Know before you send.
Wrong guesses damage your sender reputation.
We tell you the real risk on every address — including the ones other tools can’t answer.
No credit card. 100 free verifications — credits never expire.
An unverified address bounces.
Mailbox providers track your bounce rate.
Gmail and Outlook start filtering your mail.
Verify first — the bounce, and the damage, never happen.
For inbox providers, it’s a trust signal. For you, it’s deliverability, replies, and revenue — all downstream of one bad guess.
You send anyway — or drop the address.
Confidently safe to send.
Illustrative example — see /accuracy for real methodology and results.
Your list isn’t our asset.
Hashed by default
Submitted addresses are stored as a keyed HMAC-SHA256 hash and the domain by default — not a bare hash, which would be reversible via a rainbow table given how predictable email formats are. Want a readable record to check later? Turn on plaintext storage in Settings — it's encrypted at rest and off unless you ask for it.
Retention you control
Verification records auto-delete on a schedule you set — 7 days by default, up to 90. Your dashboard history covers the same window. See /dpa for the exact mechanics.
Never sold, never shared
Your data isn't a second revenue stream. We're a processor acting on your instructions (see /dpa), not a data broker.
No trackers on this site
No analytics pixels, no ad trackers, no session recorders — check the network tab if you don't believe us.
Just verification, nothing else
No email finder, no blacklist monitoring, no contact enrichment, no profile-building — we don't append names, job titles, or social profiles to what you submit. What you send is what you get back, plus a verdict.
Infrastructure you don't share
Your verification traffic runs on infrastructure built for one purpose, not pooled across thousands of unrelated customers. No shared reputation, no cross-tenant exposure.
Paste an address, get a verdict.
3 free verifications/day, no signup required
Most tools guess. We don’t.
Some mail servers never give a clean yes-or-no. Every other verifier either charges extra for this case or just returns unknown — same as saying nothing.
Vendor-published benchmark citations, not independent third-party audits — see /accuracy for skink’s own methodology.
Nine real differences, not marketing filler.
Unresolved addresses, resolved
Every incumbent returns unknown on ~15% of B2B addresses
status: risky — some servers accept every address to hide which ones are real. We don't stop at unknown; we tell you how uncertain it is.
Confidence, not a guess
Binary valid/invalid verdicts with no reasoning
confidence: 0.0–1.0 — not yes or no. A number that tells you exactly how much to trust the result.
Protected inboxes, still resolved
Security gateways silently return unknown
A real verdict even when the front door is locked
Exposed reasoning
No explanation for why an address was marked risky or invalid
reasons[] — every result comes with a plain-English reason, not just a code.
Calibration that never stops
Static thresholds that never adapt to your actual bounce data
Verdicts are checked continuously against real delivery outcomes — accuracy compounds instead of decaying
International domain support
Every competitor rejects non-ASCII emails (xn--, IDN, .рф, .中国)
Non-ASCII addresses are normalized and verified the same as any other
Credits that don't expire
Incumbents expire credits and push forced subscriptions
Buy credits once, use them whenever. No 12-month clock.
Honest, not manufactured
Some verifiers rotate IPs or route through proxy pools to force an answer out of a stalling mail server
A stalling server is usually stalling on purpose, to stop spam. We return risky instead of faking a confident valid.
Real accounts only
Disposable-email signups let anyone abuse a shared verifier's reputation
Signups from disposable domains are blocked at the door — every account on this API is a real business.
Buy a pack. Or let it refill itself.
No sales calls either way. 1 credit = 1 verification. Unknown results are free. Resolving ambiguous addresses is included. Credits never expire. Every plan is self-serve — card in, verifying in under a minute.
100 credits, no card required — enough to see real accuracy on your own list before you spend anything.
10,000 credits
$0.0049 / email
Your first real batch. Validate a list before a campaign goes out.
Buy Growth50,000 credits
$0.0039 / email
Monthly list hygiene on autopilot. Our most-bought pack.
Buy Scale200,000 credits
$0.0024 / email
Built for teams running cold outreach at real throughput.
Buy Volume1,000,000 credits
$0.001 / email
The best rate we offer without a sales call. A million credits.
Buy MaxSave a card once — no subscription, no upfront payment.
The pack you chose is repurchased automatically, so verifications never stop.
Every auto refill costs exactly what buying the pack by hand costs. No extra fees.
One click in your dashboard's Billing page — same place you enable it.
Auto top-up means a busy week never hits a wall — your pack refills itself the moment you run dry, at the same price as buying it by hand.
Every inbox provider, recognized automatically.
Every signal, resolved into one calibrated score.
Every address gets checked against multiple independent signals — not just one pass/fail test.
Ambiguous cases get resolved through methods that stay ours — the addresses other tools give up on.
A confidence score reflects real-world risk, not a static model frozen at launch.
Verdicts are continuously checked against real delivery outcomes as they come in.
Reasoning, not just a verdict.
No SDK required — plain HTTPS. Full reference at /docs.
curl -s https://api.skink.dev/v1/verify \
-H "Authorization: Bearer $SKINK_KEY" \
-H "Content-Type: application/json" \
-d '{"email":"jane.doe@acme.com"}'{
"email": "jane.doe@acme.com",
"status": "deliverable",
"confidence": 0.91,
"reasons": [
"Address resolved with high confidence",
"Calibrated against real delivery outcomes"
],
"recommendation": "send"
}One binary check. One calibrated system.
Calibrated confidence isn’t a setting they can flip on — it’s a different system.
| Feature | Incumbents | skink |
|---|---|---|
| Resolves ambiguous addresses | ✕ extra charge or unknown | ✓ included |
| Calibrated confidence | ✕ binary valid/invalid | ✓ calibrated probability |
| Exposed reasoning | ✕ none | ✓ plain-language reasons |
| Credits never expire | ✕ 12mo expiry (most) | ✓ never |
FAQ
Do you store the email addresses I verify?
Not by default. We store a keyed HMAC-SHA256 hash of the address plus the domain — not a bare hash, which would be reversible via a rainbow table. If you want to look up later what you sent and what came back, you can turn on plaintext storage (encrypted at rest) in your dashboard's Settings. Either way, verification records auto-delete on a schedule you control — 7 days by default, up to 90.
Do you charge extra to resolve addresses other tools can't?
No. It's included in every plan, not sold as a premium add-on.
What happens to unused credits?
They never expire. No forced subscription, no use-it-or-lose-it.
What does the confidence score mean?
Higher means more certain. Confidence is continuously checked against real delivery outcomes, not a static model frozen at launch. Calibrated against real labeled outcomes, not vendor marketing percentages.
What if a mailbox server responds slowly or defers the check?
Detected automatically. Set allow_async_followup on your request and we'll retry in the background once the delay clears — poll for the upgraded result instead of re-submitting the address yourself.