Merge CSV Files Online
Combine multiple CSV files into a single structured spreadsheet. Align columns by header names or concatenate files by row index instantly in your browser.
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Upload two or more CSV files to preview merged rows.
Comprehensive Guide to Merging CSV Files Online
How does the Smart Merge (Align Headers) strategy work?
When you select **Align Headers**, our tool inspects the column headings of each uploaded CSV file. It compiles a master list of all unique columns. During the merge, if a file does not contain a specific column, the tool automatically inserts empty cells for that file's rows. This ensures that columns with the same name are aligned perfectly, even if they appear in a different order or are missing from some files.
What is the difference with Row Stacking (Append)?
If your CSV files do not have column headers but contain identical structured data (e.g. column 1 is always First Name, column 2 is always Last Name), you should use **Stack Rows (Append)**. This strategy ignores text header lines and merges files strictly by column indexes. It simply pastes rows of subsequent files underneath the preceding ones.
Frequently Asked Questions (FAQ) – CSV Merger
Is there a file size limit for merging CSVs?
Since the calculations occur entirely inside your browser's runtime environment, the limitation is determined by your system's available memory. It can comfortably process files up to 50MB with hundreds of thousands of rows.
How does the delimiter auto-detection work?
The auto-detector parses the first few lines of each uploaded CSV file and counts occurrences of standard separators (commas, semicolons, tabs, and pipes). The separator with the highest count is used. If your file has non-standard values, you can set the delimiter manually.
Are my files safe? Do you store any of my data?
Agnixbit is 100% serverless and local-first. All parsing, headers alignment, and merging actions take place in memory directly on your computer. Your file data is never sent to any server, offering absolute privacy.
Can I merge files with different column orders?
Yes. If you choose the "Align Headers" option, the tool will dynamically search for column names and map row fields to their respective columns, regardless of their position in the individual files.