JSON ↔ CSV Converter

CSV (Comma-Separated Values) is a flat, tabular format — rows and columns, no nesting — which makes it the format spreadsheets, databases, and data-analysis tools expect. JSON, by contrast, is naturally nested: objects inside objects, arrays of objects, arrays inside arrays. Converting between them means either flattening JSON's nesting into columns, or folding CSV's flat columns back into nested JSON.

This tool flattens nested keys using dot notation — a "tags" array becomes "tags.0", "tags.1", and so on, and a nested "meta.featured" field becomes its own column. Converting back reverses the process, rebuilding the nested structure from those dotted column names. Everything runs locally in your browser; nothing you paste is sent anywhere.

• •JSON → CSV expects a top-level array of objects (a single object is treated as one row). Deeply nested or highly irregular JSON will produce very wide, sparse CSVs — flatten your data model first if that's not what you want.
• •An empty CSV cell always becomes a missing key in the JSON output, not an empty string or null — CSV has no way to tell those three apart. If that distinction matters, encode it explicitly (e.g. a literal word) before converting.
• •Values with leading zeros (zip codes, phone extensions) are intentionally kept as strings, not numbers — converting "07001" to a number would silently drop the leading zero.
• •If a cell's value itself contains a comma, quote, or line break, wrap it in double quotes when hand-editing CSV — this tool does that automatically on JSON → CSV, but it matters if you're pasting CSV from elsewhere.