About the JSON ↔ CSV Converter

Last updated 2026-07-11

What this tool is

json2csv is a free, no-signup converter between JSON and CSV. Paste an array of objects, a single object, or deeply nested JSON and it flattens the structure into dot-notation columns and produces a CSV that opens cleanly in Excel and Google Sheets. Switch the direction and it parses CSV back into JSON with optional type inference and unflattening. It is aimed at developers and data folks who just need a quick, reliable transform.

How it works

• Nested objects are flattened to dot.notation columns at unlimited depth; the column set is the union of all record keys.
• Arrays can be laid out as indexed columns, joined into one cell, kept as a JSON string, or exploded into multiple rows (cartesian product across array fields).
• CSV serialization and parsing follow RFC 4180: quoting on delimiter/quote/newline, doubled quotes, and a default \r\n line ending.
• CSV → JSON auto-detects the delimiter, infers types with an exact round-trip check (so IDs are not corrupted), and can rebuild nested objects from dot-notation headers.

Privacy

There is no backend. Your JSON and CSV are processed entirely in your browser with JavaScript and are never uploaded, logged, or stored on a server. There is no account and no tracking of your data. Your option settings (delimiter, flatten, and so on — not the data) can optionally be saved to your browser's localStorage and encoded into a shareable ?s= link. Once the page has loaded, the converter works offline.

Limitations

• Processing happens in memory, so very large inputs (hundreds of MB) may be slow or exceed browser limits.
• Explode over several large array fields produces a cartesian product and can multiply row counts quickly.
• Type inference is a heuristic; disable it when you need every value kept as a string.

Who runs it

This tool is built and operated by bal.pe.kr, a one-person micro-SaaS portfolio of free, static, privacy-friendly web utilities. The goal is to make small, dependable tools that do one job well.

• Operator: bal.pe.kr (independent micro-SaaS)
• Contact: comsamo84@gmail.com
• More tools: bal.pe.kr tools

Standards referenced

• RFC 4180 — Common Format and MIME Type for CSV Files
• JSON (ECMA-404)