← CSV and JSON converter

Convert CSV to JSON in Node.js

Convert CSV to JSON or JSON to CSV. Handles quoted fields, line breaks inside cells, semicolon and tab files, BOMs and nested JSON. Here is the whole call in Node.js, with the output it produced when we ran it.

Before you start

• An API key. Create a free account; it comes with free tokens every month. Put the key in an environment variable so it stays out of your code: export BLOODWEB_KEY=your_key
• Node.js 18 or later. Nothing to install: fetch, FormData and Blob are built in. Save the file with the .mjs ending so await works at the top level.
• The input file in the same folder: orders.csv. Use your own; that is the name the code expects.

The code

Save it as csv-json.mjs and run node csv-json.mjs.

// Node.js 18 or later: fetch, FormData and Blob are built in.
import { readFile } from "node:fs/promises";

const form = new FormData();
form.append("file", new Blob([await readFile("orders.csv")]), "orders.csv");

const res = await fetch("https://bloodweb.net/api/v1/csv-json", {
  method: "POST",
  headers: { Authorization: `Bearer ${process.env.BLOODWEB_KEY}` },
  body: form,
});
if (!res.ok) throw new Error(`${res.status}: ${(await res.json()).error.message}`);
console.log(await res.json());

What you get

Tested 19 October 2026: this exact code ran against our test copy of the API, which runs the same service code as bloodweb.net, and produced this.

The API answers with JSON:

[
    {
        "order": "1001",
        "customer": "Avery Chen",
        "country": "AU",
        "total": "62.00"
    },
    {
        "order": "1002",
        "customer": "Sam Patel",
        "country": "US",
        "total": "44.50"
    },
    {
        "order": "1003",
        "customer": "Jo Smith",
        "country": "NZ",
        "total": "90.00"
    }
]

Change the call

Every option the CSV and JSON converter takes. Add or change them the same way as the ones in the code.

• text: The CSV or JSON to convert.
• to: Output. Defaults to the opposite of what was sent. One of: json, csv.
• delimiter: CSV delimiter. auto detects it when reading; writing defaults to comma. One of: auto, comma, semicolon, tab, pipe.
• header: CSV to JSON: the first row holds column names, giving an array of objects. Off gives an array of arrays.
• types: CSV to JSON: turn numbers, true/false and empty cells into JSON numbers, booleans and null. Off keeps every value as text.
• excel_safe: JSON to CSV: prefix cells starting with = + - @ with an apostrophe, so spreadsheets do not run them as formulas.
• bom: JSON to CSV: start with a UTF-8 byte order mark, which Excel needs to show accents correctly.

If it fails

A failed call is not charged. The answer is JSON with an error object; the code above prints its message. The usual ones:

• 401 missing_key or invalid_key: BLOODWEB_KEY is not set in the shell that runs the code, or the key was revoked.
• 415 unsupported_type: the file is not a type this service reads. The type is read from the file itself, so renaming a file does not change it.
• 413 file_too_large: the file is over the limit on the service page.
• 402 insufficient_tokens: the balance does not cover the call. Top up in the dashboard.
• 429 rate_limited: too many calls at once. Wait the seconds in the Retry-After header and send it again.

Every code and its fix is in the docs.

Next

• The CSV and JSON converter page: every option, the limits, and Try it now in your browser.
• Getting started: keys, errors and rate limits for all the services.