Append TSV Column

Tab-separated values (TSV) remain a dominant interchange format in bioinformatics pipelines, database exports, and spreadsheet workflows. Appending a column manually in a text editor invites misalignment errors: a single missing \t character shifts every downstream field, corrupting imports into SQL tables or statistical software. This tool parses your TSV structure, validates row consistency, and appends a new column with either a uniform fill value, per-row mapped values, or an index-based sequence. It handles edge cases including quoted fields, trailing newlines, and mixed \r\n line endings. The output preserves your original delimiter structure exactly. Note: this tool assumes strictly tab-delimited input. If your data uses commas or semicolons, convert delimiters first.

The append operation constructs each output row by concatenating the original row with a tab character and the new cell value:

In Fill Mode, value_i = C (constant) for all i ∈ [0, n). In Map Mode, each value_i is drawn from a user-supplied list of n values. If the list is shorter than the row count, remaining cells receive an empty string. In Index Mode, value_i = i + offset, where offset is a user-defined start index (default 1).

Where row_in = original row string, n = total number of data rows, C = constant fill value, i = zero-based row index, offset = starting number for index mode.