What is JSON?
A plain-English definition, and the tools that work with it.
JSON (JavaScript Object Notation) is a lightweight, text-based format for structured data, built from key–value pairs and lists. It's the standard way apps and APIs exchange data because it's easy for both humans and machines to read.
- JSON uses double quotes around keys and string values, and allows no trailing commas or comments, the top causes of 'invalid JSON'.
- It maps naturally to objects and arrays in almost every programming language, which is why APIs return JSON.
- Minified JSON is one long line. A formatter re-indents it so you can read and debug the structure.
Tools for JSON
Free, private and in your browser. No sign-up.
JSON Formatter
Format, validate and minify JSON in your browser with pinpoint error line + column, jump-to-error, key sorting and live editing: nothing is uploaded.
JSON Validator
Validate JSON against RFC 8259 with the exact error line, column and a caret under the bad character. Get plain-English explanations, one-click auto-fix for trailing commas and single quotes, plus depth, key-count and type stats, nothing uploaded.
CSV to JSON
Convert CSV to JSON in your browser. Paste or drop a.csv and get a clean array of objects or arrays with a header toggle, optional number/boolean type inference and pretty or minified output. Nothing is uploaded.
JSON Tree Viewer
Explore JSON as an interactive, collapsible tree. Expand or collapse any branch, see type and array-length badges, search keys and values with live highlighting, and copy any node's value or its JSONPath in one click, all 100% in your browser.
JSON problems we solve
Hit one of these? Here's the fix.
- My JSON is invalid and I can't find the error'Unexpected token' almost always means one stray character. A validator points straight at it so you're not hunting by eye.
- I need to convert a CSV file to JSONMove data between a spreadsheet and code without a script. Header row becomes keys, each row becomes an object.
- My code or data is minified and unreadableOne long line of minified everything? Pick the matching formatter and get properly indented, readable code back.
Frequently asked questions
Related terms
- CSVCSV (Comma-Separated Values) is a plain-text format for tabular data: each line is a row and commas separate the columns. It's the simplest, most universal way to move spreadsheet data between programs, databases and code.
- Base64Base64 is a way of encoding binary data (like an image or file) into plain ASCII text using 64 safe characters. It lets you embed or transmit binary content through systems that only handle text, such as email, JSON or data URIs.
Keep exploring
Problems we solve
Definitions
From the blog
- Why AI Crawlers Don't Run JavaScript, and What That Costs You
- How to Generate TypeScript Types from JSON (API Responses Made Type-Safe)
- JSON-LD vs. Microdata vs. RDFa: Which Structured Data Format Should You Use?
- Why and How to Minify JavaScript (and CSS) for a Faster Site
- FAQ Schema: A Practical Guide to Winning Rich Results
Common tasks
Try JSON Formatter
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