SSL certificate expiry monitoring
An expired certificate takes a site offline for every browser at once. Find out weeks ahead, not from your users.
What each check does
- Connects to the host on port 443 and reads the certificate it presents.
- Records the issuer and the expiry date, and checks that the chain is trusted.
When it alerts
- A warning 14 days before expiry, and again at 7, 3 and 1 day left.
- An incident when the certificate has expired or is not trusted, for example self-signed or missing an intermediate.
- A host that cannot be reached is reported as an error, not as a certificate alert.
example.comGood to know
- Check every hour, every 6 hours (the default) or once a day; each check uses one credit.
- Available on Lite and above.
On every monitor
- Alerts by email, Slack, Discord, Teams, Telegram, PagerDuty, webhooks, Lark, ntfy and the mobile app.
- Recovery thresholds, so an incident closes only after the service has answered several times in a row.
- Dependencies: a monitor that depends on another stays quiet while that one is down.
- Maintenance windows, incident history and public status pages built from the same monitors.
Available from the Lite plan
Lite costs $5 a month for 50 monitors checked every minute, with every alert channel.
Questions
My certificate renews automatically. Do I still need this?
Automatic renewal fails more often than people expect: a changed DNS record, a blocked challenge path, a full disk or a server that never reloads the new certificate. Monitoring tells you when renewal did not happen.
Does the website monitor not catch this already?
It catches an expired certificate when it breaks the site, which is too late. The certificate monitor warns you two weeks before.
How do I check a certificate once?
Use the free tools to look up a certificate on demand; add a monitor to have it checked on a schedule.
SSL 证书到期监控
证书一过期，所有浏览器都会同时打不开网站。提前几周知道，而不是等用户来告诉你。
每次检查做什么
- 连接主机的 443 端口，读取它提供的证书。
- 记录签发者和到期时间，并检查证书链是否受信任。
什么时候告警
- 到期前 14 天提醒一次，剩 7 天、3 天和 1 天时再各提醒一次。
- 证书已过期或不受信任（例如自签名或缺少中间证书）时开启故障。
- 主机无法连接时会报告为错误，而不是证书告警。
example.com使用说明
- 每小时、每 6 小时（默认）或每天检查一次；每次检查消耗 1 个额度。
- Lite 及以上套餐可用。
所有监控通用
- 通过邮件、Slack、Discord、Teams、Telegram、PagerDuty、Webhook、飞书、ntfy 和手机 App 告警。
- 可设置恢复阈值，服务连续多次正常后故障才结束。
- 依赖关系：依赖另一个监控的监控，在被依赖方宕机期间不会告警。
- 维护窗口、故障历史，以及由同一组监控生成的公开状态页。
常见问题
我的证书会自动续期，还需要监控吗？
自动续期失败的频率比想象中高：DNS 记录被改了、验证路径被拦截、磁盘满了，或者服务器一直没有重新加载新证书。监控会在续期没有发生时提醒你。
网站监控不是已经能发现这个问题了吗？
它会在证书过期导致网站打不开时发现问题，但那已经太晚了。证书监控会提前两周提醒你。
怎么单独查一次证书？
用免费工具可以随时查询证书；添加监控后会按计划自动检查。