Trim whitespace
Remove leading and trailing spaces from every cell — a common cause of failed joins, broken lookups and values that look the same but do not match.
Data preview100 rows per page
Drop a CSV up to 100 MB. Trim whitespace, detect data types, remove empty rows, deduplicate and export — with processing kept on your device.
Your original file is never modified.
What it does
Exports from databases, CRMs and spreadsheets often carry invisible problems. LeanCSV helps you inspect and clean the data before it reaches your next workflow.
Remove leading and trailing spaces from every cell — a common cause of failed joins, broken lookups and values that look the same but do not match.
Convert a selected column to UPPERCASE, lowercase or Capitalized Text. Standardize product codes, city names, status fields and contact data.
Clear records and columns where every cell is blank, helping reduce accidental padding from copy-paste and spreadsheet exports.
Classify sampled values as numbers, dates, booleans or text. Colour-coded labels update after a cleaning operation so you can review the current data.
Remove exact duplicate rows. Review the duplicate count before cleaning, and trim whitespace first when spaces should not make a row unique.
Inspect up to 100 rows at a time with sticky headers and horizontal scrolling. Review the cleaned table before exporting the new CSV.
Use cases
Clean the everyday CSV files that sit between your source system and the next step in your workflow.
Prepare CSV data before importing it into PostgreSQL, MySQL or SQLite. Trim padded values, remove blank records and catch exact duplicates before they reach unique constraints.
Standardize contact names and status fields, remove duplicate rows and clean exports from CRM or email marketing platforms before migrating or running a mail merge.
Remove empty rows and columns that appear after copying data between Excel, Google Sheets and other spreadsheet tools.
Inspect column counts, likely data types, empty records and duplicate counts before a file enters a transformation or import pipeline.
Use local browser processing when you do not want to send a CSV to a third-party file-processing service. Keep in mind your browser and hosting provider still load the app itself.
Clean blank records, normalize category casing and remove duplicate rows before preparing product data for a shop or marketplace.
Why LeanCSV
Small data issues can turn into failed imports, mismatched records and avoidable cleanup later. LeanCSV helps you get a clearer, more consistent CSV before you use it somewhere else.
Remove blank rows and columns, trim stray spaces and clear exact duplicates before a file reaches your database, CRM or spreadsheet.
Review row and column counts, empty records, duplicate rows and likely column types before you rely on the data.
Normalize text casing in a selected column to reduce inconsistencies that can complicate searching, sorting and record matching.
Clean everyday business or personal datasets without handing the CSV to a third-party file-processing service.
Your original file on disk is not overwritten. Download a separate cleaned CSV when the data looks right.
No account, no installation and no script to write. Open a CSV, make the changes you need and export the result.
FAQ
Yes. LeanCSV is free to use and does not require an account. All current cleaning and export features are available in the browser.
No. The CSV content is read and processed locally in your browser. The app does not send your file to a file-processing server. The website itself still loads its page assets, and any external font or hosting requests are separate from the file contents.
LeanCSV detects comma (,), semicolon (;), tab and pipe (|) separators. The detected separator is used again when exporting.
The file-size limit is 100 MB. The browser still needs memory for the parsed rows and temporary copies used by some operations, so actual capacity depends on the number of rows and columns, the browser and available RAM. Close memory-heavy tabs or split unusually large files if processing becomes slow.
Yes. Quoted fields, escaped double quotes (""), delimiters inside quoted fields and quoted line breaks are supported, along with common CRLF and LF line endings.
LeanCSV samples up to 200 non-empty values per column and checks for numbers, dates and common boolean values. A non-text type is shown only when the sample mostly matches that type, reducing false positives in mixed columns.
No. Duplicate detection compares cell values as they currently exist. Run Trim spaces first when leading and trailing whitespace should not distinguish otherwise identical rows.
There is no multi-step undo stack yet. Use Reset and upload the original file again to start over. The file on your disk is never modified.
Use a modern desktop browser with support for Web Workers, the Streams API and TextDecoder, such as a current version of Chrome, Firefox, Safari or Edge. Large files work best with adequate free memory.
LeanCSV currently works with CSV files. Export an Excel workbook as CSV from your spreadsheet software before opening it here.