Quickstart
Updated 2026-10-07
What a check is
A check reads public DNS for a domain you name and returns a structured result. No email is sent.
Try it in the browser
Every tool page has a free browser check: enter a domain and read the result in the page. It is rate limited and does not store the domains you enter. Browse the catalog to see what each tool reports.
The API
Requests are paid per call with x402 in USDC on Base, so no account or API key is needed; see payments. A request is a plain GET:
GET https://api.probekit.dev/v1/mail/spf?domain=example.com
The response has four parts:
status: the overall outcome of the check.data: the result of the check, specific to the tool.findings: a list of coded observations, each with a message.meta: when the answer was observed, how long it is fresh and whether it came from cache. See freshness.
Errors use a common format, described in errors. Prices are on the pricing page.