TOOLGENIECreate, Edit, Format and Validate JSON Online
Create JSON online with this free JSON editor. Paste or write JSON, format it, validate errors, minify it, and copy or download the result.
Everything runs in your browser. Press Ctrl/Cmd+Enter to format. Your last JSON is saved locally on this device.
0 characters · 0 lines · 0 bytes
How to Create JSON Online
- Paste JSON, write it from scratch, upload a .json file, or click Sample JSON.
- Click Format JSON to beautify it, or Validate JSON to check syntax only.
- If there is an error, use Jump to line, fix the token, and run the check again.
- Minify the payload when you need a compact API body.
- Copy the result, download a .json file, or convert it to CSV or TypeScript.
About This Free JSON Editor
This page is a free browser JSON editor for creating, editing, formatting, and validating JSON. It is built for the search “create json”: write a file, check it, and leave with a clean download. Need a dedicated checker first? Use the JSON validator. Want only pretty-print? Open the JSON formatter.
All processing stays on your device. The last draft can be restored from localStorage so a refresh does not wipe unfinished work.
A Short Guide to Creating JSON
What is JSON?
JSON (JavaScript Object Notation) is a text format for structured data. It uses objects, arrays, strings, numbers, booleans, and null. APIs, config files, and many databases speak JSON because it is easy for both people and programs to read.
How do I create a JSON file?
Start with an object or an array. Use double quotes around every key and every string. Separate fields with commas, but do not leave a comma after the last field. When the editor says the JSON is valid, click Download .json. That file can be opened in any text editor, sent to an API, or imported into another tool.
Valid JSON example
{
"name": "Ada",
"active": true,
"tags": ["math", "computing"]
}More copy-ready samples live on the JSON examples page.
Common JSON mistakes
- Single quotes:
{'name': 'Ada'}is invalid. Use double quotes. - Trailing commas:
{"name": "Ada",}fails in strict JSON. - Unquoted keys:
{name: "Ada"}is JavaScript, not JSON. - Comments:
// noteis not allowed in standard JSON. - Mismatched brackets: every
{needs a}.
How to fix “unexpected token” errors
An unexpected token means the parser hit a character it did not expect — often a comma, quote, or bracket. This editor reports the line and column. Click Jump to line, look at the highlighted text, and check the character just before the error. After you fix it, validate again. If you only need a syntax report, the JSON validator is the focused page for that job.
JSON object vs JSON array
Use an object when one record has named fields: {"id": 1, "name": "Ada"}. Use an array when you have a list: [{"id": 1}, {"id": 2}]. CSV conversion works best on an array of objects. Convert that list with JSON to CSV, or generate types with JSON to TypeScript.
Frequently Asked Questions (FAQ)
Can I create JSON for free?
Yes. This JSON editor is free. Write JSON, format it, validate errors, minify it, and download a .json file with no account.
How do I create a JSON file online?
Type or paste JSON, click Format JSON, then Download .json. The Sample JSON button is a safe starting point if you are new to the format.
How do I fix an unexpected token JSON error?
Open the error, jump to the reported line, and fix the comma, quote, or bracket. Validate again until the green success message appears.
Is my JSON uploaded to ToolGenie?
No. The editor, validator, minifier, and converters run in your browser. A local draft stays on this device only.
What is the difference between a JSON object and a JSON array?
An object is named keys in curly braces. An array is an ordered list in square brackets. Many API responses wrap an array of objects inside one object.
Can this JSON editor convert JSON to CSV or TypeScript?
Yes. Use Convert to CSV or Convert to TypeScript on this page, or open the dedicated JSON to CSV and JSON to TypeScript tools.
Tips for Creating Clean JSON
- Format first, then minify. Pretty JSON is easier to debug.
- Use the JSON minifier when you only need a compact payload.
- Keep secrets out of any online tool unless you must paste them.
- Sort keys when you want two configs to compare more easily.