Port monitoring catches what HTTP monitoring can't see.
Port monitoring checks if a specific TCP/UDP port is accepting connections. Compare the best port monitoring tools — free tiers, protocols, and pricing.
Port monitoring (TCP monitoring) checks whether a specific network port is open and accepting connections. It catches failures that HTTP monitoring can't see — a database that stops listening on port 5432, a mail server that drops port 25, a Redis cache that crashes on port 6379, or an SSH daemon that dies on port 22. HTTP monitoring only tells you the web server is up; port monitoring tells you whether the services behind it are reachable.
Most uptime monitors include port monitoring, but the details vary: some offer it on the free tier, some only on paid plans; some restrict free use to non-commercial projects; and the number of free monitors determines how many ports you can watch simultaneously. If you're monitoring a small infrastructure stack (web, database, cache, mail, SSH), you need a tool with enough free monitors to cover each service.
I compared four tools that include port monitoring on their free tiers. Every pricing figure was verified on 3 August 2026 against each vendor's own pricing page.
| Feature | SurePing Our tool | UptimeRobot | Better Stack | StatusCake |
|---|---|---|---|---|
| Port monitoring on free tier | Yes | Yes | Yes | Yes |
| Free monitors (total) | 55 | 50 | 10 | 10 |
| Starting paid price | $10/mo | €13/mo | $24/mo | $20/mo |
| Commercial use on free tier | Yes | No | Yes | Yes |
| Fastest interval (free) | 5 min | 5 min | 3 min | 5 min |
| Multi-region checks | No (single region) | Yes | No (paid only) | Yes |
| Native Slack/Discord integration | Via webhook | Yes | Yes | Yes |
SurePing includes TCP port monitoring on every plan, including Free. You can monitor SMTP, POP3, FTP, database (PostgreSQL, MySQL, Redis), SSH, or any custom TCP port. With 55 free monitors and no commercial-use restriction, you can watch every port in a small infrastructure stack at no cost — web, database, cache, mail, SSH, and more — with room to spare.
The trade-off is single-region checks. For port monitoring, this is less critical than for HTTP monitoring — if a port is open, it's open regardless of where you check from. But if you want multi-region confirmation or native Slack/Discord integration, UptimeRobot is the better fit. SurePing uses webhook-based integrations for alerts.
Best for: solo developers and small teams who want to monitor many TCP ports for free with no commercial-use restriction, and are comfortable with webhook-based alerts.
UptimeRobot's port monitoring is well-established, proven, and widely used. With 50 free monitors, 20+ native integrations (Slack, Discord, Teams, PagerDuty), and multi-region checks, it's the most mature port monitoring option on this list. If you want port failure alerts piped directly into Slack without setting up a webhook, UptimeRobot is the strongest choice.
The non-commercial restriction on the free tier is the main caveat. If you're monitoring ports for a business — production databases, mail servers, SSH daemons — you need a paid plan starting at €13/month. UptimeRobot also defaults to annual billing, so the headline price is lower than the month-to-month cost.
Best for: non-commercial projects that want proven port monitoring with native Slack/Discord integration and multi-region checks.
Better Stack includes port monitoring on its free tier (10 monitors) and ties it into a strong incident management workflow. If a database port goes down, Better Stack can create an incident, page the on-call person, and track resolution — all within the same platform. The 3-minute free-tier interval is the fastest on this list.
The free tier is small (10 monitors) — tight for monitoring multiple ports across a stack. Paid starts at $24/month for 10 monitors, which is more than twice SurePing's entry price. If you only need port alerts (not incident management), SurePing or UptimeRobot are cheaper and offer more free monitors.
Best for: teams who want port monitoring tied into incident management and on-call scheduling, and can work within 10 free monitors or are willing to pay.
StatusCake includes port monitoring on its free tier (10 monitors) alongside SSL certificate monitoring and domain expiration checks. If you want port, SSL, and domain monitoring bundled together, StatusCake is the only tool on this list that offers all three. Multi-region checks are available on the free tier.
The gaps: no cron job monitoring, no free status pages, and the UI feels dated. The 10-monitor free tier is restrictive compared to SurePing's 55 and UptimeRobot's 50. If you need to monitor many ports, the free tier won't stretch far enough.
Best for: teams who want port monitoring bundled with SSL and domain monitoring, and don't need cron job monitoring or a large free tier.
SurePing includes TCP port monitoring on the free tier with 55 monitors and no commercial-use restriction. If you need to monitor many ports — database (5432, 3306, 6379), mail (25, 587, 993), SSH (22), FTP (21), or custom application ports — the 55-monitor free tier gives you plenty of capacity to cover a small infrastructure stack at $0.
The honest trade-off: SurePing runs single-region checks and uses webhook-based rather than native Slack/Discord integration. For port monitoring, single-region is less of a drawback than for HTTP checks — a port is either open or closed regardless of where you check from. But if you want native integrations or multi-region confirmation, UptimeRobot is the better fit. If you want port monitoring tied into incident management, Better Stack is the alternative — at a higher price with fewer free monitors.
Feature availability and pricing verified on 3 August 2026 against each vendor's own pricing page and documentation. Port monitoring features reflect each vendor's published monitor type descriptions as of that date. UptimeRobot pricing was captured for a UK/EU visitor in EUR with monthly billing selected; the page defaults to annual billing. SurePing pricing is in USD. Vendor pricing and features change without notice — confirm current details before committing.
Port monitoring checks whether a specific TCP or UDP port on a server is open and accepting connections. It works at the transport layer (Layer 4) — lower than HTTP — and is useful for monitoring databases, mail servers, SSH, Redis, and other non-HTTP services. If the port is closed or the service crashes, you get alerted.
Yes, with all four tools on this list. SurePing, UptimeRobot, Better Stack, and StatusCake all include port monitoring on their free tiers. SurePing offers the most free monitors (55) with no commercial-use restriction; UptimeRobot offers 50 (non-commercial only); Better Stack and StatusCake offer 10 each.
Common ports to monitor include 22 (SSH), 25 and 587 (SMTP mail), 80 and 443 (HTTP/HTTPS), 3306 (MySQL), 5432 (PostgreSQL), 6379 (Redis), and 993 (IMAP). Monitor any port that a critical service listens on — if the port drops, the service is down even if the host is reachable.
Most uptime monitors — including SurePing, UptimeRobot, Better Stack, and StatusCake — focus on TCP port monitoring, which covers the majority of services (databases, mail, SSH, web). UDP monitoring is less common because UDP is connectionless and harder to probe reliably. Check each vendor's documentation for UDP support if you need it.
Ping monitoring (ICMP) checks whether a host is reachable at the network layer — the server is online and responding at the IP level. Port monitoring (TCP) checks whether a specific service on that host is accepting connections — the database is listening on port 5432. A host can be pingable but have a crashed database, so both types complement each other.