Merge CSV Files

Merge CSV Files is a free browser-based tool that helps you combine multiple csv files into one. It is part of ToolsMonk's ms office tools collection, so you can finish the job without downloading software, creating an account, or jumping between multiple websites.

This tool is especially useful for workflows such as combining monthly or split csv exports into one file, stacking data from multiple sources into a single dataset, and consolidating csvs before analysis or import. Because it runs directly in your browser, you can use it on desktop, tablet, or mobile while keeping the process fast and easy for one-off tasks as well as repeat work.

Merge CSV Files is designed for people who want a practical, privacy-friendly workflow with instant results inside the larger ToolsMonk library.

CSV Merge combines multiple CSV files into a single CSV by stacking their rows together, keeping one shared header — the quick way to consolidate split or periodic exports into one dataset.

It works by appending each file's data rows beneath the first, so several monthly exports become one continuous file ready for analysis or a single import. For this to work cleanly, the files should share the same column structure — identical headers in the same order — so the data lines up; mismatched columns can misalign values.

One thing it deliberately doesn't do is de-duplicate: every row from every file is kept, so a record appearing in multiple files appears multiple times. If you need unique rows, run the combined output through Remove Duplicate Lines afterwards.

Merging runs in your browser, so your data — often many records — stays on your device, with the practical size limit being your browser's memory. Pair it with the CSV to JSON/Excel and Remove Duplicate Lines tools for a complete CSV cleanup and conversion workflow.