CSV add row number

csv-add-row-number · version 1.0.0 · CSV & tables · free, no key needed

Prepend a 1-based row_number column of canonical integer strings.

Use when you need to: csv add row number · csv row numbers · enumerate csv rows.

Supported

• csv add row number
• csv row numbers
• enumerate csv rows

Not supported

• 0-based
• gap fill
• sort

Behavior

• Reuse baseline CSV parser/stringifier and limits.
• column_name defaults to row_number. Must be a non-empty string within header byte limit.
• If column_name already exists, reject.
• Insert the new column at index 0. Values are "1", "2", ... canonical integers.
• Empty document -> csv "". Header-only -> new header plus original headers and zero data rows.
• Adding the column must not exceed max_columns.

Input

• csv (string, required): max length 256000
• column_name (string, optional): min length 1; max length 256

Output

• csv (string, required)
• rows_in (integer, required)

Limits

• max input bytes: 256000
• max data rows: 5000
• max columns: 256
• max header name bytes: 256

Example

Request input:

{
  "csv": "k\na\nb\n"
}

Response:

{
  "result": {
    "csv": "row_number,k\n1,a\n2,b\n",
    "rows_in": 2
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "csv-add-row-number",
  "version": "1.0.0",
  "input": {
    "csv": "k\na\nb\n"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/csv-add-row-number/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"csv":"k\na\nb\n"}'

The machine-readable contract is at /v1/tools/csv-add-row-number/versions/1.0.0.

CLI

node cli.mjs run csv-add-row-number 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• CSV row diff: Compare two CSV documents with identical headers by unique key tuples and report added, removed, and changed rows.
• CSV slice rows: Take a contiguous window of CSV data rows by offset and limit, keeping the header.
• CSV anti join: Keep left CSV rows whose exact key tuples do not appear in the right document.
• CSV concat: Concatenate CSV documents that share identical headers, preserving document and row order.
• CSV dedupe: Remove duplicate CSV data rows while preserving the first occurrence.
• CSV group count: Count CSV rows by exact named-column tuples in first-seen order.