Monitors
Every monitor type Telescope offers, and how to pick the right one for what you're watching.
A monitor watches one thing and tells you whether it's healthy. Every type runs on the same schedule you set and feeds the same alerts — they differ only in what they check.
Which monitor should I use?
| I want to know… | Use |
|---|---|
| Is my website or API up, and how fast? | HTTP |
| Does a page contain (or not contain) specific text? | Keyword |
| Is my SSL certificate valid and not about to expire? | SSL |
| Is my domain registration about to lapse? | Domain |
| Is my domain on an email/spam blacklist? | Blacklist |
| Did my cron job or background worker actually run? | Heartbeat |
| Is a host reachable on the network? | Ping |
| Are my DNS records correct and resolving? | DNS |
| Is my mail server accepting connections? | SMTP · POP3 · IMAP |
| Is my site fast enough for users and SEO? | PageSpeed |
All monitor types
Web & API
- HTTP — request an endpoint, measure response time, and classify up / down / degraded (including WAF-blocking detection).
- Keyword — an HTTP check that also asserts a page does, or doesn't, contain specific text.
- PageSpeed — track Lighthouse scores and Core Web Vitals via Google PageSpeed Insights.
Certificates & domains
- SSL — watch a certificate for expiry, validity, and configuration problems.
- Domain — watch a domain registration for expiry and WHOIS/RDAP changes.
- Blacklist — watch your domain's reputation across DNS blacklists (Spamhaus, SURBL, SpamCop).
Cron & network
- Heartbeat — passive monitoring for scheduled jobs: your job pings Telescope, and you're alerted if it ever stops.
- Ping — host reachability and latency over ICMP, with a TCP fallback.
- DNS — verify DNS records, resolver behavior, and expected-value matches.
Email servers
- SMTP — mail-server handshake health and TLS capability.
- POP3 — mailbox-retrieval handshake health and TLS/STLS capability.
- IMAP — mailbox-service handshake health and TLS/STARTTLS capability.
What every monitor shares
- A check interval you choose — how often Telescope runs the check.
- A status of up, down, or degraded, updated on every check (see Core concepts).
- Alerts when it crosses your failure threshold, and a recovery alert when it's healthy again.