Fraud Detection API for SaaS — $5 minimum, no monthly fee (SignupDoggy)

Fraud detection API for SaaS startups: SignupDoggy costs $0.01/call with a $5 minimum, no monthly subscription, no enterprise sales call. Built for 2-50 person teams. Disposable email + VPN + Tor + bot detection in one POST to /v1/check. The 2-stage funnel pattern + the SaaS startup playbook for keeping Mixpanel honest.

If you're building a SaaS — any SaaS, at any scale — you need fraud detection on your signup form. This page is the complete playbook: why you need it, what to look for, and how SignupDoggy compares to the alternatives.

## Why SaaS companies need a fraud-detection API

Every SaaS signup form is attacked:

- **5–15%** of all signups use disposable email addresses
- **2–5%** come from VPN, Tor, or residential-proxy IPs
- **0.5–2%** are pure bot signups from headless browsers
- **1–3%** are human abusers (free-trial abusers, promo-code hunters)

If you don't filter these, you get inflated Mixpanel numbers, support tickets from real users, Stripe Radar chargeback fees, and wasted Postgres rows.

## What to look for in a SaaS fraud-detection API

Seven criteria: disposable email detection, VPN/Tor detection, bot pattern recognition, sub-100ms latency, no sales call, no annual contract, webhook + dashboard.

## Compare fraud APIs for SaaS

SignupDoggy covers disposable email (200K domains), Tor exits (70K), VPN ASNs (24K), role-based patterns, and phone numbers. Sub-50ms p95. $0.01/call. $5 minimum. No monthly fee.

MaxMind lacks disposable email detection. Sift starts at $1,000/month. Cloudflare Turnstile is CAPTCHA-only, not a fraud API.

## How to integrate in 5 minutes

One POST to /v1/check with email + IP, get back a 0–1 risk score + allow/review/block recommendation. Sub-50ms p95. Inline-callable in your signup POST handler.

## The 2-stage funnel pattern

Pair SignupDoggy + Cloudflare Turnstile for maximum bot-block rate with zero user friction: Turnstile catches naive browser bots for free, SignupDoggy catches the headless scripts, residential proxies, and disposable emails that Turnstile can't see. Combined: 99%+ bot-block rate with 0% real-user friction.

## Real production numbers

In our own deployment: ~12% of all signups blocked at disposable-email check, ~3% at Tor/VPN, ~0.5% at bot pattern. 0.4% false-positive rate on real users.

## Get started

Buy credits at /pricing — $5 minimum, no monthly fee. Or try the playground for free — one free /v1/check call per day, no signup.