JSON Formatter & Validator
Parse / Pretty Print / Minify / Validate / Escape / Unescape
What Is a JSON Formatter?
A JSON formatter adds indentation and line breaks to compressed JSON so it becomes readable and editable. Whether you are dealing with a dense API response, a compact config file, or a JSON fragment buried in logs, formatting makes the structure and every field instantly clear. After formatting, use our JSON Compressor to remove whitespace; pair it with the HTTP Test Tool to send requests, and the Timestamp Converter to read Unix timestamps inside fields. You can also pretty-print locally with Python's json.dumps(indent=2) or JavaScript's JSON.stringify(obj, null, 2), but this tool works right in your browser with no setup.
Common Use Cases
API debugging: backend JSON responses are often minified to one line. Paste them here to reveal structure and values, then use the HTTP Test Tool to trace issues faster. Config editing: format package.json, tsconfig.json, and similar files before editing to catch missing commas or mismatched brackets. Log analysis: format JSON fragments from logs to quickly locate abnormal fields and error messages. Data migration: export JSON from a NoSQL database, validate field completeness here, then compress it with the JSON Compressor before importing into the target system.
How to Use This Tool
Paste your JSON into the left input box, choose 2-space or 4-space indentation, and click Format to pretty-print. Click Minify to remove all whitespace and produce a single-line JSON. Switch to the tree view to explore nested structures with expand/collapse controls. You can copy the result to the clipboard or download it as a .json file. If the input is not valid JSON, the tool highlights the exact line and column so you can fix it quickly.
Conversion Tips & Techniques
How do I convert JSON to TypeScript / Java / Go?
When integrating APIs, mapping a JSON response to type definitions saves time. First format and validate the JSON here so you do not carry invalid structure into your types. Then map fields: TypeScript uses string, number, boolean, nested objects become interfaces, and arrays use the element type; Java maps to POJO fields; Go maps to struct fields, remembering to export fields with an uppercase first letter. Two common pitfalls: integers longer than 16 digits exceed JavaScript's safe integer range, so type them as string or bigint; and optional API fields should be marked optional (?).
How do I convert JSON to XML / YAML / CSV?
These formats have different expressiveness, so check structural compatibility before converting:
- JSON → XML: map key-value pairs to tags and arrays to repeated tags; escape
<,&, and>as XML entities. - JSON → YAML: YAML 1.2 is a superset of JSON, so most parsers can read JSON directly; when converting back, remember YAML is indentation-sensitive.
- JSON → CSV: this only works for a flat array of objects, where keys become headers; nested objects must be flattened first (for example,
{"a":{"b":1}}becomes columna.b). - Validate before and after: confirm the JSON is valid here, then validate the target format after conversion to avoid losing escapes or numeric precision.
How do I sort JSON keys?
Sorted keys make API documentation examples tidy and diffs between responses clearer. In JavaScript, a one-line recursive sort is: const sortKeys = o => Array.isArray(o) ? o.map(sortKeys) : Object.fromEntries(Object.keys(o).sort().map(k => [k, sortKeys(o[k])])). Note that the JSON standard (RFC 8259) does not guarantee key order; modern JS and Python 3.7+ preserve insertion order as an implementation detail. Sorting is for readability and diffing only—do not rely on it in business logic.
Why do long numbers end in 0 after formatting?
Most online JSON formatters, including this one, rely on JSON.parse, which parses numbers as IEEE 754 double-precision floats. The safe integer limit is 253-1 (16 digits, 9007199254740991). Numbers with 17 or more digits—order IDs, Snowflake IDs, social platform user IDs—may silently lose precision and end in 0. Test it: paste {"id":12345678901234567890} and format. The recommended fix is to serialize long IDs as strings at the transport layer (for example, string serialization annotations in Java or the json-bigint library in JS), or use a lossless parser that preserves the original text. Passing long IDs as strings is the industry standard.
Common JSON Syntax Errors
If formatting fails, you are probably hitting one of these common issues. This tool reports the exact line and column so you can fix it quickly:
- Unquoted keys:
{name: "x"}should be{"name": "x"}—JSON keys must be double-quoted strings. - Single quotes: JSON strings use double quotes only; change
'hello'to"hello". - Trailing commas: the last item must not be followed by a comma, so
[1, 2,]is invalid. - Comments: standard JSON does not support
//or/* */; this tool can strip comments before formatting. - Boolean/null case: use lowercase
true,false, andnull.
What If Chinese Characters Show as \uXXXX?
