JSON to CSV

json-to-csv · version 1.0.0 · JSON & JSONL · free, no key needed

Serialize string-valued JSON rows to CSV using explicit ordered columns.

Use when you need to: json to csv · convert json rows to csv · serialize json objects as csv.

Supported

• json to csv
• convert json rows to csv
• serialize json objects as csv

Not supported

• infer columns
• coerce values
• flatten nested json
• stream rows
• read files
• fetch urls

Behavior

• columns supplies the non-empty, unique header names and their output order.
• Every row must contain exactly those own keys with string values.
• Values are not coerced and nested values are rejected.
• Row order is retained and an empty rows array produces header-only CSV.
• Prototype-like column names are handled as ordinary own JSON keys.
• The first column name may not begin with U+FEFF because it is ambiguous with a CSV byte-order mark.

Input

• columns (array of string, required): min items 1; max items 256; each min length 1
• rows (array of object, required): max items 5000

Output

• string

Limits

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

Example

Request input:

{
  "columns": [
    "name",
    "note"
  ],
  "rows": [
    {
      "name": "Ada",
      "note": "hello, world"
    }
  ]
}

Response:

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

How to call it

MCP

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

{
  "id": "json-to-csv",
  "version": "1.0.0",
  "input": {
    "columns": [
      "name",
      "note"
    ],
    "rows": [
      {
        "name": "Ada",
        "note": "hello, world"
      }
    ]
  }
}

HTTP (no key)

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

The machine-readable contract is at /v1/tools/json-to-csv/versions/1.0.0.

CLI

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

Get the client at /clients/cli/.

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