Merge multiple CSVs, remove duplicates, transform data, and export clean files. All processing happens in your browser—fast, private, and free.
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A powerful browser-based tool for cleaning, transforming, and merging CSV files. All processing happens locally—your data never leaves your device.
After uploading your CSV, you'll enter the transformation editor with three resizable panels. Drag the borders between panels to resize them.
The left panel displays all columns in your CSV file. Each column shows its name, detected data type (text, number, or date), and fill percentage indicating how many cells contain data.
The middle panel is where you choose and configure transformations. Actions are organized into logical groups: Text, Values, Columns, and Rows. Applied transformations appear in a list below with a Clear All button.
The right panel shows a live preview of your CSV data. You can toggle between the original data and the cleaned version to see exactly what changes your transformations will make. You can also directly edit any cell value by clicking on it, and drag column headers to reorder columns.
Your data never leaves your browser. Unlike many online tools that upload your files to remote servers, we process everything locally using JavaScript.
Detailed documentation for all available transformations. Click to expand each section.
Text transformations modify the content of cells in your selected columns. These are useful for standardizing text formatting, cleaning up messy data, and removing unwanted characters.
Removes extra spaces from the beginning and end of cell values. This is essential for cleaning data imported from various sources where invisible spaces can cause matching and sorting issues.
Converts all text in the selected columns to uppercase letters. Useful for standardizing codes, abbreviations, or creating consistent formatting for headers and labels.
Converts all text in the selected columns to lowercase letters. Ideal for normalizing email addresses, usernames, or creating case-insensitive comparison keys.
Capitalizes the first letter of each word while making the rest lowercase. Perfect for formatting names, titles, addresses, and other proper nouns consistently.
Strips out special characters like @, #, $, %, etc., keeping only letters, numbers, and basic punctuation. Useful for cleaning data that will be used in systems with character restrictions.
Removes all non-ASCII characters including emojis, special symbols, and characters from non-Latin alphabets. Essential for ensuring compatibility with legacy systems that only support ASCII.
Standardizes different line break formats (Windows CRLF, Mac CR, Unix LF) into a single consistent format. Also removes excessive multiple line breaks.
Value transformations allow you to replace or modify specific cell values. These are powerful tools for data standardization, fixing typos, and handling missing data.
Fills empty or blank cells with a custom default value that you specify. This ensures your data is complete and prevents issues when processing files that require all fields to have values.
Searches for a specific text string and replaces all occurrences with a new value. Works across all selected columns simultaneously. Perfect for fixing typos, updating outdated values, or standardizing terminology.
Column transformations modify the structure of your CSV file by removing or renaming columns. Use these to clean up your data schema and prepare files for specific import requirements.
Completely removes the selected column(s) from your CSV file. The column header and all data in that column will be excluded from the cleaned output file.
Changes the header name of a column while keeping all the data intact. Only one column can be renamed at a time to ensure you specify the correct new name for each column.
Rearrange the order of columns by dragging and dropping column headers in the Data Preview panel. The new column order is preserved when you download the file in any format (CSV, Excel, JSON, TSV).
In addition to applying transformations, you can directly edit any cell value in the Data Preview panel. Cell edits are treated as corrections to the source data and are processed BEFORE transformations are applied.
Click on any cell in the Data Preview panel (when viewing Cleaned data) to edit its value directly. This allows you to fix individual data errors, correct typos, or make one-off changes without creating a transformation rule.
Cell edits are applied BEFORE transformations. This means any transformation you add will also apply to your edited values. For example, if you edit a cell to 'john smith' and then apply an UPPERCASE transformation, the final result will be 'JOHN SMITH'.
Cell edits and transformations have separate reset buttons. 'Reset Edits' (amber button in Data Preview) clears only cell edits and column order. 'Clear All' (rose button in Transformations panel) removes only transformations. This allows you to independently manage edits and transformations.
Row transformations affect entire rows of data based on the values in selected columns. Currently, this category includes the powerful duplicate removal feature.
Identifies and removes duplicate rows based on the values in your selected columns. Only the first occurrence of each unique combination is kept. This is one of the most powerful features for data deduplication.
Need to combine data from multiple CSV files? Our tool makes it easy to merge files while handling different column structures automatically.
When uploading, hold Ctrl (Windows) or Cmd (Mac) to select multiple CSV files, or drag and drop multiple files at once. You can merge up to 20 files.
A merge preview screen shows you statistics about each file including row counts, column counts, and how the columns will be combined. Files with different column structures are automatically handled.
The tool creates a unified column schema containing all unique columns from all files. If a column exists in some files but not others, empty values are used for the missing data.
After merging, you can apply any of the transformation features to clean the combined dataset before downloading.
Download your cleaned CSV in multiple formats to suit your needs. All formats preserve your transformations and column order.
Comma-Separated Values – the standard format for spreadsheet data exchange. Compatible with Excel, Google Sheets, databases, and virtually any data processing tool.
Microsoft Excel format with full workbook support. Opens directly in Excel, LibreOffice Calc, Google Sheets, and other spreadsheet applications without any import steps.
JavaScript Object Notation – exports your data as an array of objects where each row becomes an object with column headers as keys. Pretty-printed for readability.
Tab-Separated Values – similar to CSV but uses tabs instead of commas as delimiters. Useful when your data contains commas that shouldn't be treated as separators.
Format, validate, compare, and minify JSON data. Auto-fix common errors, generate TypeScript interfaces, and decode Base64/URL-encoded JSON.
Try JSON ToolsNeed to convert your CSV to JSON? Our CSV tool exports to JSON format, and the JSON formatter can help you beautify and validate the output.
Format JSON Output