JSON ⇄ CSV Converter
Two-way conversion with nested flattening, JSONL, auto-delimiters and smart type inference.
A converter that handles real-world data, not just textbook examples: nested objects flatten predictably, arrays convert three different ways depending on what your spreadsheet needs, JSONL streams are recognized automatically, and the CSV parser survives quoted commas, embedded newlines and regional semicolon files. Conversion is live as you type, entirely in your browser.
Frequently Asked Questions
How does it handle nested JSON objects?
Nested structures flatten into dotted column names: {"user":{"name":"Jane"}} becomes a user.name column (the separator is configurable). Arrays have three modes — keep as JSON string, join values with |, or explode into indexed columns like tags.0, tags.1.
Does it support JSONL (JSON Lines)?
Yes, automatically — paste one JSON object per line (the standard log/export format from many APIs and data tools) and it is detected and converted without any setting.
What does the Excel BOM option do?
Excel only displays UTF-8 characters (Hindi, Arabic, emojis, accents) correctly when the CSV starts with a byte-order mark. Tick it when the file is destined for Excel; leave it off for programming use.
How smart is the CSV → JSON direction?
The delimiter is auto-detected (comma, semicolon, tab or pipe), quoted fields with embedded commas and newlines parse correctly per RFC 4180, and optional type inference converts "42" → 42, "true" → true and empty cells → null — while protecting things like phone numbers with leading zeros.
Is there a file size limit?
Everything runs in your browser memory, so multi-megabyte files convert fine on any modern machine. Nothing uploads anywhere — which also means your data never leaves your device.