About RowSlice

RowSlice is a small, independent set of free tools for one specific problem: CSV files that are too large, too messy or too sensitive for the usual ways of handling them.

Why It Exists

Data exports keep getting bigger, while the everyday tools for handling them have not changed. Excel stops at 1,048,576 rows and quietly changes values like ZIP codes and long IDs. Most online CSV tools either require uploading files to someone else's server, which many workplaces forbid, or load the entire file into the browser and fail once it gets large. Splitting an export by region or combining a folder of reports should not require writing code.

How the Tools Work

When you choose a file, it is opened by JavaScript running in your own browser tab. The file is read a few megabytes at a time and parsed according to the CSV standard (RFC 4180), and results are written to your browser's private storage on your own disk. When you download the result, it is copied from there to your downloads folder. No part of your file is sent to RowSlice or anyone else.

Because of this, memory use stays low regardless of file size, and the limit on how large a file you can process is your free disk space. It also means the tools keep working if you disconnect from the internet after the page has loaded.

Principles

• Correctness first. Rows are copied as text, never reinterpreted, so values come out as they went in.
• No upload, no account. The core tools are free to use without signing up.
• Plain explanations. Every tool page explains what it does to your data and what its limits are.

Contact

Found a file the tools handle incorrectly, or need a CSV job they don't do yet? Email hello@rowslice.com. Please don't attach confidential data; a few made-up rows that show the problem are usually enough.