What are the verification methods?

Free widget (no account required):

When the widget is used without a siteKey, it performs a real-time check against check.verifyswift.com directly. No account or credits are required. Checks syntax, MX records, known disposable providers, and relay services. Results are cached in memory for the current browser session so the same address is not re-checked while the page is open.

• • No credits charged, no results logged to your dashboard
• • Returns safe or invalid only — no SMTP handshake
• • Attribution badge (“Email verification by VerifySwift”) is shown beneath the field

Fast Check — integration (0.5 credits):

The same real-time checks as the free widget (syntax, MX, disposable, relay), but routed through your integration endpoint. Results are logged to your dashboard, your integration’s rules apply, and credits are deducted. No SMTP connection is made.

• • Returns safe or invalid — no unknown result
• • 0.5 credits per check; widget and PHP loader do not share a result cache
• • Duplicate submissions within 5 seconds on the same integration are deduplicated (no extra charge). When an active blocking rule is present (e.g. blockFree: true), deduplication is bypassed so rule changes take effect immediately.

Deep Verification — integration (1 credit):

Performs a full SMTP handshake with the recipient mail server to confirm the mailbox exists and can receive mail. The most accurate method available.

• • Returns safe, invalid, or unknown (catch-all domains)
• • Results cached per email address for 10 seconds — the widget check and PHP loader check within that window share one credit. When an active blocking rule is present (e.g. blockFree: true), the cache is bypassed so rule changes take effect immediately. Your account’s custom rules are always re-evaluated even on a cache hit, so no extra SMTP charge is incurred.
• • Recommended when list quality is critical

Send to Verify — integration:

Visitors receive a unique proxy address (@s2v.verifyswift.com). Once they email it, VerifySwift confirms delivery and marks them as verified. Proves ownership of the address, not just its deliverability.

• • Ideal for high-value sign-up flows where proof of access is required
• • The widget polls automatically until confirmation arrives, then unlocks form submission
• • No SMTP check is run on the submitted address itself

Dashboard & Bulk Upload (1 credit per email):

Verify individual addresses or upload a CSV list directly from the dashboard. Uses Deep Verification. All results appear on your Results page and can be filtered and exported.

API (1 credit per call):

Use your API key to verify addresses programmatically via GET /api/verify. Returns the full Deep Verification response including SMTP, syntax, and miscellaneous fields. See How can I use the API? for endpoint details.