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API · /mtasts-api

MTA-STS API

healthy 4,404 Subscribers

Inspect a domain's SMTP transport-security posture — whether mail servers are required to deliver inbound mail over authenticated TLS, protecting it from downgrade and man-in-the-middle attacks. Pass a domain and the service fetches the MTA-STS policy file from mta-sts.<domain>/.well-known/mta-sts.txt (its version, mode, the permitted MX hosts and max_age), the _mta-sts DNS TXT record (its policy id) and the _smtp._tls TLS-RPT record (the rua reporting address), then reports whether MTA-STS is actually enforced and a prioritised list of issues — no policy file, no DNS record, a mode of only "testing", or a missing TLS-RPT record. A second endpoint returns just the parsed policy file. The request is made server-side and private/internal targets are refused (SSRF-guarded). Built for email-deliverability and anti-downgrade-attack audits, vendor and third-party assessment, and compliance. An MTA-STS / TLS-RPT checker — the SMTP transport-security counterpart to the email-authentication analyzer (emailsec, which covers SPF, DKIM and DMARC), and distinct from raw DNS lookup (dns). No upstream key, no cache.

#mta-sts #tls-rpt #email-security #smtp #security #dns
api.oanor.com/mtasts-api
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Machine-readable spec so AI agents can integrate this API.

/api/mtasts-api/openapi.json
/api/mtasts-api/llms.txt

Discovery: GET /api/index.json lists every API.

API health

healthy
Uptime
100.00%
Server probes · 24h
Avg latency
118 ms
Server probes · 24h
Subscribers
4,404
active
Total calls
0
last 7 days
status Full status page → · 3 probes/24h

Pricing

Pick a tier — billed monthly, cancel anytime.

Free

Free

  • 2,180 calls / month
  • 2 requests / second
  • Hard cap (429 above quota, no overage)
  • 2,180 calls/month
  • 2 req/sec
  • Policy + DNS + TLS-RPT
  • No credit card
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Starter

€6.40 /month

  • 42,500 calls / month
  • 8 requests / second
  • Hard cap (429 above quota, no overage)
  • 42.5k calls/month
  • 8 req/sec
  • Enforcement + issues
  • Email support
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Pro

€20.70 /month

  • 222,000 calls / month
  • 20 requests / second
  • Hard cap (429 above quota, no overage)
  • 222k calls/month
  • 20 req/sec
  • Deliverability & audit apps
  • Priority support
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Mega

€54.00 /month

  • 835,000 calls / month
  • 50 requests / second
  • Hard cap (429 above quota, no overage)
  • 835k calls/month
  • 50 req/sec
  • Email-security monitoring scale
  • Dedicated SLA
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Related APIs

Other APIs with overlapping tags.

Email Security API

Inspect any domain's email-authentication posture — its protection against spoofing and phishing — via live DNS. Pass a domain and the service looks up and validates SPF (the v=spf1 record, its all-qualifier and the 10-lookup limit), DMARC (the _dmarc policy p=none/quarantine/reject, plus sp, pct and rua/ruf reporting addresses), DKIM (probing the common selectors at selector._domainkey, or pass your own), BIMI and the MX servers — then returns an A+-to-F grade with a prioritised list of issues and concrete advice. A second endpoint parses the DMARC record tag by tag with a plain-English interpretation of the policy. Built for email-deliverability and anti-spoofing audits, vendor and third-party risk assessment, security onboarding and continuous monitoring. An email-authentication analyzer — distinct from mailbox/address validation (email), raw DNS record lookup (dns) and the HTTP security-header grader (secheaders). Pure live DNS, no upstream key, no cache.

