Flatten JSON without leaving the browser. JSON Flatten flattens nested JSON into dot-notation keys and unflattens it back again — useful when you need to collapse a nested object into dot-notation keys for spreadsheets or configs between two other steps of a debugging session. Everything runs inside your browser, so the file never touches a server, which matters when the payload contains tokens, customer records or anything else you would not paste into an unknown server.
How to
Four steps, no account, nothing to install.
Add the object you want to flatten.
Dots suit config files; other separators suit spreadsheet headers.
Switch direction whenever you need the original shape back.
Overview
JSON is the default interchange format of the modern web. It represents data as nested objects and arrays of strings, numbers, booleans and null, and every mainstream language ships a parser for it. Its grammar is deliberately tiny — no comments, no dates, no trailing commas — which makes it fast to parse but strict about syntax.
Paste nested JSON — Add the object you want to flatten. Choose a delimiter — Dots suit config files; other separators suit spreadsheet headers. Flatten or unflatten — Switch direction whenever you need the original shape back. The whole loop is designed to be repeatable: change the input, read the new result, no re-submit step in between.
The failures people hit are predictable: No comments; No native date or binary type; Strict syntax breaks on trailing commas. Each of those shows up as a specific, fixable symptom rather than a vague error, which is exactly what this tool surfaces.
API request and response bodies, Configuration files, Log records (NDJSON) — these are the contexts where JSON shows up, and this page is the fast path between "I have a blob of input" and "I understand what it contains". Keep the tab open next to your editor and your terminal.
Features
Configurable delimiter
Round-trips without losing data
Array index notation
Copy or download the result
Reference
| Property | Value |
|---|---|
| Format | JSON (JavaScript Object Notation) |
| Extension | .json |
| MIME type | application/json |
| Human readable | Yes |
| Typical use | API request and response bodies |
Examples
Copy the raw payload out of the network tab, drop it in here, and read the result immediately — no curl round trip, no scratch file.
Paste the snippet from the diff to confirm what it evaluates to before approving the change.
Because processing is local, real payloads with real identifiers can be inspected without violating a data-handling policy.
Benefits
FAQ
1. Paste nested JSON: Add the object you want to flatten. 2. Choose a delimiter: Dots suit config files; other separators suit spreadsheet headers. 3. Flatten or unflatten: Switch direction whenever you need the original shape back.
No. Everything runs inside your browser, so the file never touches a server — safe for tokens, staging payloads and customer data.
Yes, with no account, no rate limit and no paid tier.
A lightweight, text-based format for structured data built from objects, arrays and primitives. It represents data as nested objects and arrays of strings, numbers, booleans and null, and every mainstream language ships a parser for it
No comments; No native date or binary type; Strict syntax breaks on trailing commas; Verbose for large flat tables.
Once the page has loaded, yes — the processing needs no network access.
Tools
Explore
Learn