{ } JSON 验证器 — 在线检查 JSON 语法

Validate any JSON string instantly. Get a clear error message with line number when syntax is wrong. Free online JSON syntax checker.

Not sure if your JSON is valid? Paste it here and click Validate. The tool checks every bracket, quote, and comma and shows you a green checkmark for valid JSON or a red error with the exact line number for invalid JSON.

Input JSON

0 chars

Output

0 chars

How to Use

Paste your JSON

Copy or type your JSON data into the left input area. Minified or messy JSON is fine.

Click Format

Press the Format button (or Ctrl+Enter) to instantly beautify and validate your JSON with proper indentation.

Copy the result

Use the Copy button to copy the formatted output. Fix any errors shown in the status bar.

Frequently Asked Questions

What is a JSON formatter? +

A JSON formatter (also called JSON beautifier or JSON pretty printer) takes minified or poorly indented JSON data and reformats it with proper indentation and line breaks, making it human-readable. It also validates that the JSON syntax is correct.

How do I format JSON online? +

Paste your JSON into the input area, then click Format. The tool automatically detects syntax errors and shows them with the line number. Your formatted JSON appears in the output area ready to copy.

What is the difference between format and minify? +

Formatting adds spaces and line breaks for readability. Minifying removes all unnecessary whitespace to reduce file size — useful for production APIs and config files.

Does this JSON formatter store my data? +

No. Everything runs 100% in your browser using JavaScript. Your JSON data never leaves your computer and is never sent to any server.

Can I validate JSON without formatting it? +

Yes — click the Validate button to check if your JSON is valid without changing its structure. The tool shows a green checkmark for valid JSON or a red error message with the exact problem location.

完整指南：JSON格式化与验证工具

什么是JSON格式化工具？

JSON格式化工具应用RFC 8259规范：正确的缩进、换行符，并在格式化的同时进行验证。生产环境中的API响应通常是压缩在单行的数千字符，该工具让其变得可读并识别语法错误。

适用人群：调试fetch()响应的前端工程师、编写测试数据的后端工程师，以及审查部署配置的DevOps团队。

如何使用

粘贴JSON到输入区域——压缩、部分格式化或有错误的JSON均可接受。
点击格式化（或按Ctrl+Enter）——一次性完成验证和美化。
查看状态栏：绿色✓表示有效，红色✕显示精确错误位置。
使用压缩获得生产环境所需的紧凑输出。

专业技巧

尾随逗号（{"a":1,}）在JSON中无效，但在JavaScript中有效——验证器会检测到。
未加引号的键和单引号字符串在JSON中同样无效。
gzip压缩可将JSON减小约70%，格式化JSON在生产环境几乎没有额外成本。