JSON Decoder Online
Paste any JSON string to decode, parse, and format it instantly. Validates syntax and highlights the exact error line. Free, no sign-up, runs entirely in your browser.
What is JSON Decoding?
JSON decoding (also called JSON parsing or deserialization) is the process of taking a raw JSON string and converting it into a structured data object your code can work with. When an API returns a response body like {"name":"Alice","age":30}, decoding that string gives you an object with actual properties you can access.
This tool decodes JSON entirely in your browser. Paste the raw or escaped JSON string into the input box and click Beautify — the decoder validates the syntax, reports any errors with the exact line number, and formats the output with consistent indentation so the structure is easy to read.
How to Decode JSON Online
- Paste your JSON string into the input box on the left.
- Click Beautify to decode and format the JSON with indentation.
- If the JSON is invalid, the decoder highlights the error line and shows the exact syntax problem.
- Click Copy to copy the decoded, formatted output.
JSON Decode vs Parse vs Deserialize
| Term | Meaning | Example |
|---|---|---|
| JSON decode | Convert JSON string → data object | json_decode() in PHP |
| JSON parse | Same as decode — common in JS/Python | JSON.parse() in JavaScript |
| JSON deserialize | Same concept, common in Java/C#/Go | ObjectMapper.readValue() in Java |
| JSON unmarshal | Same concept, Go terminology | json.Unmarshal() in Go |
JSON Decode by Language
| Language | Function / Method | Returns |
|---|---|---|
| JavaScript | JSON.parse(str) | Object / Array |
| PHP | json_decode($str, true) | array (assoc) |
| Python | json.loads(str) | dict / list |
| Go | json.Unmarshal([]byte, &v) | struct or map |
| Java | objectMapper.readValue(str, T.class) | typed object |
| C# | JsonSerializer.Deserialize<T>(str) | typed object |
| Ruby | JSON.parse(str) | Hash / Array |
| Rust | serde_json::from_str(&str) | typed struct |
| Kotlin | Json.decodeFromString<T>(str) | typed object |
| Dart | jsonDecode(str) | dynamic Map |
Frequently Asked Questions
What is the difference between JSON decode and JSON parse?
They are the same operation. 'JSON decode' is the term used in PHP and some other languages. 'JSON parse' is the JavaScript/Python convention. Both convert a raw JSON string into a native data structure you can work with in code.
Is my JSON data safe when I use this decoder?
Yes. The decoder runs entirely in your browser using JavaScript. Your JSON string is never sent to any server. This makes it safe to decode sensitive or proprietary JSON data.
What does it mean when JSON decode returns null?
In PHP, json_decode() returns null on failure (invalid JSON or depth exceeded). Always check json_last_error() !== JSON_ERROR_NONE after decoding to detect failures. In JavaScript, JSON.parse() throws a SyntaxError instead of returning null.
Can I decode a JSON string that contains escaped characters?
Yes. Standard JSON escape sequences like \n, \t, \u0041, and \\ are decoded automatically. Paste the raw JSON string (including surrounding quotes if it is a JSON string value) and the decoder will handle the escapes.
How do I decode a JSON array vs a JSON object?
Both are valid JSON root values. An array starts with [ and an object with {. This decoder handles both — paste either and it will format the output correctly.
What error does invalid JSON produce?
This decoder highlights the exact error line and shows the parse error message. Common errors: unexpected token (typo or missing comma), trailing comma (not allowed in standard JSON), unquoted keys, single-quoted strings.
Frequently Asked Questions
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