Browser Tool
Free CSV Merger
Stop wrestling with VLOOKUPs that crash Excel. Join two CSV files instantly in your browser.100% Client-Side. Secure. Fast.
Primary File (Left)
Drag & drop or click to browse
Lookup File (Right)
Drag & drop or click to browse
When to use
Simple File Joins
This tool is perfect for quick, one-off joins where keys are exact and headers match. Ideally used for ad-hoc file consolidation or VLOOKUP replacements.
- Exact match VLOOKUPs
- Simple column appending
- One-off report merging
Need fuzzy matching or validation?
Implementation teams often face messier realities. Inconsistent headers, fuzzy matches, and the need to validate data during the merge require a robust transformation layer.
Client-Side Processing ArchitectureSecure
Your data never leaves your device. All processing happens locally in your browser's memory via WebAssembly/JavaScript. This ensures complete data sovereignty and compliance with GDPR, HIPAA, and SOC2 standards as no files are uploaded to our servers.
Frequently Asked Questions
How does the merge work?▼
It performs a SQL-style 'Join'. You upload two files (Left and Right) and select a common column (the Key) in each. The tool matches rows based on that Key and combines their data.
What is a Left Join vs Inner Join?▼
A Left Join keeps all rows from your first file, even if no match is found in the second (filling blanks). An Inner Join only keeps rows that exist in BOTH files.
Can I automate this for monthly reports?▼
For recurring tasks, our main platform DataFlowMapper allows you to save this join logic as a reusable template. You can then automate the entire pipeline, including fuzzy matching and validation, without manual file uploads.
Is this faster than Excel VLOOKUP?▼
For large datasets, yes. Excel often crashes with thousands of VLOOKUP formulas. Our engine processes the join in memory efficiently, handling tens of thousands of rows in seconds.
The visual data transformation platform that lets implementation teams deliver faster, without writing code.
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