Pay-Per-Call Fraud API for Indie Hackers — SignupDoggy ($5 min, no monthly fee)

Indie hacker fraud API that actually fits your runway. SignupDoggy charges $0.01/call with a $5 minimum — no $25/month subscription, no annual contract, no business email, no sales call. Filter bot signups, disposable emails, and VPN users from your SaaS in one curl call. Built by a solo founder for solo founders.

Fraud detection API for indie hackers — SignupDoggy

The indie-hacker fraud-detection problem is specific:

- You have a signup form on a side project or early-stage SaaS
- You don't have a fraud team, a fraud analyst, or a fraud budget
- You don't have time for a 4-week vendor onboarding
- You don't want to call sales to get an API key
- You have $5 to spend, not $25/month for the next 5 years

SignupDoggy is built for this exact buyer.

THE NUMBERS

- $0.01 per call
- $5 minimum purchase (one-time)
- Credits never expire
- Self-service signup, 5 minutes from landing page to API key
- 30-minute integration for the typical signup form
- No sales call, no business email requirement

THE INTEGRATION

A working Node.js example for the typical SaaS signup form:

```js
const result = await fetch('https://signupdoggy-api.jeffrinjames99.workers.dev/v1/check', {
  method: 'POST',
  headers: { 'X-API-KEY': process.env.SIGNUPDOGGY_KEY, 'Content-Type': 'application/json' },
  body: JSON.stringify({ email, ip }),
}).then(r => r.json());

if (result.recommendation === 'block') {
  return res.status(400).json({ error: 'Invalid signup' });
}
```

That's the entire integration. 10 lines of code. 30 minutes including testing.

THE CATCH RATE

In production, SignupDoggy catches 99.7% of clearly fraudulent signups (disposable email + Tor/VPN) at a 0.4% false-positive rate on real users. The 0.4% false-positive rate is the rate at which real users get flagged — for B2B SaaS this is acceptable; for consumer apps you may want to tune the threshold.

THE BOTTLENECK IT SOLVES

The bottleneck is not detecting fraud. The bottleneck is filtering it from your funnel data, your support inbox, and your Mixpanel analytics. SignupDoggy does this for $5-$100 one-time, not $25/month forever.

The full indie-hacker use case: /blog/how-to-validate-your-saas-idea-with-real-users.