Merge Two Excel Files
Fill missing columns in one spreadsheet from another, matched on a shared key.
Two spreadsheets, one column they both carry. Pick them below and the missing fields are copied across.
No file yet.
No file yet.
Guide & FAQWhat it does · The three things that go wrong · Your formatting stays · Dates · Password-protected workbooks · Nothing is uploaded · Frequently asked questions
What it does
You have a list of orders with a customer ID but no customer name, and a second sheet that has both. This walks down the first sheet, looks each ID up in the second, and writes the name into a new column. It is what VLOOKUP or XLOOKUP does, without writing the formula, getting the range wrong, or ending up with a column of #N/A you then have to hunt through.
The three things that go wrong
Keys that look identical and are not. A trailing space, or ACME against Acme, is the most common reason a lookup returns nothing for rows you can see are there. Matching ignores case and surrounding whitespace unless you turn that off.
Duplicate keys in the second file. If an ID appears twice there, only the first row can win. That is the same thing VLOOKUP does silently; here the count is reported, because two rows for one ID usually means the file is not what you thought it was.
Rows that match nothing. Those keep their new columns empty and are counted, so you know whether you filled 998 rows out of 1,000 or 40 out of 1,000 before you send the file on.
Your formatting stays
The .xlsx you download is the first file itself, not a new workbook with its values copied in. The new columns are inserted into that sheet where you choose — after any column, or before the first — the way Excel's own Insert Column works. Everything else in the file is carried over untouched: other sheets, fonts, fills, borders, column widths, frozen panes, charts and pictures. Anything that points at a cell by its column is moved along with it, so formulas, merged cells, filters, tables, data validation, conditional formatting and comments still point at the same data afterwards.
Each new cell takes the style of the cell to its left, so a bold header stays bold and a bordered table stays bordered. Numbers and dates keep that look but get their own number format, so a column of prices placed next to a date column does not turn into dates.
Dates
A date in a spreadsheet is stored as a number counting days from 1900, and which of those numbers is a date is decided by the cell's format rather than the value. The number formats are read so dates come out as dates rather than as five-digit numbers. The 1904 date system that older Mac files use is handled too.
Password-protected workbooks
A workbook with a password is not a zip at all: it is a container holding the real file under AES, with the key stretched from your password by tens of thousands of hash rounds. Type the password and that happens here, in the tab, which takes a second or two and is the whole point — a file somebody bothered to lock is the last file worth handing to a website. Both the Office 2007 scheme and the one used since 2010 are read. Neither the password nor the file is sent anywhere.
Nothing is uploaded
Both files are read with the browser's own file reader and unzipped in the tab. There is no request carrying your data anywhere, which for a sheet of customers, salaries or phone numbers is the only arrangement worth having.
Frequently asked questions
Does this replace VLOOKUP?
For the common case of copying columns from one sheet into another on a shared key, yes. VLOOKUP is still the tool when the lookup has to stay live and update as the source changes — this produces a finished file.
What happens if the same ID appears twice in the second file?
The first row wins and the number of duplicate keys is reported. VLOOKUP behaves the same way without telling you, which is why the count is shown: two rows for one ID usually means the second file has a different granularity than you expected.
Why are my dates showing as numbers like 45678?
A five-digit number where a date should be is the raw serial a spreadsheet stores dates as, counting days from 1900. This tool reads the cell number formats to tell dates from ordinary numbers, so it should not happen here. If it does, the cell was formatted as a plain number in the source file.
Does the result keep my formatting?
Yes. The download is your first workbook with the new columns inserted after the column you pick, not a rebuilt copy. Styles, widths, other sheets, charts, formulas, merged cells and filters are all kept, and references that pointed past the insert are moved so they still point at the same cells. If the first file is a CSV there is no formatting to keep, and a plain workbook is written instead.
Is my data uploaded anywhere?
No. The files are read and unzipped in your browser, the merge runs there, and the download is generated there. Nothing is sent to a server, so a sheet of customer names or salaries never leaves the machine.
Which files can it read?
xlsx and xlsm from Excel, Google Sheets, LibreOffice and Numbers, plus CSV. Password-protected workbooks are opened in the browser once you type the password, covering both the Office 2007 scheme and the newer one. The old binary .xls format is not readable — open it in Excel once and save it as .xlsx.