CSV Merger

Join two CSV files by matching columns. Supports inner, left, and right joins. Free, private — all in your browser.

Merge result will appear here

About CSV Merger

Combine two CSV files by matching rows on a common column, just like a database JOIN. Perfect for merging customer data, combining exports, enriching datasets, and reconciling records from different sources.

Join Types

Inner join (matching rows only), left join (all rows from first file), or right join (all rows from second file). Works like SQL JOINs.

Auto Column Detection

Parses CSV headers automatically and populates column selectors. Click "Detect Columns" to refresh after changing CSV data.

Live Preview

See merged results instantly in an HTML table. Verify the join is correct before downloading the merged CSV file.

Private & Secure

CSV data processed locally in your browser. No uploads, no servers. Your data never leaves your device.

📋 Common Use Cases

Pre-Analysis Data Prep

Clean CSV and spreadsheet data before analysis. Standardize formats, remove duplicates, and fix inconsistent values that would skew results.

PII Redaction

Remove or mask personally identifiable information before sharing datasets with third parties or publishing open data. Comply with privacy regulations.

Text File Parsing

Convert unstructured text files into organized columns. Extract structured data from logs, reports, or exported text dumps.

Database Cleanup

Prepare data for database import by fixing malformed records, standardizing field formats, and removing invalid characters.

🪜 How to Use This Tool

  1. Load your data
    Paste raw text or upload a file. The tool auto-detects delimiters and structure in CSV, TSV, and fixed-width formats.
  2. Choose cleaning operations
    Select what to do — remove duplicates, trim whitespace, anonymize PII, split columns, or standardize formats.
  3. Preview changes
    Review a before/after comparison of your data. Adjust cleaning rules if needed before applying to the full dataset.
  4. Download cleaned data
    Export as CSV, JSON, or copy to clipboard. Original data is never uploaded — all cleaning happens locally.

📚 Related Guides

Frequently Asked Questions

Is this data tool free?▼
Yes. All data tools are completely free. No signup needed.
Is my data sent to a server?▼
No. All data processing happens in your browser. Your JSON, CSV, SQL, and text data never leaves your device.
Can these handle large files?▼
JSON formatter and CSV tools comfortably handle files up to ~10MB in browser. Performance depends on your device for larger datasets.