Validator Free Tool

JSON Validator & Formatter

Validate and format JSON config files for game servers. Fix common errors like trailing commas, missing quotes, and syntax issues instantly.

Published Jan 14, 2026

Supported extensions: .json

How to Use This Tool

  1. Paste your JSON into the input area above
  2. Click Validate & Format to check for errors
  3. If valid, the formatted output appears with proper indentation
  4. Copy or download the cleaned-up JSON file

Enable “Validate as I type” for real-time feedback while editing.

Common JSON Errors in Game Servers

1. Trailing Commas (The #1 Mistake)

JSON does not allow a comma after the last item:

// ❌ WRONG - trailing comma
{
  "name": "My Server",
  "port": 25565,
}

// ✅ CORRECT - no trailing comma
{
  "name": "My Server",
  "port": 25565
}

Silent Config Reset

Many game servers (Enshrouded, Sons of the Forest, Minecraft) will silently overwrite your config with defaults if JSON is invalid. Always validate before uploading!

2. Single Quotes Instead of Double Quotes

JSON requires double quotes for strings:

// ❌ WRONG - single quotes
{'name': 'My Server'}

// ✅ CORRECT - double quotes
{"name": "My Server"}

3. Missing Commas Between Properties

Each property must be separated by a comma:

// ❌ WRONG - missing comma
{
  "name": "Server"
  "port": 25565
}

// ✅ CORRECT
{
  "name": "Server",
  "port": 25565
}

4. Comments in JSON

Standard JSON does not support comments:

// ❌ WRONG - comments not allowed
{
  "name": "Server", // server name
  "port": 25565 /* default port */
}

// ✅ CORRECT - remove all comments
{
  "name": "Server",
  "port": 25565
}

Games That Use JSON Config Files

GameConfig FilesCommon Issues
Minecraftwhitelist.json, ops.json, banned-players.jsonUUID formatting, player name case
Terrariaenabled.json (tModLoader)Mod name capitalization
EnshroudedServer configurationSilent reset on invalid JSON
Sons of the Forestdedicatedserver.cfg (actually JSON)Trailing commas
Hytaleconfig.json, world configsNested object structure

Terraria Users

Need to create an enabled.json for tModLoader? Try our Terraria enabled.json Generator — it handles the formatting automatically.

JSON Syntax Quick Reference

ElementSyntaxExample
StringsDouble quotes"Hello World"
NumbersNo quotes42, 3.14, -17
BooleansLowercase, no quotestrue, false
NullLowercase, no quotesnull
ArraysSquare brackets[1, 2, 3]
ObjectsCurly braces{"key": "value"}

Valid JSON Structure

{
  "stringValue": "text here",
  "numberValue": 42,
  "booleanValue": true,
  "nullValue": null,
  "arrayValue": [1, 2, 3],
  "nestedObject": {
    "inner": "value"
  }
}

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Frequently Asked Questions

Game servers often silently reset invalid JSON configs to defaults without warning. Even a single misplaced comma can cause this. Use this validator to check for syntax errors before uploading your config.

A Java error indicating invalid JSON syntax. Common causes include: trailing commas after the last item, single quotes instead of double quotes, missing commas between values, or unquoted property names.

Standard JSON does not support comments. Some applications use JSONC (JSON with Comments) or JSON5, but most game servers require strict JSON. Remove all // and /* */ comments before using.

Usually caused by: trailing commas after the last item in an array or object, single quotes instead of double quotes, unescaped special characters in strings, or missing commas between values.

Yes, JSON is case-sensitive. 'ServerName' and 'servername' are treated as different properties. Always match the exact capitalization your game server expects.

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