks encrypted with a password to open cannot be read.

Privacy

Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot.