Defaults.Exposed › Compare › Typical single-purpose checker
The best free domain security checker in 2026 (and how to choose)
The best free domain security checker is the one that tells you, in plain language, how exposed your domain is and what to fix first. Most free tools test a single layer — email authentication, or HTTP headers, or TLS. Defaults.Exposed grades all of them at once into one A–F score, free, with a percentile and per-failure fixes.
Feature comparison
| Feature | Defaults.Exposed | Typical single-purpose checker |
|---|---|---|
| Covers email auth, TLS, web and DNS | Yes — all four | Usually one layer |
| Single A–F grade | Yes | Rarely |
| Percentile vs a domain population | Yes | No |
| Plain-English fixes for non-experts | Yes | Varies |
| Per-host setup steps | Yes (12 providers) | Varies |
| Private, owner-verified result | Yes | Often open lookups |
| EU data processing | Yes | Varies |
| Price | Free | Free / freemium |
Comparison reflects publicly documented features at time of writing; tools change, so check each vendor for the latest. We compare capabilities only and never publish any organisation's per-domain grade.
How to choose a free domain security checker
There are plenty of good free tools. The honest answer is that the best one depends on what you need:
- Just debugging DNS or mail flow? A diagnostic suite like MXToolbox is excellent — see Defaults.Exposed vs MXToolbox.
- Only care about web headers? A focused header grader like SecurityHeaders.com does that one job well — see Defaults.Exposed vs SecurityHeaders.com.
- Focused on getting email authentication to enforcement? An email-auth platform like EasyDMARC is built for it — see Defaults.Exposed vs EasyDMARC.
The trap is testing one layer and assuming the rest is fine. A perfect header score won’t stop your email being spoofed; flawless DMARC won’t fix an expired certificate.
Why a unified grade wins for most owners
If you just want to know how secure your domain is and what to fix first, Defaults.Exposed grades email authentication, TLS, web headers and DNS together into a single A–F score — free. You also get a percentile against millions of graded domains, a plain-English explanation of every failure, and the exact steps to fix it on your host. It’s a private, owner-verified check, with data processed in the EU.
Start with the grade, fix the biggest gap, and re-check. That’s the fastest route from “I think we’re fine” to actually being fine.
Frequently asked questions
What should a free domain security checker actually test?
At minimum: email authentication (SPF, DKIM, DMARC), TLS and certificate validity, HTTP security headers, and core DNS protections like DNSSEC and CAA. Many free tools cover only one of these, which can leave you feeling protected while a whole category is wide open.
Why does a single grade help?
Because separate pass/fail results for a dozen checks are hard to prioritise. One A–F grade plus a percentile tells you instantly whether you're in good shape or not, and the per-failure fixes tell you what to do first.
Is a free checker enough, or do I need a paid tool?
For knowing where you stand and fixing the basics, a good free check is enough — the fixes themselves (editing DNS records, adding headers) are always free. Paid tools earn their keep with ongoing monitoring across many domains. Start free, then decide.
How do I check my domain without exposing it publicly?
Use a checker that verifies you control the domain before showing its full grade. Defaults.Exposed emails a one-time code to an address at your domain, so only the owner sees the detailed result.
See your own domain graded A–F across every check in one place — privately, free, owner-only. Run the free check →