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.
A performant browser sandbox that puts your device to work — your own high-performance computing unit for everyday CSV cleanup.
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.
Practical guide
A few deliberate checks can prevent common data problems later. Use this workflow before importing a CSV into a database, moving it between spreadsheets or sharing it with another team.
Check the row and column counts, look for empty records and columns, and review the duplicate count. Column type labels are useful clues, but they are not a substitute for checking what a field means.
Trim leading and trailing spaces when they are accidental. Normalize capitalization in fields such as categories or status labels, but preserve case-sensitive values, passwords, tokens and identifiers exactly as required by the destination system.
Remove rows or columns that are entirely empty. Deduplication removes rows with matching cell values; it does not decide whether two different customer records represent the same person.
Review the cleaned rows and column labels, then export a separate CSV copy. Pay special attention to product codes, postal codes and account IDs that may contain leading zeros and should remain text.
FAQ
Yes. LeanCSV is free to use and does not require an account. The current cleaning, inspection and export features are available without a subscription or usage tier.
No. The CSV content is processed on your device and is not sent to a file-processing server. The website still loads its page assets, and normal hosting or website requests are separate from the contents of your CSV.
LeanCSV recognises comma (,), semicolon (;), tab and pipe (|) separated files. The detected separator is retained when you export the cleaned CSV.
The maximum accepted file size is 100 MB. Actual working capacity depends on the number of rows and columns, the browser and the memory available on your device. Very wide files or files with many complex fields can require substantially more memory than their file size suggests.
Yes. LeanCSV supports quoted fields, escaped double quotes (""), separators inside quoted values and line breaks inside quoted fields. Common CRLF and LF line endings are supported as well.
LeanCSV reviews values in each column and labels the column as a likely number, date, boolean or text field. These labels are quick indicators that help you inspect a dataset; they do not convert values or guarantee that a column matches a database schema.
No. Duplicate detection compares the cell values as they currently appear. Run Trim spaces first when accidental leading or trailing spaces should not make otherwise matching rows different.
There is no multi-step undo history at the moment. Use Reset and upload the original file again to start over. LeanCSV does not overwrite the source file on your device.
Use a current version of Chrome, Firefox, Safari or Edge. For larger datasets, a desktop browser with sufficient free memory will generally provide a more comfortable experience than a memory-constrained mobile device.
LeanCSV currently works with CSV files, not native Excel workbooks. In Excel, LibreOffice Calc or Google Sheets, export or download the worksheet as a CSV file before opening it in LeanCSV.