When you paste JSON, Chinese characters may appear as \uXXXX sequences (for example, \u7b80\u7f8e for 简美). This is not corruption—it is a Unicode escape, using \u followed by four hexadecimal digits. It usually happens because the API enforced ASCII-safe output or because the string was serialized that way.
To restore readable text, paste the text into this tool and click Format. The standard JSON.parse implementation automatically converts \uXXXX back to the original characters. If you need the reverse—converting readable text to \u escapes for legacy systems—this tool supports escaping as well. Examples:
{"name":"\u7b80\u7f8e\u5de5\u5177"}formats to{"name":"简美工具"}.- If you see a long string of
\ucharacters, it is likely double-escaped; format it layer by layer. - When debugging "garbled" Chinese, first confirm whether it is Unicode escaping (
\uXXXX) or a real encoding issue such as UTF-8 interpreted as GBK.
Modern browsers and most languages (including JavaScript's JSON.stringify) keep Chinese characters as-is by default and only escape to \u when ASCII safety is required. This tool displays both forms so you can match whichever interface specification you need.
Frequently Asked Questions
Does formatting change my data?
No. JSON formatting only adjusts indentation, line breaks, and whitespace. It does not change any keys, values, or data structure, so the semantic meaning remains identical before and after formatting.
Is this JSON formatter safe? Will my data leak?
Yes, it is safe. All formatting, minifying, and validation runs entirely in your browser. Your data is never uploaded to any server.
What is the difference between formatting and minifying?
Formatting adds indentation and line breaks to make JSON readable. Minifying removes all whitespace and line breaks to produce a single compact line, reducing file size for transmission. This tool supports both—just switch indentation or click the Minify button.
What errors does the validator catch?
Common errors include mismatched brackets or quotes, missing or extra commas, unquoted keys, comments (not allowed in standard JSON), and trailing commas. The tool pinpoints the exact line and column to help you fix the issue quickly.
What is the difference between tree view and text view?
Tree view displays JSON as collapsible nodes, which is ideal for browsing complex nested data quickly. Text view shows the formatted raw text, which is better for copying or line-by-line comparison. You can switch between them at any time, and tree view supports one-click fold/unfold.
How is JSON formatting different from XML formatting?
JSON uses braces and brackets to express hierarchy, while XML uses nested tags. JSON is more compact and efficient to transmit, making it the standard format for modern web APIs. This tool focuses on JSON formatting and validation, including comment stripping and escape handling, and can also minify JSON into a compact single-line format.
What if a large JSON file lags?
If the JSON file is larger than 1 MB, check whether it contains unnecessary whitespace or comments. JSON under 500 KB usually formats instantly in the browser. You can improve speed by minifying first and then formatting. For very large exports, such as database dumps, split the input or preprocess with the command-line tool jq.
What is the difference between JSON arrays and objects, and how do I format them?
JSON objects use curly braces {} to hold key-value pairs where every key must be a double-quoted string. JSON arrays use square brackets [] to hold an ordered list of values, which can be strings, numbers, booleans, objects, or arrays. This tool formats both objects and arrays, supports tree-view expansion, and displays each array element on its own line for easy verification.
How do I restore Chinese characters from \uXXXX escapes?
That is a Unicode escape sequence. For example, "\u7b80\u7f8e" is 简美. It is not corrupted text—it is the Chinese character encoded as \u plus four hex digits. This tool parses it with standard JSON.parse and restores the original Chinese automatically. If you only see a long string of \u characters, it may be double-escaped; paste it here and format layer by layer.
Will Chinese characters become garbled after formatting? Do I need to escape them?
No, they will not become garbled, and you do not need to escape them manually. Modern browsers and most languages, including JavaScript's JSON.stringify, keep Chinese characters as-is by default and do not force them into \uXXXX escapes. Only escape them when the receiving system explicitly requires ASCII-safe output. This tool lets you view both forms so you can match the required interface specification.
How do I find a field inside a JSON file with tens of thousands of lines?
Use two approaches together: first fold layers in tree view to narrow down the scope, or use Ctrl+F in text view to find the field name. Once you know the path, build a JSONPath expression such as $.store.book[0].title and use a JSONPath library in your code or browser console to extract the value. Formatting first is strongly recommended because finding fields in a minified single-line JSON is nearly impossible.
Can JSON be converted to Excel or SQL?
An array of objects is a good fit for CSV or Excel, where keys become column headers and each object becomes a row. Converting to SQL usually means generating CREATE TABLE or INSERT statements from the JSON, which requires flattening nested structures first. Whatever conversion you perform, format and validate the JSON here first and confirm field types to avoid importing dirty data.