SignupBouncer: block disposable emails and fake signups

# SignupBouncer > SignupBouncer is an API that checks new signups for disposable emails, Gmail aliases and repeat accounts. Each check answers allow, challenge or block, with a score and the reasons. It looks at the email (disposable domains, domains that cannot receive mail, mail servers classified as burner mail hosts, Gmail dot and +tag aliases, the same inbox checked again) and, on paid plans, the IP (datacenter, VPN, Tor, hijacked networks). It is built for AI apps whose free credits get farmed with throwaway accounts. ## Pages - [Docs](https://signupbouncer.com/docs): Supabase install, Ory install, REST API, Rules API, code per stack, testing, reason codes, shadow and enforce, MCP, data handling - [Guides](https://signupbouncer.com/guides): how-to articles, listed under Guides below - [Sign up](https://signupbouncer.com/signup): a free account with an email address and a password, no card. You create API keys per app on the dashboard - [OpenAPI](https://signupbouncer.com/openapi.json): the REST API as an OpenAPI 3.1 document - [Pricing](https://signupbouncer.com/pricing): plans and limits - [Disposable email checker](https://signupbouncer.com/disposable-email-checker): check one email (and IP) in the browser, no account. What each check looks at, the one API call for a signup flow, and answers to common questions - [Signup audit](https://signupbouncer.com/audit): check an app's existing users without installing anything. Run one SQL query (Supabase, Postgres, MySQL) or paste a list of addresses. You send only email domains and counts, and the answer is how many accounts are on burner domains or repeat the same Gmail inbox - [Better Auth plugin](https://signupbouncer.com/better-auth): the @signupbouncer/better-auth plugin (npm and JSR). What it refuses, install and config, what a refused user sees, OAuth signups, shadow mode, and what happens when SignupBouncer is slow or down - [Burner domains](https://signupbouncer.com/burner/): disposable do

{ "openapi": "3.1.0", "info": { "title": "SignupBouncer API", "version": "1.0.0", "summary": "Check a new signup's email address and IP before you create the user.", "description": "Get a key at https://signupbouncer.com/signup (the Free plan needs no card). Call POST /v1/check from your server with a timeout of about 1.5 seconds, act on `action`, and let the signup through when the call fails. Docs: https://signupbouncer.com/docs. Code per stack: https://signupbouncer.com/do