Tool
Smart Merge CSV Files
Upload two CSV files. We analyse their schemas, detect the best merge key, warn you about risks, and produce a clean merged file — entirely in your browser.
Use our Intelligent AI merge with Pro →A
Drop File A
CSV — click to browse
B
Drop File B
CSV — click to browse
How Smart Merge thinks
Detects semantic column types: email, phone, ID, date, name, zip
Scores keys on value overlap — actual data, not just column names
Warns about many-to-many joins that could multiply your rows
Detects duplicate keys that signal relationship shape
Applies penalties for high null rates and low coverage
Shows matched vs unmatched row counts before you confirm
Executes the merge 100% locally — files never leave your browser
Left, inner, or full outer join — your choice