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CSV Constant Column Adder
Insert one named constant CSV column with exact text or a precedence-controlled UTF-8 file.
Pasted CSV, One UTF-8 CSV/TSV/text file, Optional UTF-8 constant text file
constant-column.csv, constant-column-report.json
Browser only
Runs locally in your browser. Your files, pasted content and generated output are not uploaded. Reset clears this tool’s working data.
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How to use this tool
- Enter the admitted input using CSV input, Input delimiter, New header, Constant value, Placement, Before position. A selected UTF-8 source file takes precedence over paste.
- Set New header and Constant value, or choose UTF-8 constant file (optional), which takes precedence even when empty. Set Placement and spreadsheet protection.
- Select Add constant column and download constant-column.csv, constant-column-report.json.
Examples
A new header constant with an empty constant appends an empty field to every data record.
Limitations
- 5 MiB CSV, 50,000 data rows, 500 output columns and 500,000 cells; 20 MiB combined artifacts and a 30-second processing limit.
- Header 1–1,000 UTF-16 units without CR/LF. Constant at most 1,000 scalar-valid UTF-16 units; optional file at most 4,096 bytes. Empty constant/file is valid.
- Strict unique nonempty output headers; no dataset merge, generated sequence, type inference or multiline-header support. Native paste normalizes line endings; use a file for original CR/CRLF.
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