I Built a Free Synthetic Data Generator — Here's How (React + Tailwind)

We've all been there — you need 10,000 realistic user records to test your app, or a batch of fake healthcare data for a demo, or transaction logs to stress-test a dashboard. So you either:

1. Write a janky script that generates "User_1, User_2, User_3..."


2. Spend 30 minutes configuring a CLI tool


3. Use a SaaS tool that limits you to 100 rows on the free tier

I got tired of this, so I built DataForge — a free, browser-based synthetic data generator that creates realistic fake data instantly. No signup, no server, no limits.

🔗 Try it live

What It Does

DataForge generates realistic fake data across 9 data types in two categories:

📊 General Data

• 
  Users — Names, emails, phones, DOB, company, job title


• 
  Addresses — Street, city, state, ZIP, coordinates


• 
  Transactions — Amounts, merchants, categories, status

🏥 Healthcare / HIPAA-Safe

• 
  Patients — MRN, blood type, allergies, conditions, insurance


• 
  Medical Records — ICD-10 codes, vitals, visit types, clinical notes


• 
  Prescriptions — Real medications, dosages, DEA numbers, NDC codes


• 
  Lab Results — 26 real lab tests with reference ranges and flags


• 
  Insurance Claims — Charged/allowed/paid amounts, claim status


• 
  Healthcare Providers — NPI numbers, specialties, credentials

All data is 100% synthetic — no real patient data, no HIPAA risk.

Key Features

⚡ Generate Up to 50,000 Records Instantly

Everything runs client-side. No API calls, no server. Your data never leaves your browser.

🎬 Custom Scenarios

This is where it gets powerful. Instead of random data, you can define rules:

Preset Scenarios:

• 🧓 Elderly Patient Cohort (ages 65+)


• 👶 Pediatric Cohort (ages 0-17)


• 🚨 Critical Lab Values


• 💰 High-Value Transactions ($5K+)


• 🕵️ Fraud Patterns


• ❌ Denied Claims Batch


• 🗑️ Dirty/Messy Data (with nulls and errors)

Custom Builder:

• Set null rates per field (0-80%)


• Define value ranges (age 65-95, amount $10K+)


• Force specific values (status = "Denied")


• Add custom value pools


• Control duplicate rates and error injection

📤 Export Formats

• 
  JSON — Standard structured data


• 
  CSV — For spreadsheets and databases


• 
  SQL — Ready-to-run INSERT statements


• 
  HL7 FHIR — Healthcare interoperability standard

🌱 Reproducible with Seeds

Set a seed value and get the exact same data every time. Perfect for consistent test suites.

How I Built It

Tech Stack

• 
  React 18 + TypeScript


• 
  Tailwind CSS — Dark HD interface


• 
  Vite — Fast builds


• 
  Custom seeded PRNG — No external faker library needed

The Seeded Random Number Generator

Instead of using Math.random() (which isn't seedable), I built a custom PRNG based on a simple hash function:

typescript

class SeededRandom {

  private seed: number;



  constructor(seed: number) {

    this.seed = seed;

  }



  next(): number {

    this.seed = (this.seed * 16807 + 0) % 2147483647;

    return this.seed / 2147483647;

  }



  nextInt(min: number, max: number): number {

    return Math.floor(this.next() * (max - min + 1)) + min;

  }



  pick<T>(array: T[]): T {

    return array[this.nextInt(0, array.length - 1)];

  }

}





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If you work in Health IT, you know the pain:



❌ You can't use real patient data for testing (HIPAA)

❌ Epic/Cerner sandboxes have limited test patients

❌ Synthea is powerful but requires Java + CLI setup

❌ Most online generators don't understand healthcare data



DataForge fills this gap:



✅ FHIR-native export — Generate valid FHIR Bundles

✅ Real ICD-10 & CPT codes — Not random strings

✅ Clinical scenarios — Elderly cohorts, critical labs, denied claims

✅ Runs in the browser — Share the URL with your QA team

✅ 50K records — Enough for load testing



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What's Next

  I'm planning to add:



 Custom schema builder (define your own data types)

 API endpoint mode (use as a mock API)

 Relationships between tables (foreign keys)

 More healthcare standards (HL7v2 messages, C-CDA)

 Localization (non-US names, addresses, phone formats)





If this tool saves you time, drop a ⭐ on the repo or leave a comment. I'd love to hear how you're using it!