Getting Started

This guide walks through the whole first-use flow: signing up, getting an API key, creating a template, and generating your first piece of synthetic JSON data.

1. Sign up and get your API key

Signing up starts with a single API call, then finishes on Stripe's hosted checkout page. Your API key is issued after payment is confirmed — you'll get it by email and on the confirmation page, not in the signup response itself. You'll need:

• An email address.
• A plan tier: starter, growth, or business (larger enterprise plans are arranged directly with sales, not via self-serve signup). There is no free tier. Only starter starts with a 30-day free trial, then converts to the plan's monthly rate; growth and business are billed immediately at signup, with no trial.

After this call succeeds, you'll be redirected (via the returned checkoutUrl) to Stripe's hosted checkout page to enter payment details.

curl -s -X POST https://api.jsonfabrica.com/v1/signup \
  -H 'content-type: application/json' \
  -d '{"email":"[email protected]","tier":"starter"}'

A successful response looks like this:

{
  "tenantId": "tenant_...",
  "tier": "starter",
  "status": "pending_payment",
  "checkoutUrl": "https://checkout.stripe.com/..."
}

Redirect the user's browser to checkoutUrl to complete payment on Stripe's hosted page.

Once payment completes, your API key is emailed to you and available once via GET /v1/signup/session/:sessionId (pass the session_id Stripe appends to your checkout return URL). Save it immediately — it's only ever shown once and there is no way to retrieve it again later if you lose both the email and that one-time view.

curl -s https://api.jsonfabrica.com/v1/signup/session/<sessionId>

While payment is still processing:

{ "status": "pending" }

Once fulfilled:

{
  "status": "fulfilled",
  "tenantId": "tenant_...",
  "tier": "starter",
  "apiKey": "sk_..."
}

If your email is rejected before you ever reach Checkout (e.g. disposable email domains), you'll get a response like {"tenantId":"tenant_...","tier":"starter","status":"blocked","blockReason":"..."} with no checkoutUrl.

2. Authenticate your requests

Every API call after signup must include your API key in the Authorization header:

Authorization: Bearer sk_...

You can sanity-check that your key works with:

curl -s https://api.jsonfabrica.com/v1/whoami \
  -H 'Authorization: Bearer sk_...'

which returns:

{ "tenantId": "tenant_...", "role": "user" }

3. Understand template syntax

Templates are plain JSON documents with placeholders inside them. Placeholders call a data-generation function using angle brackets:

<functionName(arg1, arg2, ...)>

For example, a minimal template that generates a random full name and an auto-incrementing user id looks like this:

{ "name": "<getRandomFullName()>", "id": "<createSeq('userId')>" }

Templates also support loops and conditionals, for example:

<for(i, 1, 3)><if(getVar(i) == 1)>first<else>rest<endIf><end_for>

See the Function Reference for the full list of available functions.

4. Create your first template

Create a template by sending its name and body to the API:

curl -s -X POST https://api.jsonfabrica.com/v1/templates \
  -H 'Authorization: Bearer sk_...' \
  -H 'content-type: application/json' \
  -d '{
        "name": "user-profile",
        "body": "{ \"id\": \"<createSeq(\"users\")>\" }"
      }'

A template must contain at least one placeholder — a template made up of plain literal text only will be rejected. Every function you reference in a template must be one of the built-in supported functions.

5. Generate data

Once your template is saved, generate data from it at any time:

curl -s -X POST https://api.jsonfabrica.com/v1/templates/<templateId>/generate \
  -H 'Authorization: Bearer sk_...' \
  -H 'content-type: application/json' \
  -d '{}'

A successful response looks like this:

{
  "data": { "id": 1 },
  "meta": {
    "seed": 12345,
    "templateId": "tpl_...",
    "generatedAt": "2026-08-08T00:00:00.000Z"
  }
}

• data is your generated JSON document.
• meta.seed is the random seed used for this generation run — pass the same seed back in on your next call to reproduce identical output.
• meta.generatedAt is the timestamp of generation.

If you'd rather generate data without saving a template first, you can send the template body directly to a one-off endpoint:

curl -s -X POST https://api.jsonfabrica.com/v1/templates/generate \
  -H 'Authorization: Bearer sk_...' \
  -H 'content-type: application/json' \
  -d '{"body":"{ \"n\": \"<getRandomNumber(1,10)>\" }"}'

This still counts toward your usage, but nothing is saved to your account.

What's next

• Browse the full Function Reference to see every available function, its parameters, and example usage.
• Read about billing and plan tiers to understand how usage is measured and billed.