JSON Flatten Tool

Paste any JSON object or array. The tool walks every leaf value recursively and builds a flat Record<string, unknown> where each key is the full path joined by your delimiter. Arrays are handled according to your strategy:

• Expand creates indexed paths like tags[0] or tags.0.
• Preserve keeps the array as a leaf value at its parent key (e.g., "tags": ["dev", "admin"]).

Empty arrays in expand mode produce no keys. Nested objects inside arrays continue to flatten correctly (items[0].name).

Unflatten Mode

Paste a flat JSON object. The parser splits each key by the delimiter. Numeric segments are interpreted as array indices when using dot-style (tags.0.name); bracket segments (tags[0]) are parsed as property + index pairs. The tool rebuilds nested objects and arrays, throwing clear errors if it detects ambiguous paths (e.g., a key is both a leaf and a parent).

Options

• Delimiter: any string (., _, /, -, or custom).
• Array index style: bracket (items[0]) or dot (items.0).
• Array strategy: expand into indexed keys or preserve arrays intact.
• Output format: pretty-printed or compact JSON.

Results update instantly as you type.