Do all files need identical columns?

No — missing columns are filled with empty values. Use column mapping to align different headers.

Is the header row duplicated?

No — only the first file header is used.

No. Everything runs locally in your browser.

Process files up to the browser memory limit.

Free plan: up to 10 files. Pro: much higher limits.

Merge multiple CSV files with the same structure into a single file vertically. Processed entirely in your browser for 100% d

Your files never leave your device. Processed locally. 100% private.

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Complete your task perfectly in just three straightforward steps.

Drop two or more CSV files with the same column structure.

Drag files to set the vertical append order.

Download the merged CSV.

Everything you need to know about the CSV Merger.

Continue working with our suite of free data utilities.

Filter CSV rows by conditions on any column. Supports AND/OR logic. The safest way to process sensitive data with zero-upload

Transform wide CSV tables to long format. Convert column headers into row values. Processed entirely in your browser for 100%

Sort CSV rows by one or more columns in ascending or descending order. Fast, private, and secure browser-based tool with no s