A port scanner checks which TCP ports a host is listening on. Open ports map directly to running services — 22 for SSH, 80/443 for web, 3306 for MySQL — so a quick scan reveals attack surface, misconfigured firewalls and forgotten daemons. Enter a hostname or IP and the tool probes the most common ports, then reports each as open, closed or filtered. Only scan systems you own or have written permission to test; unauthorized scanning can break terms of service or local law.
How to use Port Scanner
1
Enter the target
Type or paste the target you want to inspect into the input field at the top of the page.
2
Run the Check
Click the check button — the tool queries live data sources and returns results in seconds.
3
Read the Report
Review each finding: status, score, and the reason behind every warning are listed line by line.
4
Act on the Findings
Follow the linked remediation guides to fix issues, or copy the report to share with your team.
Why Use Port Scanner
When something in your stack misbehaves, half the battle is figuring out whether the problem is you, the network, or the other side. Port Scanner gives you a fast, opinionated readout so you can rule things in and out in seconds. Because the check runs on live infrastructure and reports raw results — not marketing-safe summaries — you can trust what you see and act on it. Toolzer's design philosophy is simple: privacy-first (no tracking, no accounts), performance-first (the page is interactive in under a second on a 3G connection), and honesty-first (no fake ratings, no dark patterns, no upsells). Port Scanner follows the same rules as every other utility on the site. You can bookmark this page, share the URL with a colleague, or pin it to your browser's toolbar — the experience will be identical every visit, and it will keep working even if you're on airplane Wi-Fi. Real people use this tool for real work — freelancers cleaning up client deliverables, sysadmins triaging tickets, students finishing assignments — and it is tuned for those workflows, not for demo videos.
Tips & Best Practices
1Run the check from more than one network (mobile hotspot vs office) to distinguish a real outage from a local DNS issue.
2Save the full report with a timestamp — it is invaluable evidence when opening a support ticket with a provider.
3Re-run the check after every fix so you have a clean 'before / after' record.
4Cross-reference results with a second, independent tool when the stakes are high — no single source is perfect.
5If the check surfaces a warning you don't understand, read the linked docs before applying a 'fix' someone suggested online.
Common Use Cases
1Diagnosing a slow or unreachable website before opening a support ticket with your ISP or hosting provider using Port Scanner.
2Verifying that a newly configured DNS, firewall, or VPN rule actually took effect from the public internet.
3Auditing a client's infrastructure during a freelance networking or security engagement.
4Teaching students or junior admins how core internet plumbing (IP, DNS, routing) works with a live example.
5Sharing precise technical evidence (IP, hostname, response times) with a remote colleague inside a chat message.
Frequently asked questions
Is scanning my own server safe?
Yes. Lightweight TCP connects are how legitimate health checks work. Avoid heavy or repeated scans against shared infrastructure.
Difference between closed and filtered?
Closed means the host actively refused the connection. Filtered means a firewall silently dropped the packet — usually a stronger security posture.
Which ports should never be public?
Database ports (3306, 5432, 27017), SMB (445), RDP (3389) and Redis (6379) should be firewalled or restricted to a VPN.
Why is my open port not reachable from outside?
Likely NAT or a cloud security group. Local firewall says open; the upstream router or VPC rule still blocks inbound traffic.
Do I need to create an account to use Toolzer?
No. Every utility on Toolzer is free, anonymous, and works in any modern browser without registration.
Is Toolzer safe to use with sensitive inputs?
Yes. Whenever the tool can produce an answer entirely in the browser, the data never leaves your device.
Does Toolzer work on mobile?
Yes. The interface is fully responsive and works on iOS Safari, Android Chrome, and every modern mobile browser.
Can I link to or bookmark a result?
Yes. Every Toolzer page has a clean permanent URL you can bookmark or share.
