API Payload Size Analyzer
Measure UTF-8 payload size and actual local gzip compression.
CSV Duplicate Key Finder
Find duplicate values in a selected CSV key column.
Processed locally in your browser.
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How to use CSV Duplicate Key Finder
- Choose Example to see valid input, or enter your own data.
- Run the tool and review the result. Invalid inputs show a helpful error.
- Copy or download the output, or use Reset to clear the workspace.
Practical example
id,name 1,Ada 1,Sam
Common question
What should I know before using this tool?
Reports data row numbers, starting at 2 after the header. Matching is case-sensitive.
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