CSV select columns

csv-select-columns · version 1.0.0 · CSV & tables · free, no key needed

Select and reorder exact named columns from a complete CSV document.

Use when you need to: csv select columns · select csv columns · reorder csv columns.

Supported

• csv select columns
• select csv columns
• reorder csv columns
• project csv columns

Not supported

• rename columns
• match columns fuzzily
• infer types
• filter rows
• read files
• fetch urls

Behavior

• columns must name unique existing headers exactly and determine output order.
• Cell strings, data-row order, and quoted CSV content are preserved semantically.
• No trimming, type coercion, renaming, or fuzzy column matching is performed.
• Header-only input is supported; an empty document is rejected because it has no header.
• The first selected column name may not begin with U+FEFF because it is ambiguous with a CSV byte-order mark.

Input

• csv (string, required): max length 256000
• columns (array of string, required): min items 1; max items 256; each min length 1

Output

• string

Limits

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

Example

Request input:

{
  "csv": "name,city,note\nAda,London,\"hello, world\"\n",
  "columns": [
    "note",
    "name"
  ]
}

Response:

{
  "result": "note,name\n\"hello, world\",Ada\n"
}

How to call it

MCP

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

{
  "id": "csv-select-columns",
  "version": "1.0.0",
  "input": {
    "csv": "name,city,note\nAda,London,\"hello, world\"\n",
    "columns": [
      "note",
      "name"
    ]
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/csv-select-columns/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"csv":"name,city,note\nAda,London,\"hello, world\"\n","columns":["note","name"]}'

The machine-readable contract is at /v1/tools/csv-select-columns/versions/1.0.0.

CLI

node cli.mjs run csv-select-columns 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• CSV dedupe: Remove duplicate CSV data rows while preserving the first occurrence.
• CSV drop columns: Drop named CSV columns and keep the remaining columns in original header order.
• CSV fill defaults: Replace empty cells in named CSV columns with exact default strings.
• CSV group count: Count CSV rows by exact named-column tuples in first-seen order.
• CSV merge columns: Join named CSV columns with an exact separator into one column.
• CSV rename columns: Rename CSV headers by an exact from/to mapping, preserving row cells and column order.