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FindChanged compares two files and shows what changed. It currently works with Excel and CSV spreadsheets, and lets you edit, sync and export the result. Everything happens in your browser.

Your files stay on your computer

Files are read and compared only in this browser tab. They are never uploaded, and nothing is kept after you close the page, so export your changes before you leave. The page warns you if you try to close it with unexported changes.

Getting started

Open the workspace and choose a left file and a right file (.xlsx, .xls or .csv).
Choose how rows are matched, then click Compare.
Review the differences, edit cells or copy values from one side to the other, and export either side as a new file.

How rows are matched

By key columns: Rows with the same value in the key column (for example ID) are paired. Use several key columns, separated by commas, when one column is not unique.
By row position: Row 1 is paired with row 1, row 2 with row 2, and so on.
No ID (identical rows): Rows whose contents are exactly the same are paired; everything else is shown as left-only or right-only.

Columns are matched by header name. Open Columns… to pair or unpair columns by hand. If the automatic row pairing is wrong, right-click a row to pair or unpair it.

Editing and syncing

Double-click a cell to edit it; press Enter to keep the change or Esc to cancel.
Right-click a row to copy it to the other side, delete it, move it up or down, or change its pairing.
Sync all makes one side identical to the other. It also covers rows hidden by the filter, and asks first.
Every change can be undone and redone.
The difference overview above the table squeezes all rows into two strips (left file on top, right file below): orange means changed, blue means the row exists only on that side, and grey means that side has no record. The frame marks the part shown in the table; click or drag to jump.
Lock pairing keeps the pairs fixed; while it is on you can sort by clicking a column header.
Click rows to select them (Shift for a range, Ctrl or ⌘ to add rows), then press Ctrl+C / ⌘+C to copy them as tab-separated text that pastes straight into a spreadsheet.

Keyboard

The table can be used entirely from the keyboard. Press Tab to move into the table; a blue box marks the current cell:

Arrow keys	Move; Home / End go to the start or end of the row, Ctrl+Home / Ctrl+End to the first or last row, Page Up / Page Down by a screen
Enter or F2	Edit the current cell. Typing a letter or digit also starts editing. When using an input method (for example for Chinese), press Enter or F2 first
While editing	Enter saves and moves down, Tab saves and moves right, Esc cancels
Delete	Clear the current cell (can be undone)
Space	Select the current row; Shift and Ctrl work as with the mouse
Shift+F10	Open the row menu; arrow keys to choose, Enter to run, Esc to close
Ctrl+C / Esc	Copy the selected rows / clear the selection
← / → in the overview	Jump to the previous / next difference; Home / End go to the start / end

Exporting

Each side is exported to a new file; your original files are never changed. Only the compared worksheet is exported, without formulas or formatting (formulas are exported as their last calculated values).

For a CSV that Excel will open by double-clicking, choose UTF-8 with BOM. Without the BOM, Excel may show non-English characters as garbage.
Other encodings: GB18030, Windows-1252, Big5 and Shift_JIS. If a character cannot be written in the chosen encoding, the export stops and shows where it is, rather than replacing it.
Delimiters: comma, semicolon (common in European versions of Excel) or Tab.
Safe for spreadsheet apps adds an apostrophe before values that start with = + - @ so they are not run as formulas. This changes the values, so leave it off unless you need it.

File size limits

For each side:

Rows	50,000
Columns	200
Cells (rows × columns)	2,000,000
Text in one cell	32,767 characters (the same as Excel)
File size	30 MB (an .xlsx may expand to at most 300 MB)

Files near these limits take 10–25 seconds to read or export and can use about 3 GB of memory in the browser. For large files we recommend a computer with 16 GB of memory; with less, the browser tab may run out of memory and close. You can cancel reading at any time without losing your current work.

Supported browsers

The current and previous major versions of Chrome, Edge, Firefox and Safari on a desktop computer. Phones and tablets can open the workspace, but editing is not designed for small screens.

Problems and suggestions

Use the Feedback button at the top of the workspace. You will get a reference number. Your files are not sent with your feedback; only attachments you add yourself are.