What this tool does
Appends a new column to the right of an existing CSV. The values you add are also supplied as CSV, including a header.
How to use it
- Paste the source CSV in the first box.
- Put the new column, header and values, in the second box.
- Run it and check the row counts line up.
Worked example
Appending c and 3 to a,b and 1,2 produces a,b,c and 1,2,3.
Frequently asked questions
- What if the row counts differ?
- The shorter side can end up with blanks, or rows may be truncated. Align the row counts before appending.
- Can I append several columns?
- Yes — supply a CSV with multiple columns in the second box, listing all the names in its header row.
What this tool does not cover
Input is processed in your browser. It appends by row position and does not join on a key.