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Your adventure is about to begin
Generate perfect JSON from plain English and publish it as a live, publicly accessible mock API endpoint. Get instant, shareable URLs for frontend testing, prototypes, and demos—no backend setup required.
Generate JSON from plain English and instantly publish it as a live, shareable mock API endpoint. No servers, no setup—just instant APIs for prototyping, testing, and demos.
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Your adventure is about to begin
Get a permanent endpoint you can fetch from any app or tool
Share your API URL with teammates, clients, or in documentation
No backend setup, no servers, no deployment—just instant APIs
No coding required. No server setup. Just describe your data, edit it, and publish.
Write a simple prompt in natural language describing the JSON structure you need.
Our AI model generates the JSON code. You can then edit the data to fit your exact needs with live validation.
Your JSON is instantly validated. With one click, publish it as a live, publicly accessible mock API endpoint to power your apps and tests.
Turn any generated or edited JSON into a live, shareable mock API endpoint with a single click. Get a real URL you can use immediately in your apps, share with teammates, or use for frontend development and demos—no backend required.
Stop manually typing JSON and configuring mock servers. Generate complex JSON structures and get instant API endpoints in seconds—what used to take hours now takes moments.
The AI is trained to produce clean, valid JSON. Say goodbye to frustrating debugging sessions caused by a missing comma.
New to JSON or APIs? Describe what you want in plain English, see how it's structured correctly, and instantly understand how real APIs work by using your own live endpoint.
Try these prompts in the generator above. Edit the output as needed, then publish as a mock API.
Prompt: “An array of 3 users with id (number), name, email and createdAt ISO date.”
[
{ "id": 1, "name": "Alice Nguyen", "email": "alice@example.com", "createdAt": "2024-09-15T10:21:00Z" },
{ "id": 2, "name": "Ben Ortiz", "email": "ben@example.com", "createdAt": "2024-09-16T08:05:12Z" },
{ "id": 3, "name": "Chloe Park", "email": "chloe@example.com", "createdAt": "2024-09-17T14:39:50Z" }
]Prompt: “A product object with id, title, price, tags[], and a nested category object { id, name }.”
{
"id": "sku_1024",
"title": "Wireless Headphones",
"price": 79.99,
"tags": ["audio", "bluetooth", "wireless"],
"category": { "id": 7, "name": "Electronics" }
}Prompt: “A blog post with title, slug, author { name,email}, tags[], and published boolean.”
{
"title": "Demystifying JSON Schemas",
"slug": "demystifying-json-schemas",
"author": { "name": "Priya Shah", "email": "priya@example.com" },
"tags": ["json", "schemas", "best-practices"],
"published": true
}Prompt: “An order with id, userId, total, and items[] of { sku, name, qty, unitPrice }.”
{
"id": "ord_8451",
"userId": 2,
"total": 129.97,
"items": [
{ "sku": "sku_1024", "name": "Wireless Headphones", "qty": 1, "unitPrice": 79.99 },
{ "sku": "sku_2301", "name": "USB-C Cable", "qty": 2, "unitPrice": 24.99 }
]
}Build UI components instantly with mock API endpoints—no waiting for backend teams. Get real URLs to fetch from.
Share live API endpoints with stakeholders, create interactive demos, and showcase realistic API responses instantly.
Generate consistent mock data for automated tests, integration testing, and end-to-end test scenarios.
Teach JSON, APIs, and data structures with real examples. Students get hands-on experience with actual API endpoints.
Quickly mock up data structures for new features, validate ideas with stakeholders, and iterate on designs.
Create mock endpoints to test integrations with tools like Zapier, Airtable, or any service that consumes JSON APIs.
Once published, your API works exactly like any REST API. Here's how to fetch data from it:
fetch('https://formatjsononline.com/api/json/my-users')
.then(res => res.json())
.then(data => console.log(data))
.catch(err => console.error(err));import requests response = requests.get( 'https://formatjsononline.com/api/json/my-users' ) data = response.json() print(data)
curl https://formatjsononline.com/api/json/my-users
axios.get('https://formatjsononline.com/api/json/my-users')
.then(response => {
console.log(response.data);
});For an even faster experience, bring the power of our AI generator directly into your browser.
Get the Free Chrome ExtensionWhen you click 'Publish API', your JSON is saved and you get a permanent, public URL (like formatjsononline.com/api/json/your-endpoint). This URL works exactly like a real API—you can fetch data from it using JavaScript, Python, curl, or any HTTP client. It's perfect for testing, prototyping, and demos.
Yes! Once published, your API endpoint is immediately accessible from anywhere on the internet. You can use it in your web apps, mobile apps, share it with teammates, or use it in API testing tools like Postman. It returns your JSON data with proper CORS headers, so it works from browsers too.
Published endpoints remain active indefinitely. You can use them in long-term projects, demos, and educational materials. The endpoints are stable and won't change unless you create a new one with a different name.
Yes, absolutely. Both JSON generation and API publishing are completely free. We use leading AI models to offer powerful generation capabilities at no cost, with a fair daily rate limit to ensure availability for all users.
Yes. The AI excels at handling complex requests. You can ask for nested objects, arrays of objects, and mixed data types. The more specific your prompt, the better the result. For example, try asking for "An array of 2 blog posts, each with a title, author object (with name and email), and an array of tags".
While the AI has a very high accuracy rate, it can occasionally make a mistake. That's why we built this tool to seamlessly integrate with our core validator. After generation, the code is instantly checked for validity, and any errors are highlighted for you to fix immediately.
Yes—that's the key feature! After generating or pasting your JSON, enter an endpoint name and click 'Publish API'. You'll instantly get a live URL that returns your JSON. This is perfect for frontend development, testing, prototyping, and demos without setting up a backend.
Absolutely. You can paste any JSON data and publish it as an API endpoint. The tool works great for both AI-generated content and your own custom JSON. Just paste, validate, name your endpoint, and publish.
Yes. The JSON editor includes full editing capabilities, real-time validation, formatting tools, and error detection. You can customize any part of the generated JSON before publishing it as an API. Changes are validated instantly.
No signup required! Both JSON generation and API publishing are completely anonymous and free. Just visit the page, generate or paste your JSON, choose an endpoint name, and publish. That's it.
Choose from our suite of JSON tools to start processing your data right away.
Validate JSON syntax with AI-powered error detection and automatic fixing.
Beautify and format JSON with syntax highlighting and customizable indentation.
Generate JSON Schema validation rules from JSON objects.
Edit JSON with tree view, real-time validation, and statistics.
Generate TypeScript interfaces from JSON with type inference.
Compare two JSON files with visual diff highlighting and detailed analysis.
Transform your JSON into a real API endpoint you can access from anywhere. Perfect for prototyping, testing, and demos.
💡 Pro tip: You can generate JSON with AI or paste your own data, edit and validate it, then publish as a live mock API endpoint. Perfect for frontend testing, prototypes, and demos. For help, contact us.