Calculator
What the JSON Flattener does
JSON Flattener: calculates Status and Result from JSON, Direction and Array index style. Example: direction Flatten (nested → dotted keys) and array index style roles.0 gives status Flattened to 6 keys.
Enter JSON, Direction and Array index style and the JSON Flattener reports Status and Result. Edit a field and the answer updates in place.
Typical users are developers debugging a payload. Spotting a malformed field is far quicker when the structure is laid out clearly.
Because it is all local, the tool is as fast as your device and as private as your own notes.
The meaning of each field, the formula in use, and a worked example that starts from the default inputs are all further down.
What do the JSON Flattener fields mean?
The JSON Flattener uses 3 inputs. You can work from the defaults, or clear them and start fresh, both work.
| Field | What to enter | Default |
|---|---|---|
| JSON | paste or type any amount of text | { "user": { "id": 1, "name": "Ada", "roles": ["admin", "dev"] }, "meta": { "page": 2, "tags": [] } } |
| Direction | choose from Flatten (nested → dotted keys) or Unflatten (dotted keys → nested) | Flatten (nested → dotted keys) |
| Array index style | choose from roles.0 or roles[0] | roles.0 |
How does the JSON Flattener work?
Each output is derived from the inputs above in a single pass; there is no hidden state carried between runs, so the same inputs always give the same calculation.
The guard clauses run before the formula does, which is why mistakes surface next to the field.
Worked example
These are the values the JSON Flattener loads by default, and the result it produces from them. Here is the calculation as it stands the moment the page loads.
| JSON | { "user": { "id": 1, "name": "Ada", "roles": ["admin", … |
|---|---|
| Direction | Flatten (nested → dotted keys) |
| Array index style | roles.0 |
| Status | Flattened to 6 keys |
|---|---|
| Result | { "user.id": 1, "user.name": "Ada", "user.roles.0": "admin", "user.roles.1": "dev", "meta.page": 2… |
Read next: JSON Formatting: The Rules People Get Wrong
How to use it
- Paste your content into JSON.
- Pick a value for Direction: the options are Flatten (nested → dotted keys) or Unflatten (dotted keys → nested).
- Pick a value for Array index style: the options are roles.0 or roles[0].
- The result appears as you type. There is no button to press.
- You get Status and Result back.
- Copy Link is the quickest way to send the exact scenario to someone else.
What this tool does not do
- Output follows the common convention for this format; a specific toolchain may have its own house style.
- Processing happens in your browser, so very large inputs are bounded by available memory.
- Nothing is saved between visits, so keep your own record of anything you need again.
Frequently asked questions
JSON, Direction and Array index style. That is the whole form. Nothing starts empty, meaning you can explore the calculation before committing to real figures.
With the values loaded when the page opens, status comes out as Flattened to 6 keys. Any edit re-runs the calculation, so there is no stale number on screen.
Nothing is logged. The tool is client-side code; your data stays where you entered it.
Nothing at all. There is no registration, no paywall and no per-use quota.
Reliable for the case described. Where more than one convention exists, the method section says which one is used.