> ## Documentation Index
> Fetch the complete documentation index at: https://docs.signuprisk.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Signup Risk API

> Analyze registrations with an explainable 0–100 signup-risk score and allow, review, or block recommendation.

Signup Risk API evaluates an email address — with optional signup context such as a submitted name, client IP, or industry — and returns a deterministic, explainable decision you can act on at registration time.

## What Signup Risk API does

Send an email address to the analysis endpoint and receive:

* a **0–100 risk score**
* a **risk band**: `low`, `moderate`, `high`, or `very_high`
* a recommended action: **`allow`**, **`review`**, or **`block`**
* individual **risk checks** with evidence and per-check contributions, when requested
* a plain-language **explanation** of the decision, when requested
* **decision context**: warnings, usage and quota snapshot, and plan information

Every response answers one question with evidence you can inspect, log, and audit.

## The core product question

> **Should this registration receive access?**

Signup Risk API turns that question into a concrete recommendation — `allow` it, send it to `review`, or `block` it — backed by a deterministic score and check-level evidence rather than an opaque verdict.

## Common use cases

* **SaaS and free-trial protection** — decide which signups get access before they consume resources
* **Seller onboarding** — route new sellers into review queues based on risk
* **Community registration** — slow down or stop bulk and throwaway account creation
* **Account-linked promotion protection** — filter signups created to claim bonuses
* **Inbound form routing** — sort leads by risk before they reach your CRM
* **Bulk operational reviews** — score existing lists asynchronously with bulk jobs

## What it is not

Signup Risk API is a signup-decision API, not a general identity or messaging tool. It is **not**:

* SMTP mailbox verification — it does not send mail or confirm an inbox exists
* KYC or identity verification — it does not verify government identities or documents
* device fingerprinting — it scores the email and submitted context, not the device
* payment transaction scoring — it does not evaluate transactions or chargebacks
* content moderation — it does not analyze message or post content

## Next steps

<Card title="Make your first request" icon="rocket" href="/quickstart">
  Get an API key and send your first analysis request in a few minutes.
</Card>

<Card title="Get an API key" icon="key" href="https://app.signuprisk.com/sign-up">
  Create an account at app.signuprisk.com and issue a first-party API key.
</Card>