UserCheck is an API aimed at filtering signups, best known for detecting disposable and free email domains. That puts it closer to isBusinessEmail than most email verification tools. If disposable detection is all you need, compare both on your own traffic.
Where isBusinessEmail differs
| isBusinessEmail | |
|---|---|
| Core rule | Business = the company’s own custom domain; personal = a shared-domain provider. Lists plus DNS evidence for everything not on a list. |
| Policies | b2b, strict, lenient map categories to allow / review / block, with a review lane for role accounts and low-evidence domains |
| Explainability | Reason codes for every verdict: MX fingerprints, SPF/DMARC/DKIM, SaaS verification tokens, domain age, parked pages |
| Workspace detection | Google Workspace and Microsoft 365, with Microsoft tenant ID, region, managed vs federated and identity provider |
| Integration readiness | integrations.google_workspace_ready / microsoft_365_ready for onboarding flows |
| Price | Free, with fair-use limits |
For UserCheck’s current features, fields and pricing, check their site; capabilities change and we don’t want to misstate them.
Pick isBusinessEmail if…
- Your product integrates with Google Workspace or Microsoft 365, and you want to know which one a company uses at signup.
- You want an explainable decision to show users and support staff.
- You want a free API with publishable keys for browser hints.
Either way
Test with your real signup data. Run a sample of recent signups through both and compare against what actually happened to those accounts. Our test addresses make it easy to wire things up first, and feedback fixes misses for everyone.