JSON Parser Online

Paste JSON and parse it

The page parses as you type, with the browser's own JSON.parse. Valid input shows a summary (the top-level type and how many objects, keys, arrays, array items, strings, numbers, booleans and nulls it holds, and the nesting depth) and a tree with each value's type. Switch to Text for the indented JSON. Invalid input shows the first error with its line and column and the line itself with a caret under the spot. Repair and view runs the same engine as the JSON repair tool and parses the result. Empty input shows nothing.

What a JSON parser does

Parsing turns text into values. The parser reads one character at a time and either builds the objects, arrays and scalars the text describes or stops at the first character the grammar does not allow. That is a syntax check only. Whether the data has the fields and types your program expects is a separate question, answered by a JSON Schema; the schema generator writes one from a sample.

The value types a parser returns

RFC 8259 defines four primitive types and two structured types:

• object — {"name": value, …}, names are strings
• array — [value, …], ordered
• string — "text" in double quotes
• number — -12.5e3; no leading zeros, no NaN or Infinity
• boolean — true or false
• null

A JSON text can be any one of these at the top level, so "hello" and 42 are valid JSON documents. Try them in the box: the summary shows the top-level type.

Why parsing fails

These are the messages this page reports for the usual faults, and what the repair step returns:

The leading-zero row shows that repair can guess: 012 becomes the string "012". Check repaired output before you rely on it. The validator gives the same yes/no answer without the tree.

Parse JSON in code

JavaScript has JSON.parse; Python has json.loads. Both throw on invalid input:

// Node.js 24
JSON.parse('{"a": 1,}')
// SyntaxError: Expected double-quoted property name in JSON at position 8 (line 1 column 9)

# Python 3.12
import json
json.loads('{"a": 1,}')
# json.decoder.JSONDecodeError: Expecting property name enclosed in double quotes: line 1 column 9 (char 8)

Two behaviours differ from what you might expect. With a repeated key, both keep the last value: {"a":1,"a":2} parses to {"a": 2}; RFC 8259 says names should be unique and leaves duplicates to the implementation. Large integers differ: JavaScript reads 12345678901234567890 as 12345678901234567000 (64-bit floating point), while Python keeps the exact integer. RFC 8259 notes that integers beyond 2⁵³−1 are not reliably exchanged. This page uses the browser's parser, so it shows the JavaScript result.

After parsing: format, query, compare, convert

• Format or minify the text.
• Query it with JSONPath.
• Compare two documents.
• Generate TypeScript types or a JSON Schema.
• Do all of it in JSON Studio. Unknown terms are in the glossary; the repair engine has an HTTP API.

Privacy and limits

The parser runs in your browser and does not send your JSON anywhere. Files up to 50 MB open; larger ones are refused with a message. In desktop Chrome a 1.7 MB file showed as a tree in about half a second, a 17 MB file in about 1.2 seconds and a 42 MB file in about 2 seconds. Text over 1 MB is kept out of the input box, and the Text view draws the first 1 MB of indented text (Copy still copies all of it). Phones and older computers are slower.

Frequently asked questions