Mail, DNS and web checks

Checks and diagnostics for developers and AI agents.

Check SPF, DMARC, DKIM, MTA-STS, DNSSEC and more, with results that explain what was found and why. Run a free browser check on any tool page. The pay-per-request API works without account or subscription.

Browse tools View quickstart

Pay per request with x402 in USDC. Read the API reference.

GET/v1/mail/check?domain=example.com

{
  "endpoint": "mail.check",
  "status": "warning",
  "data": { "mx": {…}, "spf": {…}, "dmarc": {…} },
  "findings": [
    { "code": "DMARC_POLICY_NONE", "severity": "info" },
    { "code": "SPF_NEUTRAL_ALL", "severity": "warning" }
  ],
  "meta": { "cache_hit": false }
}

Illustrative response shape.

Audit email configuration

SPF lookup budgets, DMARC policy and alignment, DKIM keys and null MX, with findings you can act on.

Inspect domains and DNS

Selected record types with TTL, the resolver that answered and when it was observed.

Integrate checks into agents

Stable finding codes are published today. JSON schemas and a machine-readable description, built from the same registry as these pages, will arrive with the API.

How it works

1
Choose a tool
Every tool documents its inputs, limits and findings.
2
Review the price
A fixed price per check, or per item in bulk, shown before you pay.
3
Get structured results
Status, data and explained findings with evidence and freshness.

Popular tools

All tools →

DNS

CAA record check

Show which certificate authorities may issue for a domain, from its CAA records.

GET /v1/dns/caa$0.01 DNS

DNSSEC check

Report whether a domain is DNSSEC-signed and validates, from the resolvers' AD flag.

GET /v1/dns/dnssec$0.01 DNS

DNS lookup

Resolve selected record types with TTL and the resolver that answered.

GET /v1/dns/lookup$0.005 Domains

Domain health check

One report on a domain's mail and DNS security: nine checks with coded findings.

GET /v1/domain/health$0.08 Domains

RDAP domain lookup

Look up a domain's registrar, expiry date, EPP statuses and nameservers over RDAP.

GET /v1/domain/rdap$0.01 HTTP

Security headers check

Check HTTP to HTTPS redirects, HSTS, CSP and the other security headers of a site.

GET /v1/http/security-headers$0.01 Mail

BIMI record check

Check a domain's BIMI record, its logo and certificate URLs, and DMARC enforcement.

GET /v1/mail/bimi$0.01 MailBulk up to 20

Mail configuration check

One report covering MX, SPF, DMARC and DKIM for known selectors.

GET /v1/mail/check$0.03 Mail

DKIM record check

Check the DKIM public key record for a given selector.

GET /v1/mail/dkim$0.01 Mail

DKIM selector finder

Try 27 common DKIM selectors for a domain and check every key that is found.

GET /v1/mail/dkim-discover$0.02 Mail

DMARC check

Look up and explain a domain's DMARC policy and tags.

GET /v1/mail/dmarc$0.01 Mail

MTA-STS and TLS-RPT check

Check the MTA-STS record and policy file, MX coverage, and the TLS-RPT record.

GET /v1/mail/mta-sts$0.02 Mail

MX lookup

List a domain's mail servers with priorities, including null MX.

GET /v1/mail/mx$0.01 Mail

Mail provider detection

Name the mailbox provider, gateways and sending services a domain uses, from MX and SPF.

GET /v1/mail/provider$0.005 Mail

Reverse DNS check for mail servers

Check PTR records and forward confirmation (FCrDNS) for a domain's MX addresses.

GET /v1/mail/ptr$0.01 Mail

SPF check

Parse and evaluate a domain's SPF policy, including the DNS lookup budget.

GET /v1/mail/spf$0.01 Sites

Site health check

One report on a site's TLS certificate, HTTPS redirects, security headers and domain expiry.

GET /v1/site/health$0.025 TLS

TLS certificate check

Check the certificate a domain serves on port 443: expiry, name, chain and key.

GET /v1/tls/certificate$0.01

Quickstart

# A request without payment gets 402 Payment Required with the exact price.
curl -i "https://api.lookproof.dev/v1/mail/spf?domain=example.com

The 402 response names the price and how to pay before anything runs, and x402 clients can pay and retry automatically. Read the quickstart.