About LeanCSV
What is LeanCSV?
LeanCSV is a free CSV cleaning and inspection tool that runs entirely in your browser. There is no account to create, no file to upload, and no server involved. Drop in a CSV — up to 100 MB — and you get an instant, interactive view of your data with one-click tools to fix the most common quality problems.
Who it's for
LeanCSV is built for anyone who works with tabular data and needs to clean it quickly without writing code. That includes data analysts preparing files for import, developers auditing pipeline inputs, operations teams standardizing CRM exports, HR teams cleaning payroll files, and anyone handling sensitive data that cannot be uploaded to a third-party service.
What it does
- Trim whitespace — removes leading and trailing spaces from every cell in the file.
- Remove empty rows and columns — deletes rows and columns where every cell is blank.
- Deduplicate rows — identifies and removes exact duplicate rows across all columns.
- Case normalization — converts any column to UPPERCASE, lowercase or Title Case.
- Automatic type detection — classifies each column as number, date, boolean or text and displays colour-coded badges in the table header.
- Paginated table preview — shows your data 100 rows at a time with sticky, typed column headers.
- Export — downloads the cleaned file as a CSV using the same delimiter as the original.
Up to 100 MB — in your browser
Most browser-based data tools struggle with large files or refuse to process them at all. LeanCSV handles CSV files up to 100 MB without an upload, without a server, and without freezing your tab. Large exports from your CRM, data warehouse or analytics platform are processed the same way as small ones — instantly and locally.
Private by design
Your file never leaves your device. No content is transmitted over the network during processing. LeanCSV is a static site — there is no backend, no database, and no system that could receive or store your data. This makes it safe to use with files that contain PII, financial records, health information, or any other sensitive data that cannot be shared with a third party.
Free, no account required
Every feature in LeanCSV is available to everyone at no cost, with no account, no daily limit, and no watermark on exported files. LeanCSV is part of RuntimeHub — a suite of free, privacy-first, browser-native tools built for people who work with data and code.
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