JSON Standards & Data Guide
JSON (JavaScript Object Notation) is the most popular format for sharing data on the web. It is lightweight, plain text, and supported by all programming languages. Web APIs, mobile apps, and config files use JSON every day.
1. Basic JSON Rules
JSON has strict syntax rules: - **Keys:** Must always be wrapped in double quotes (`"name"`). Single quotes are not allowed. - **Strings:** Must use double quotes (`"hello"`). - **Numbers:** Can be integers or decimals (`42`, `3.14`). - **Booleans:** Must be lowercase `true` or `false`. - **Null:** Must be lowercase `null`. - **Arrays:** Lists wrapped in square brackets `[1, 2, 3]`. - **Objects:** Key-value maps wrapped in curly braces `{"key": "value"}`.
2. Common JSON Mistakes
Watch out for these common errors: - **Trailing Commas:** Do not put a comma after the last item in a list or object. - **Single Quotes:** Replacing `"key"` with `'key'` will cause a syntax error. - **Unescaped Quotes:** Use `\"` inside strings if you need literal quotation marks.
3. JSON Schema & Validation
JSON Schema lets you define rules for your data. You can specify: - Required fields (e.g. `id` and `email`). - Data types for each field (string, number, boolean). - Minimum or maximum values and string length limits.
Engineering Best Practices & Guidelines
Always validate untrusted JSON before parsing it in backend code.
Format JSON with 2 spaces when reading or debugging.
Minify JSON when sending it over the network to save bandwidth.
Use our free online JSON Formatter and Validator to fix errors quickly.
Frequently Asked Questions
Q1. Why does JSON reject trailing commas?
The official JSON standard forbids trailing commas to ensure every parser reads the data the same way without bugs.
Q2. How do I format JSON in my browser?
Paste your raw JSON into our JSON Formatter tool. It will check syntax and format it with 2-space indentation instantly.