Mailsurity vs DeBounce: Free Disposable Email API
DeBounce runs a free disposable-email checker, a no-auth GET endpoint that's a genuinely free way to test whether a single domain is disposable, alongside Kickbox's open-source list lookup. Mailsurity's free tier runs the same 5-layer detection cascade paid customers get, including an AI fallback and MX-cluster reputation for gray-zone domains a static list hasn't seen yet, so it keeps catching new throwaway domains a one-time free lookup won't.
Quick take
DeBounce
A free disposable email API you can call with no signup at all, a quick way to test whether a single domain is disposable without committing to a paid plan. Beyond that, we haven't verified how it works internally; confirm details on debounce.com.
Mailsurity
Mailsurity's own free disposable email API: 500 free credits, no card required, running the same cascade described above from the first request. That combination gets Mailsurity to 99.4% overall accuracy, at <100ms p99.
Pricing
DeBounce's free disposable email API costs nothing to call directly. Its separate, broader validation product runs on the pay-as-you-go pricing shown below (verified July 2026); check debounce.com/pricing for current rates. Figures below for Mailsurity are its live current prices, not estimates.
DeBounce
Free disposable-check API, no signup mentioned
Pay-as-you-go, from ~$0.00045/check (credit-based, never expires); 100 free credits at signup, no card required
≈ $0.45 per 1,000 checks*
Mailsurity
500 free credits, no card required
$5/mo on Starter ≈ $1.00 per 1,000 checks*
Starter
$5 / month
5,000 checks / month
Growth
$19 / month
25,000 checks / month
Scale
$59 / month
100,000 checks / month
* Cost-per-1,000 assumes the full monthly credit allotment gets used. Unused Mailsurity credits don't roll over, so the effective rate is higher below full utilization.
Prices shown are Mailsurity's current live plans (see /pricing for the full breakdown, including annual billing); verified July 2026. DeBounce figures reflect only what our own research verified against debounce.com/pricing and its free disposable email API docs. Confirm current details before deciding, since vendor pricing can change.
Feature comparison
Free tier
Mailsurity: 500 free credits, no card required
DeBounce: Free disposable-check API, no signup mentioned
Real-time check API
Mailsurity: Yes, <100ms p99
DeBounce: Yes, a no-auth GET endpoint, ~50ms response
Detection method
Mailsurity: 5-layer cascade: per-team rules -> static legit-list -> 220k+ domain list -> cached AI verdict -> live heuristics/LLM for gray-zone domains
DeBounce: Returns true/false in ~50ms; how it decides isn't published
Catches domains before they're on any list
Mailsurity: Yes, AI fallback (AI double-check on unclear domains, verdict cached 30 days) plus MX-cluster reputation, which flags a new domain sharing a mail server with a known throwaway host before that domain is on any list
DeBounce: Live-tested: flags mailinator.com, guerrillamail.com, and yopmail.com as disposable, but returned false for a domain we made up on the spot — consistent with list-based matching, not live discovery of brand-new throwaway infrastructure
Team controls & bulk workflows
Mailsurity: Yes, per-team allow/deny rules, plus dashboard bulk CSV upload with an enriched results file
DeBounce: The free endpoint is a single-domain lookup only; whether its separate paid product has these isn't published beyond pricing
The “Catches domains…” row above reflects a live test we ran against DeBounce's free endpoint (see the FAQ for the full method). Where DeBounce's column says a capability “isn't published,” that reflects the limits of our own research, not a claim that DeBounce lacks it. Confirm specifics on debounce.com.
Integration: no SDK required
The entire Mailsurity integration is one authenticated POST with plain fetch. No client library required.
curl -X POST https://www.mailsurity.com/api/check-email \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{"email": "user@mailinator.com"}'Full request/response schema, error codes, and code samples in eight languages: see the API reference.
Why a list-based disposable check misses domains
A free lookup like DeBounce's is a solid way to spot-check a single domain against a known-disposable list. The tradeoff any list-based check shares is timing: a brand-new throwaway domain has to be discovered and added to a list before that check can catch it.
Mailsurity layers MX-cluster reputation and an AI fallback on top of its own 220k+ domain list, so a domain can get flagged on its first request, before it's ever been added to any list. MX-cluster reputation works because many throwaway services reuse the same handful of mail servers, so a brand-new domain pointing at a known throwaway host is suspect immediately. See the full 5-layer detection cascade for how each layer works.
Which one should you use?
Pick DeBounce if…
You just need to spot-check whether one domain is disposable: a manual lookup or a lightweight script hitting its free endpoint.
Pick Mailsurity if…
You're checking real signups in production and want per-team allow/deny rules, an AI fallback for domains no static list has seen yet, MX-cluster reputation, and bulk CSV cleanup, all in one API.
Why teams pick Mailsurity over a single free-check endpoint
220k+ tracked domains
A constantly updated disposable-domain list, sourced from public feeds and live throwaway providers.
AI catches what the list hasn't seen yet
MX-cluster reputation and an AI fallback flag brand-new disposable domains before any static list catches up.
Fast enough for the signup path
<100ms p99 latency, so a check can run inline on signup without slowing anyone down.
FAQ
Is DeBounce's free disposable-email checker accurate enough for production signups?
DeBounce's free endpoint (disposable.debounce.io) responds in about 50ms and returns a documented 429 if you're rate-limited, though the exact limit isn't publicly disclosed. We live-tested it directly: it flags long-established throwaway domains correctly, but a domain we invented on the spot came back not-disposable, suggesting it doesn't discover brand-new throwaway infrastructure on its own (see the next question). Confirm current behavior on debounce.com. What we can say is what Mailsurity adds on top of any single-endpoint lookup: an AI fallback and MX-cluster reputation for domains no static list has caught yet.
Does DeBounce catch brand-new disposable domains before they land on a list?
We tested this directly in July 2026: DeBounce's free endpoint correctly flags mailinator.com, guerrillamail.com, and yopmail.com as disposable, but returned false for a domain we made up on the spot that has never been used for disposable email. A single test can't rule out other methods, but it's consistent with list-based matching rather than live discovery of brand-new throwaway infrastructure. Mailsurity's cascade adds a step for that gap: when a domain is new enough that no static list has caught it yet, MX-cluster reputation and an AI classifier can still flag it.
Is Mailsurity's free tier comparable to DeBounce's free disposable-email checker?
They're not quite the same thing. DeBounce's endpoint is a no-auth GET you can call directly, no signup mentioned in what we could verify. Mailsurity's free disposable email API works differently: 500 credits after a no-card signup, run through the same detection cascade paid customers use — per-team rules, a legit-list, the 220k+ domain list, cached AI verdicts, and live heuristics/LLM for gray-zone cases. If you're wiring disposable checks into a real signup funnel rather than testing one address at a time, that's what the free tier is for.
What does DeBounce's paid product cost?
Its broader email-validation product runs on a pay-as-you-go credit system: about $0.00045 per check (≈ $0.45 per 1,000), 100 free credits at signup with no card required, and volume packages from 5,000 up to 5 million credits that never expire (per debounce.com/pricing, verified July 2026). Mailsurity's pricing is live on this page, pulled straight from our current plans (see the pricing section above).
Want the request/response details? The API reference covers authentication, the check-email endpoint, and code samples in eight languages.
See how many of your signups are disposable, free
Paste your signup emails or domains and get an instant count: no signup, no card. Then start free on Mailsurity with 500 credits to try the full detection cascade yourself.