Help Centre

Getting started, common questions, and known limitations.

Getting started

Certline is a TLS certificate inspection tool. You paste a hostname, and we tell you what certificate the server actually presented — not what a cached lookup says, but what a real TLS handshake returns right now.

Go to the check page. You'll see a single input field.
Type a hostname. Any public-facing hostname that speaks TLS on port 443 — example.com, api.example.com, mail.example.org. Optionally specify a custom port.
Press Enter or click Check. Certline opens a real TLS connection, reads the certificate the server sends, and displays the results in plain language.
Read the verdict. The banner tells you at a glance whether the certificate is valid, expired, expiring soon, or has an incomplete chain. Below that, you'll find the expiry date, issuer, subject alternative names, and chain details.

No account needed. No registration. No data stored. Each check is independent.

Frequently asked questions

What exactly does Certline check?

Certline opens a real TLS connection to the hostname you specify (the same way a browser would) and reads the certificate the server presents. We report: the expiry date and days remaining, who issued the certificate, every hostname the certificate covers (subject alternative names / SANs), and whether the server sent a complete certificate chain — including whether the intermediate certificates link together correctly.

Why does chain completeness matter?

A server can send the leaf certificate alone and omit the intermediate certificate that links it to a trusted root. Desktop browsers often mask this because they cache intermediates from prior visits, but mobile clients and fresh browser profiles do not — the site breaks for those users. Certline shows you the chain exactly as the server sends it, so you see the gap before your users do.

Does Certline email me when my certificate is about to expire?

No. Certline does not send email alerts, reminders, or notifications of any kind. There is no email sender in this fleet. Each check is on-demand — you ask, we answer. If you need recurring checks or expiry alerts, that is a feature that would need to be built (or sourced from a monitoring service).

What happens if the server I type is unreachable?

Certline reports that the host did not respond to the TLS handshake, and the check did not complete. We are explicit that this is a connection failure, not a finding about your certificate or server configuration. If the host is behind a firewall, requires a VPN, or does not exist, we say so plainly.

Can I check multiple hostnames at once, or scan a whole domain?

No. Certline checks one hostname at a time. We do not scan IP ranges, enumerate subdomains, or perform bulk lookups. Automated bulk scanning is not permitted under our terms of service. Each check is a single, independent TLS handshake.

Is there an API? Can I integrate Certline into my CI/CD pipeline?

API access is planned as a Pro feature, but Pro is not yet available for purchase. There is no payment processor connected and no account system. When Pro launches, it will include API key–based access for CI/CD integration. For now, the web interface at /app is the only way to use Certline.

Does Certline store my lookups or track my history?

No. There is no account system, no database of past checks, and no history stored. Each check is independent and ephemeral. What the server presents at the moment of the check is what we report, and then it is gone.

Known limitations

Certline is in active development. These are the things that do not work yet, or that we have explicitly chosen not to build:

No monitoring or alerts. Certline does not send email, Slack messages, webhooks, or any other notification. If you want to know when a certificate expires, you need to check manually. There is no email sender configured in this fleet.
No account system. There is no way to create an account, save favourite hosts, or view a history of past checks. Pro features (including API access) are planned but not yet available.
No payment processor. Pro subscriptions cannot be purchased. The checkout on the pricing page is a labelled demo that takes no real payment. See the pricing page for details.
No bulk scanning. One hostname at a time, on demand. Range scanning, subdomain enumeration, and automated bulk lookups are not supported and are prohibited by the terms of service.
Backend dependency. Certline requires a server-side TLS stack to perform checks. If the backend is unavailable, the check page will report an error. This is not a fault of your certificate.
Public hosts only. Certline can only reach hostnames that are publicly accessible from the server. Hosts behind a VPN, private network, or firewall that blocks outbound connections from our server cannot be checked.

How to contact us

Email support is not yet available. There is no mailbox configured for this service. If you encounter a bug or have a question not covered here, your options are:

Check the terms of service for any updates.
Refer to pricing for planned Pro features.
For issues that cannot be resolved from the documentation, the question is escalated to the owner who has access to the infrastructure.

Report a bug. If Certline returns incorrect data for a hostname you can verify independently, please note the hostname, the result you saw, and what you expected. This information helps the owner diagnose the issue. At this stage, there is no bug tracker or ticketing system.