JSON formatter and validator

Format (pretty-print) or minify JSON and validate it against RFC 8259, with the line and column of any syntax error explained in plain words.

Mis à jour Exemples vérifiés : 6

Plus d’options
Essayer
Check
Valid JSON
Check: Valid JSON
Formatted JSON
{ "name": "CalcOpenly", "version": "1.0.0", "precision": 50, "domains": [ "math", "finance", "programming" ], "offline": true, "license": null }
Keys
6
Nesting depth
2
Values
10
Input size
127bytes
Output size
170bytes

The JSON is valid: 10 values with 6 keys, nested 2 levels deep. Pretty-printing takes it from 127 to 170 bytes.

Formatted JSON

{
  "name": "CalcOpenly",
  "version": "1.0.0",
  "precision": 50,
  "domains": [
    "math",
    "finance",
    "programming"
  ],
  "offline": true,
  "license": null
}
Value types Lignes : 6
TypeCount
Objects1
Arrays1
Strings5
Numbers1
Booleans1
Nulls1
Comment le calcul est effectué S
  1. Parse with the RFC 8259 grammar

    Valid JSON: 1 objects, 1 arrays, 5 strings, 1 numbers, 1 booleans, 1 nulls.

  2. Mesures

    6 keys in total; the deepest value sits 2 levels down.

  3. Pretty-print

    One member or item per line, indented 2 spaces per level.

    Strings and numbers are copied exactly as written, so escapes and number formats are unchanged.

À propos de JSON formatter and validator

The validator parses the text with the RFC 8259 grammar: objects, arrays, double-quoted strings, numbers, true, false and null, and nothing else. If parsing succeeds, it prints the same values back, either with one member per line and 2 spaces, 4 spaces or a tab per level, or minified with every space outside strings removed. If it fails, it reports the line and column where the grammar broke and what it expected there.

Developers use it to read API responses and config files and to shrink payloads. The default object has 6 keys and 10 values nested 2 levels deep, and pretty-printing it with 2 spaces grows it from 125 to 168 bytes.

Strings and numbers are copied exactly as written, so escapes survive and a large integer such as 12345678901234567890123 keeps every digit.

Exemples détaillés

Pretty-print with 2 spaces

JSON
{"name":"CalcOpenly","tags":["math","finance"],"ok":true,"none":null}
Sortie
Pretty-print
Indent with
2 spaces
Check
Valid JSON
Formatted JSON
{ "name": "CalcOpenly", "tags": [ "math", "finance" ], "ok": true, "none": null }
Keys
4
Nesting depth
2
Values
7

Source de vérification : Python 3.8: json.dumps(json.loads(s), indent=2, ensure_ascii=False); value count by walking json.loads(s)

Minify

JSON
{ "a": [1, 2, {"b": "x y"}], "c": false }
Sortie
Minify
Formatted JSON
{"a":[1,2,{"b":"x y"}],"c":false}
Input size
45 bytes
Output size
33 bytes
Nesting depth
3

Source de vérification : Python 3.8: json.dumps(json.loads(s), separators=(',', ':')); len(s.encode()) = 45, output 33 bytes

A bare number is valid JSON (edge)

JSON
42
Sortie
Pretty-print
Indent with
2 spaces
Formatted JSON
42
Keys
0
Nesting depth
0
Values
1

Source de vérification : RFC 8259 §2 (any value may be the top-level text); Python 3.8 json.dumps(json.loads(' 42 '), indent=2) = '42'

Empty containers stay on one line

JSON
{"a":[],"b":{}}
Sortie
Pretty-print
Indent with
4 spaces
Formatted JSON
{ "a": [], "b": {} }
Keys
2

Source de vérification : Python 3.8: json.dumps(json.loads(s), indent=4)

Questions

What are the most common JSON syntax errors?

Trailing commas, single quotes and unquoted keys cause most failures, because JSON requires double quotes around every string and key and allows no comma after the last item. Comments, NaN, Infinity and hex numbers are also invalid under RFC 8259, although JavaScript accepts some of them in code. The error message here gives the line and column, so you can go straight to the character that broke the parse.

Does JSON allow comments?

No. RFC 8259 and ECMA-404 define no comment syntax, so a standard parser rejects // and /* */. Douglas Crockford removed comments from the format early on because people were using them to hold parser directives. Config files that need comments use JSON5 or JSONC, the format of VS Code's settings.json, and this validator reports those files as invalid JSON.

How large can a JSON number be?

RFC 8259 sets no limit, but it warns that only integers between −(2^53 − 1) and 2^53 − 1 = 9,007,199,254,740,991 are sure to interoperate, since many parsers use IEEE 754 doubles. This tool copies numbers digit for digit, but JavaScript's JSON.parse turns 12345678901234567890123 into 1.2345678901234568e22, so send large IDs as strings.

Are duplicate keys allowed in JSON?

RFC 8259 says the names within an object SHOULD be unique, so duplicates are legal but unreliable: JavaScript's JSON.parse and Python's json module keep only the last value, while other parsers keep the first or reject the document. This validator accepts them but warns with the line and column of the object, so you can remove the duplicate before another system reads it differently.

What is the difference between pretty-printing and minifying JSON?

Pretty-printing puts each member on its own line with 2 or 4 spaces or a tab per level, which makes the data easy to read and diff; minifying removes every space and line break outside strings for transfer. Both describe exactly the same data. The default example grows from 125 to 168 bytes when pretty-printed, and the minify example shrinks from 45 to 33 bytes.

Quelle est la précision de « JSON formatter and validator » ?

La précision dépend de vos données et des hypothèses de la méthode. Le calcul décimal utilise 50 chiffres significatifs, mais les estimations, méthodes numériques et données sources peuvent être moins précises ; l’arrondi affiché ne supprime pas ces limites. Exemples résolus vérifiés à partir de sources indépendantes : 6. Par exemple, « Pretty-print with 2 spaces » est vérifié à l’aide de Python 3.8: json.dumps(json.loads(s), indent=2, ensure_ascii=False); value count by walking json.loads(s).

D’où vient cette méthode ?

RFC 8259 — The JavaScript Object Notation (JSON) Data Interchange Format; ECMA-404 — The JSON data interchange syntax, 2nd edition.

À propos de ce calculateur

Sources

  1. RFC 8259 — The JavaScript Object Notation (JSON) Data Interchange Format
  2. ECMA-404 — The JSON data interchange syntax, 2nd edition

Vérifié avec les références

Ce calculateur comprend 6 exemples résolus dont les réponses proviennent de sources indépendantes. Ils font partie de la suite de tests et peuvent aussi être exécutés ici.

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