CSV Merger
Combine multiple CSV files into one. Stack rows or add columns side-by-side.
How it works: Upload 2+ CSV files → choose merge mode (Vertical to stack rows, Horizontal to add columns) → download merged file. Privacy first: Everything happens in your browser — your data never leaves your device.
No file? Try it instantly with synthetic sample data.
Benchmark Performance
Real-world tested, production-ready
223K rows/sec
15M+ rows
Multiple files
View full benchmark →