api.oanor.com/emailsec-api

OIDC Discovery API

Inspect any OpenID Connect / OAuth 2.0 provider. Pass an issuer (a domain, an issuer URL, or the full discovery URL) and the service fetches the provider's discovery document at /.well-known/openid-configuration, parses every endpoint — authorization, token, userinfo, jwks, registration, end-session, introspection, revocation and device-authorization — together with the supported scopes, response types, grant types, ID-token signing algorithms, PKCE methods and claims, then fetches the JWKS and summarises its signing keys (count, algorithms, key types and key IDs), and reports a validity check with any issues. A second endpoint fetches and summarises any JSON Web Key Set on its own. The request is made server-side and private/internal targets are refused (SSRF-guarded). Built for SSO and OAuth/OIDC integration, identity-provider configuration debugging (Auth0, Okta, Keycloak, Azure AD, Google), security review and monitoring of signing-key rotation. An OIDC discovery / JWKS inspector — distinct from the JWT toolkit (jwt), the security.txt parser (securitytxt) and the HTTP security-header grader (secheaders). No upstream key, no cache.

api.oanor.com/oidc-api

Subresource Integrity API

Generate Subresource Integrity (SRI) hashes for any web asset, so browsers can verify that a CDN-hosted script or stylesheet has not been tampered with. Pass a URL and the service fetches the asset and returns its sha256, sha384 and sha512 SRI hashes, the chosen integrity value (sha384 by default, or pass your preferred algorithm), the asset's size and content type, and a ready-to-paste <script> or <link> tag complete with the integrity and crossorigin attributes. A verify endpoint re-fetches the asset and tells you whether it still matches a known integrity string — catching silent CDN changes or supply-chain tampering before your users hit them. The request is made server-side; private and internal targets are refused (SSRF-guarded). Built for securing third-party scripts, supply-chain hardening, build pipelines and CSP/SRI compliance. A Subresource Integrity generator and verifier — distinct from raw cryptographic hashing of input data (hash), the HTTP security-header grader (secheaders) and the SSL/TLS certificate check (sslcheck). No upstream key, no cache.

api.oanor.com/sri-api

Vulnerability Intelligence API

Prioritise CVEs by real-world exploitation risk — not just severity. Combines the FIRST.org EPSS score (the probability, 0 to 1, that a CVE will be exploited in the next 30 days, with its percentile rank) and the CISA KEV catalog (vulnerabilities confirmed to be actively exploited in the wild — with the vendor, product, date added, remediation due date and whether the flaw is used in ransomware campaigns), and derives a single priority level for each CVE. Look up to 25 CVEs in one call, browse the full CISA Known Exploited Vulnerabilities catalog filtered by vendor, product or ransomware use, or list the CVEs with the highest current EPSS scores. Built for vulnerability management, patch prioritisation, risk scoring and security dashboards — answering not "how bad could this be?" but "how likely is it to actually be exploited?". A vulnerability-prioritisation layer — distinct from raw CVE details and CVSS severity (cve), password-breach checks (pwned) and the HTTP security-header grader (secheaders). Data live from FIRST.org and CISA. No upstream key, no cache.

api.oanor.com/vulnintel-api

Frequently asked questions

Quick answers about pricing, quotas, and integration.

How do I get an API key for MTA-STS API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call MTA-STS API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for MTA-STS API?
Free tier allows 1 request per second. Paid plans scale up to 50 requests per second on the Mega tier. Hard limits return HTTP 429 above the quota — no surprise overage charges.
How much does MTA-STS API cost?
MTA-STS API has a free tier with 100 calls / month. Paid plans start at €6.40 / month with higher quotas and faster rate limits.
Can I cancel my subscription anytime?
Yes. Plans are billed monthly and you can cancel anytime from your billing dashboard. No long-term contracts and no cancellation fee.
Is MTA-STS API GDPR-compliant?
All requests to MTA-STS API go through our EU-based gateway. Your upstream API key never leaves our server and no personal data is shared with the upstream provider beyond the request you send.

Pick an endpoint from the list on the left to see its details and try it.

Code snippets

Sign up to get an API key, then call any path under your slug.

curl https://api.oanor.com/mtasts-api/SOME_PATH \
  -H "x-oanor-key: oanor_test_..."
const res = await fetch("https://api.oanor.com/mtasts-api/SOME_PATH", {
  headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();
$ch = curl_init("https://api.oanor.com/mtasts-api/SOME_PATH");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
$response = curl_exec($ch);
import requests
r = requests.get(
    "https://api.oanor.com/mtasts-api/SOME_PATH",
    headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())

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