Does Certimon offer a public SSL checker API?

Not yet. Certimon currently exposes SSL checks through the Telegram bot and web dashboard rather than a public HTTP API. This keeps the free service simple and avoids API abuse while still covering most teams that only need expiry alerts.

What should an SSL certificate checker API return?

A useful API should return the hostname, port, issuer, subject, SANs, valid-from and valid-until timestamps, days remaining, chain validity, hostname-match status, protocol errors, and a normalized status such as ok, expiring_soon, expired, or invalid.

When is a no-code SSL monitor better than an API?

Use a no-code monitor when the goal is simply to receive certificate expiry alerts. Use an API when you need to enrich an internal asset inventory, run custom compliance reports, or integrate certificate checks into another product.

Can an SSL checker API check a custom port?

Yes, a robust SSL checker API should accept a port parameter because many APIs, admin panels, and internal services terminate TLS on ports other than 443. Certimon's public no-code checks focus on hostnames reachable from the public internet.

SSL checker API · Certificate expiry API · No-code alternative

SSL Checker API: What to Use, What to Build, and When to Skip the API

If you searched for an SSL checker API, you probably need repeatable certificate checks for a list of domains. Certimon does not expose a public API yet — but it does provide free SSL checks and expiry alerts through Telegram and the web dashboard, which is often the simpler answer.

Start free monitoring See API design

Decision: content and no-code monitoring first, public API later

Certimon already performs real TLS handshakes, parses live certificates, and turns expiry data into reminders. For now, that capability is exposed through /check, /remind, /domains, and the web dashboard instead of a public HTTP API.

That decision is intentional. A free public SSL check API attracts high-volume crawlers, port scans, SSRF-style misuse, and noisy retries. Until there is a clear product need for programmatic access, Certimon is better positioned as a free, no-code SSL certificate monitor for operators who want alerts rather than another integration to maintain.

Short version: use Certimon if you want free SSL expiry monitoring and Telegram alerts. Use an API if you need to pipe certificate data into your own inventory, compliance workflow, or customer-facing product.

When you actually need an SSL certificate checker API

An API is useful, but only when the certificate result must feed another system.

API is the right fit

• You maintain an asset inventory and want to enrich each hostname with certificate metadata.
• You need scheduled compliance exports showing issuer, expiry, SAN coverage, and chain validity.
• You are building a product that must check customer domains during onboarding.
• You need to test non-standard TLS ports such as 8443, 9443, or service-specific endpoints.
• Your alerting pipeline already lives in code and expects JSON responses.

No-code monitor is enough

• Your main goal is to avoid expired certificates on websites and APIs.
• You want reminders 30, 7, and 1 day before expiry without writing a cron job.
• You prefer Telegram notifications over storing API tokens and webhook secrets.
• You manage client or side-project domains where a full observability stack is overkill.
• You need a quick backup check separate from Let's Encrypt or Cloudflare automation.

If Certimon adds an SSL check API, this is the shape it should have

A good SSL certificate checker API — including any SSL checker API free tier — needs more than a days-until-expiry number. It should normalize DNS, TCP, TLS, hostname, certificate-chain, and timeout failures into predictable fields so the caller can act on the result.

GET /v1/ssl/check?host=example.com&port=443
Authorization: Bearer certimon_api_key

{
  "host": "example.com",
  "port": 443,
  "checked_at": "2026-05-11T22:00:00Z",
  "status": "ok",
  "days_remaining": 73,
  "valid_from": "2026-04-12T00:00:00Z",
  "valid_until": "2026-07-25T23:59:59Z",
  "issuer": "Let's Encrypt",
  "subject": "CN=example.com",
  "subject_alt_names": ["example.com", "www.example.com"],
  "hostname_matches": true,
  "chain_valid": true,
  "protocol": "TLSv1.3",
  "error": null
}

Endpoint

GET /v1/ssl/check with required host and optional port. Default port should be 443.

Rate limits

Start at roughly 60 checks per minute and 5,000 checks per day per API key, with lower anonymous limits if public trials exist.

Abuse controls

Block private IP ranges, localhost, link-local hosts, suspicious redirects, huge SAN payloads, and ports outside an explicit allowlist.

How Certimon checks certificates without a public API

Certimon connects to the public hostname, performs a real TLS handshake, reads the served certificate, and extracts the expiry date. The same underlying kind of check powers the Telegram commands operators use today.

For a quick one-off check, send /check example.com. For monitoring, send /remind example.com 30 and optionally add /remind example.com 7 and /remind example.com 1. Certimon then sends Telegram reminders when the certificate enters those windows.

Because checks originate from Certimon infrastructure, domains must be reachable from the public internet. If you need to test private hostnames, internal-only services, or arbitrary ports across a network, a self-hosted script or internal API is the safer pattern.

SSL checker API alternatives

Choose based on whether you need data, alerts, or full ownership.

Option	Best for	Trade-off
Certimon Telegram + dashboard	Free expiry alerts, no-code monitoring, simple operator workflow	No public HTTP API yet; public hostnames only
Open-source scripts	Internal networks, custom ports, private compliance needs	You own scheduling, alerting, retries, and maintenance
Observability platforms	SLO reporting, incident routing, enterprise controls	Often overkill or expensive for small domain portfolios
Dedicated public SSL checker APIs	Programmatic enrichment, product onboarding, batch checks	API quotas, token storage, pricing, and abuse-related limits

Need alerts, not another API integration?

Start with Certimon's free no-code SSL monitoring. If a public API becomes the right product move, this page documents the endpoint shape, schema, rate limits, and safety controls to build next.

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