---
title: "CSV ↔ JSON converter"
canonical: "https://devtools.nicxon.tech/tools/csv-json/"
source: "https://devtools.nicxon.tech/tools/csv-json/"
generator: devtools.nicxon.tech
---

# CSV ↔ JSON converter

> Turn CSV into an array of objects and back, with delimiter and header control.

## What this does

CSV → JSON reads delimited text and produces either an array of objects
 (when the first row is a header) or an array of arrays (when it isn't).
 JSON → CSV takes an array and writes one row per element, with a header row
 derived from the union of all object keys. Parsing and serialization are
 handled by [PapaParse](https://www.papaparse.com/), which
 implements RFC 4180 quoting rules and handles quoted newlines, escaped
 quotes, and ragged rows.

Everything runs in your browser, so a customer export, a finance report, or
 a user list can be reshaped here without uploading it anywhere.

## When you'd use it

- Turning a spreadsheet export into JSON to seed a database or a test fixture.
- Converting an API's JSON array into CSV to open in a spreadsheet or hand to a non-technical colleague.
- Inspecting exactly how a CSV parses — where the column breaks land, what types are inferred — before writing code against it.
- Changing the delimiter of a file (for example semicolon-separated European CSV to comma-separated).

## Worked example

Input CSV, with "First row is header" and "Infer numbers & booleans" both on:

```
sku,name,price,in_stock
A-100,Widget,9.99,true
A-101,Gadget,14.5,false
```

Output JSON:

```
[
  { "sku": "A-100", "name": "Widget", "price": 9.99, "in_stock": true },
  { "sku": "A-101", "name": "Gadget", "price": 14.5, "in_stock": false }
]
```

Note that `sku` stays a string because it isn't numeric, while
 `price` becomes a number and `in_stock` becomes a
 boolean. Convert that JSON back with direction JSON → CSV and you get the
 original file, with a `
` after each row.

## Limits and gotchas

- **Type inference is heuristic.** It's convenient but lossy — turn it off whenever the exact text of a field matters.
- **Nested data doesn't survive JSON → CSV.** Flatten objects and arrays into scalar columns first.
- **Inconsistent columns.** If some rows have more fields than the header, the extras land under numeric keys; if fewer, missing keys are empty strings.
- **Big files.** Parsing is done in one pass in memory. Multi-hundred-megabyte files may exhaust the tab's memory.
- **Excel quirks.** A leading `=` in a cell is data here, not a formula; a UTF-8 BOM at the start of the file is stripped on parse.

## How to use

- **Choose a direction** — CSV → JSON to parse a spreadsheet export, or JSON → CSV to flatten an array of records.
- **Set the delimiter** — Leave it on Auto for most files, or pick comma, semicolon, tab, or pipe if auto-detection guesses wrong.
- **Set header and typing options** — For CSV → JSON, decide whether the first row is a header and whether numbers and booleans should be inferred.
- **Read and copy** — The converted output appears on the right with a row count and the detected delimiter. Copy it out.

## Frequently asked questions

### Why are my leading zeros gone (007 became 7)?

That happens when "Infer numbers & booleans" is on: 007 is read as the number 7. Zip codes, product codes, and phone numbers should stay text — turn that option off, or the value will lose its formatting. With inference off, every field is kept as a string.

### My file has commas inside quoted fields and the columns are misaligned.

A properly quoted CSV ("Smith, John",42) parses correctly here. Misalignment usually means the quoting is inconsistent — an unescaped quote inside a field, or a mix of quoted and unquoted rows. The error message names the row number; check that row for a stray ".

### JSON → CSV produced [object Object] in a cell.

CSV is flat: one value per cell. If a record contains a nested object or array, there is no correct way to put it in a single cell, so it is stringified. Flatten nested fields first (for example address.city as its own column) before converting.

### Which line endings and encoding does the output use?

Output CSV uses \r\n line endings, which is what the CSV specification (RFC 4180) and Excel expect. Text is UTF-8. If a downstream tool needs \n only, convert the line endings after copying.

---
*Source: [https://devtools.nicxon.tech/tools/csv-json/](https://devtools.nicxon.tech/tools/csv-json/) — generated by devtools.nicxon.tech.*