Pay-Per-Call API — fraud detection for $0.01/call, no monthly fee (SignupDoggy)

Pay-per-call fraud-detection API for indie hackers and SaaS startups. $0.01 per call, $5 minimum, credits never expire. The cheapest fraud API that ships to production: 12x-480x cheaper than IPQS, MaxMind, or Sift at the same volume.

If you've been shopping for a fraud-detection API, email validation API, or any other developer tool, you've hit the same wall: every "enterprise" vendor wants a $25/month minimum, an annual contract, or a sales call. **Pay-per-call** pricing flips that — you pay only for what you use, no minimum, no subscription.

This page is the indie-hacker / SaaS-startup playbook for evaluating pay-per-call APIs (and a deep dive on why SignupDoggy is the cheapest one that still ships to production).

## What "pay-per-call" actually means

A pay-per-call API charges you only for the requests you make. The math is straightforward:

- **Per-call cost** — the price of one request (SignupDoggy: $0.01)
- **No minimum spend** — you can buy 100 calls or 100,000 calls
- **No monthly subscription** — there's no recurring charge for "access to the API"
- **No annual contract** — you can stop using the API at any time

## Why pay-per-call wins for indie SaaS

Three concrete reasons:

**1. Cash flow matches revenue.** When your SaaS hits $20 MRR, you don't want to be locked into a $25/month IPQS contract. Pay-per-call aligns your fraud-detection spend with your revenue.

**2. No vendor lock-in.** The moment you're not locked into a 12-month contract, you can switch APIs in an afternoon. This pushes vendors to compete on quality.

**3. You only pay for real value.** If your signup form gets 10 fake signups today and 0 tomorrow, your bill reflects that. With a subscription, you pay the same regardless.

## The SignupDoggy pay-per-call model

| Tier | Price | Calls | Per-call cost |
|---|---|---|---|
| Solo | $5 one-time | 1,000 | $0.005 |
| Pro | $25 one-time | 5,000 | $0.005 |
| Scale | $100 one-time | 25,000 | $0.004 |

Credits **never expire**. No monthly fee on the one-time packs. You can mix and match.

## Compare to subscription alternatives

At 5,000 signups/month sustained for 12 months:

- IPQS: $300–$960/year
- MaxMind: $300–$900/year
- Sift: $12,000+/year
- SignupDoggy: $25/year (Pro pack, refilled annually)

That's a **12x–480x cost difference** at the same volume.

## What to look for in a pay-per-call fraud API

Five criteria: real coverage, sub-100ms latency, no minimums, credits that don't expire, no sales call. SignupDoggy hits all five. See /pricing for the full breakdown.