Free online CSV & spreadsheet tools
Clean, convert, and chart your data — each tool does one job well, with no spreadsheet formulas, no install, and no upload. Your file is processed entirely in your browser, so it never reaches our servers.
Remove duplicates from CSV
Delete duplicate rows by any column, keep the first or last match, and download a clean file.
Open tool →Clean phone numbers
Format a messy column of phone numbers to the E.164 standard, with no upload.
Open tool →Clean email column
Lowercase, trim, validate, and dedupe an email column in a CSV — entirely in your browser.
Open tool →Split full names
Break a full-name column into separate first and last name fields, with optional middle name.
Open tool →Combine columns
Merge two or more CSV columns into one — pick a separator and name the new field.
Open tool →Find and replace in a CSV
Swap text in a column like Excel's Find & Replace — match case or whole cell, with no upload.
Open tool →Convert CSV to Excel
Turn a CSV into a formatted .xlsx workbook in your browser — no upload, no install.
Open tool →Convert Excel to CSV
Export the first sheet of an .xlsx or .xls file to a clean CSV — entirely in your browser.
Open tool →Visualize a CSV as a chart
Summarize a spreadsheet into a bar, line, area or pie chart and export the image — nothing uploaded.
Open tool →What data cleansing tools do
Data cleansing tools fix the four faults that make a fresh export unusable: duplicate rows, values in an inconsistent format, text stuck in one column that belongs in two, and whitespace you cannot see. Desktop CSV software makes you install it first, and most online CSV tools make you upload the file first. These do neither — each one is a page that reads the file in the tab.
The order matters more than the tools. Run a messy file through this sequence:
- Strip stray characters. Trailing spaces, stray quotes, and placeholder text like “N/A” all defeat an exact match later. Use find and replace on a CSV column.
- Standardise formats. Phone numbers to E.164 with the phone number formatter, addresses lowercased and trimmed with the email column cleaner.
- Fix the column layout. Break one field into two with split full names, or merge two into one with combine columns.
- Deduplicate last. Only now will the CSV duplicate remover catch the records two spellings apart. The same logic applies to the Remove Duplicates button in Excel.
- Hand it off. Export as a workbook with CSV to Excel, or sanity-check the result as a chart before you import it anywhere.
Every step above previews in full for free — the download counter only ticks when you export the finished file. For the reasoning behind the sequence, see what data cleaning actually involves.
Frequently asked questions
- What are data cleansing tools?
- Data cleansing tools find and fix the errors in a dataset that stop it being usable: duplicate records, values in the wrong format, text stuck in one column that belongs in two, and stray whitespace. Sigmera splits that work into one tool per problem so you can run only the passes your file needs.
- Are these online CSV tools free?
- Opening a file, configuring a clean-up, and previewing the full result is free and unlimited on every plan. The free plan includes 3 downloads a month with no credit card; Pro is $15 a month for 30 downloads and Max is $39 for unlimited. Rows and file size are unlimited on all three.
- Do I need to install any CSV software?
- No. Every tool is a web page that loads a JavaScript engine into the tab and reads your file with the browser's own File API. There is nothing to install, nothing to update, and no admin rights needed — which is why this works on a locked-down work laptop.
- Is it safe to clean a customer list in a browser tool?
- With Sigmera, yes, because the file is never transmitted. Parsing and cleaning happen in the browser tab on your own machine, so the CSV containing names, emails, or phone numbers never reaches our servers. There is no processor and no data transfer, which removes most of the GDPR questions that a normal upload-based tool raises.
- Which tool should I use on a messy export?
- Work in this order: find and replace to strip stray characters, then the phone and email cleaners to standardise formats, then split or combine columns, then remove duplicates last. Deduplicating before you normalise misses matches, because two spellings of the same record are still two different strings.
- How large a file can these tools handle?
- There is no row cap or file-size cap on any plan. The practical limit is your own machine's memory, since the whole file is held in the browser tab — in exchange, a large file costs nothing in upload time because it never leaves the device.