JSON Unflatten
Inverse of json-flatten. Take a flat object with dot-notation keys (a.b.c) and rebuild the nested JSON structure. Round-trips with json-flatten.
About JSON Unflatten
JSON Unflatten is the inverse of JSON Flatten: hand it a flat object with dot-notation keys like a.b.c and it rebuilds the full nested JSON structure. Use it to reconstruct hierarchical config from a flat key list, or to round-trip data you flattened for a spreadsheet back into real objects. It works entirely in your browser, with no upload.
- Category
- convert
- Input
- Accepts: application/json or text/plain.
- Output
- Outputs: application/json.
- Cost
- Free, runs in your browser
- Memory
- low
Common uses
- Rebuild nested config from a flat list of dot-notation keys edited in a spreadsheet
- Reconstruct a structured API payload from flattened CSV columns
- Turn flat KEY.SUBKEY environment-style entries back into a nested object
- Round-trip data through JSON Flatten and back without losing the hierarchy
- Assemble a deeply nested object by writing simple dotted keys instead of hand-nesting braces
- Convert a flat translation file (en.home.title) into the nested shape a framework expects
Frequently asked questions
How does it know where to nest?
It splits each key on the dots, so a.b.c becomes a nested object three levels deep.
Does it round-trip with JSON Flatten?
Yes. Flattening then unflattening (or vice versa) returns the original structure.
Are numeric keys turned into arrays?
Indexed dot keys reconstruct the nested shape they came from, mirroring how Flatten encoded them.
Is my data sent anywhere?
No. The whole operation runs locally in your browser.
What input format does it expect?
A flat JSON object (application/json or plain text) using dot-notation keys; it returns nested JSON.
Keywords
- json
- unflatten
- nest
- expand
- dot-notation
- structure