--- title: "CSV merger" description: "Merge two or more CSV files into one, with columns lined up by header name and repeated email addresses dropped if you like. Free, in your browser." canonical: https://www.acquisity.ai/tools/merge-csv-files --- # CSV merger > Merge two or more CSV files into one, with columns lined up by header name and repeated email addresses dropped if you like. Free, in your browser. Add two or more CSV files. We line up their columns by header name and give you one CSV file to download. It runs in your browser, so your files never leave your computer. Use the tool in a browser at [/tools/merge-csv-files](https://www.acquisity.ai/tools/merge-csv-files). It is free and needs no sign-up. ## How the files are merged - With First row is a header on, as it is at the start, each file’s first row names its columns. Columns with the same name are lined up, whatever their capitals and the spaces around the name, so Email, email and EMAIL are one column. - The merged file has every column from every file, in the order they first appear. Where a file has no such column, its rows get an empty cell there. With First row is a header on, a column with no name and nothing in it in any file, like the empty ones Excel can leave at the end of each row, is left out. - With First row is a header off, rows are stacked by position, first column under first column. - Each file can use commas, semicolons or tabs between its cells; we work out which from the file. Files saved as UTF-8 and files saved in Excel’s older Windows format for Western European languages (Windows-1252) are both read. Save a file in another language from Excel as CSV UTF-8 first. Cells in quotes keep their commas, quotes and line breaks. - Rows keep their order: every row of the first file, then every row of the second, and so on. Blank rows, with nothing but spaces or empty cells, are skipped. - The merged file uses commas and UTF-8, marked so that Excel shows accented letters as they are. A cell that starts with =, +, - or @ gets an apostrophe in front, so a spreadsheet shows it as text instead of running it as a formula. ## Dropping repeated email addresses Tick Drop rows that repeat an email address to keep only the first row for each address. With First row is a header on, as it is at the start, repeats are checked only in files with an email column we recognize, the same ones our compare two lists tool reads, and only in those columns. Email, Work Email and Google Contacts’ E-mail 1 - Value count. A column for someone else’s address or a shared inbox, like Owner Email or Company Email, never counts. A file with no email column we recognize, like one whose addresses sit under Contact or under a name in another language like Courriel, is left as it is, and the result names it. With First row is a header off, there are no column names, so every column counts, and a file with addresses in more than one column isn’t checked. Addresses match whatever their capitals, so Sam@Acme.com and sam@acme.com are the same person. A row with no valid address there, or with more than one, is always kept. The result says how many rows were dropped, and it never says no row repeated when a column it didn’t read held an address, or an email cell held an @ but no address it could read, like sam@acme.com (work). ## What it doesn’t do It doesn’t read Excel files (.xlsx), so save each sheet as CSV first. It doesn’t join files side by side on a matching column: it adds the rows of one file below the rows of another. Your files are read in your browser and aren’t uploaded or saved. ## Questions ### How do I merge CSV files into one? Choose two or more CSV files, or drop them on the page. They merge as soon as there are two, and Download CSV saves the merged file. ### Can I merge CSV files with different columns? Yes. Columns are lined up by their header names, the merged file has every column from every file apart from empty ones with no name, and a row gets an empty cell for any column its file doesn’t have. ### Can I merge CSV files that use semicolons or tabs? Yes. Each file is read with its own separator, comma, semicolon or tab, and the merged file uses commas. ### Does it remove duplicate rows? It can drop rows that repeat an email address, keeping the first one. Tick Drop rows that repeat an email address. It reads addresses only from email columns it recognizes, like Email or Work Email, never from one for someone else or a shared inbox, like Owner Email or Company Email, and it names any file it didn’t check. With First row is a header off, it reads every column and names a file with addresses in more than one. Rows with no valid email address there, or more than one, are always kept. ### Can I merge Excel files? Not directly. Save each sheet as CSV in Excel or Google Sheets, then add the CSV files. ### Are my files uploaded or stored? No. Your files are read and merged in your browser, and they’re never sent to us or saved. ### How big can the files be? Up to 10 MB each, which holds about 100,000 rows of a lead list with a handful of columns. Past that, we merge the first 10 MB of that file, up to the last whole row, and say so. ## Merging lead lists before a campaign? On paid plans, when you upload leads to a campaign, Acquisity skips repeats, invalid addresses, people on your blocklist and people already in another campaign you haven’t archived, and shows you what it skipped. [Cold Email Agent](https://www.acquisity.ai/agents/cold-email). --- Web page: https://www.acquisity.ai/tools/merge-csv-files Site index for agents: https://www.acquisity.ai/llms.txt