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UFOZoo

Port Scanner Online: Check Open Ports & Common Services

Port scanner online: check which ports are open on a host and which common services use them. Includes security alerts for exposed sensitive ports.

Updated 2026-08-16

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Features

  • Test HTTP/HTTPS port availability on any host via browser fetch
  • Security alerts: auto-warn when sensitive ports (SSH, RDP, databases) are exposed
  • Preset port groups: Basic, Web, Gaming, Malicious, scan with one click
  • Comprehensive port reference with 100+ common ports and their services
  • Quick-test popular web ports: 80, 443, 8080, 8443, 3000, 5000
  • Search and filter ports by number, service name, or protocol
  • Local port detection guides for Windows, macOS, and Linux
  • Copy port list, commands, or individual entries to clipboard
  • Custom port scanning: enter any port number or comma-separated list for targeted testing
  • Detailed service descriptions for each port: understand what the service does and common security implications
  • Port status history: keeps a log of previously scanned ports for each host during your session, allowing you to track changes in port status over time
  • Scan result sharing: copy the complete scan report as formatted text including open ports, status, and security warnings for team collaboration or security audit documentation

How to Use

  1. 1Enter a hostname or IP address in the target field.
  2. 2Click Quick Test to probe common web ports, or click a port group button to scan presets.
  3. 3Review the Security Alerts panel for warnings about exposed sensitive ports.
  4. 4Browse the Port Reference tab to search or filter by port number or service name.
  5. 5Use the Local Guide tab for Windows/macOS/Linux port detection commands.
  6. 6For full TCP port scanning, use local tools like nmap: nmap -p- target.com
  7. 7Use the custom tab to test any specific port; great for verifying firewall rules after configuration changes
  8. 8Check the Security Alerts panel first when scanning unfamiliar hosts to identify immediate risks
  9. 9Refer to the Categories sidebar to browse ports by function (Web, Database, Mail, etc.) for targeted security audits
  10. 10Copy nmap/netcat commands from the Local Guide to run more thorough scans from your own machine
  11. 11Use the malicious port group to scan for known malware backdoor ports; if any respond, the host may be compromised or infected
  12. 12After configuring a new firewall rule, use custom port scanning to verify that the intended ports are open and unintended ports are properly blocked

Frequently Asked Questions

Why can't this tool scan all 65535 ports?

Browsers cannot make raw TCP connections due to security restrictions. This tool uses HTTP fetch to test web-accessible ports only. For full TCP port scanning, use local tools like nmap (nmap -p- target.com) or netcat (nc -zv target.com port).

How do security alerts work?

When scanning detects sensitive ports (SSH, RDP, MySQL, etc.) open to the internet, the tool displays security warnings. These ports are common attack vectors when exposed publicly. Warnings are based on common security risks, not vulnerability scanning.

What are port groups for?

Port groups bundle related ports for one-click batch scanning. Basic contains the most common ports, Web focuses on HTTP/HTTPS, Gaming includes Xbox/PlayStation/Minecraft ports, and Malicious contains known malware ports.

Can this scan UDP ports?

No. Browsers cannot make UDP connections. This tool only tests TCP ports via HTTP fetch. For UDP scanning, use nmap with the -sU flag: nmap -sU target.com

What are the local port detection commands for?

Local commands (netstat, lsof) show ports listening on your computer. This differs from online scanning: online scanners test if ports are accessible from the internet, while local commands show system-level port status.

Is the target server's IP logged?

No. The hostname you enter is used only for fetch requests from your browser. There is no server-side logging, no proxy, and no data storage. However, the target server will see your IP in its access logs, just like visiting any website.

What is the difference between an open and closed port?

An open port means a service is actively listening and accepting connections on that port. A closed port means no service is listening; the host responded but refused the connection. Filtered ports (no response) may indicate a firewall blocking the probe. Open ports on sensitive services (SSH, RDP, databases) should be reviewed carefully for security.

What ports should I check first for security?

The most commonly attacked ports are: 22 (SSH), 23 (Telnet), 25 (SMTP), 53 (DNS), 80 (HTTP), 110 (POP3), 143 (IMAP), 443 (HTTPS), 445 (SMB), 3389 (RDP), 3306 (MySQL), 5432 (PostgreSQL), 6379 (Redis), 8080 (HTTP-alt), and 27017 (MongoDB). The tool's Basic and Malicious port groups cover these. Any of these exposed to the internet without proper security controls presents a risk.

Can I scan ports on my local network?

Yes, you can enter a local IP address like 192.168.1.1 or 10.0.0.1. However, the browser fetch method only checks HTTP/HTTPS ports. For local network scanning, the Local Guide tab provides OS-specific commands (netstat, lsof, nmap) that can detect all listening ports on your local machines without browser limitations.

How do I know if a port scan is legal?

Port scanning public servers without permission may violate the target's terms of service or applicable laws in some jurisdictions. Always ensure you have authorization before scanning systems you do not own. This tool is designed for testing your own servers, verifying firewall configurations, and educational purposes. Unauthorized scanning of third-party networks may be considered a hostile act.

What are the common ports for web services?

Standard web ports: 80 (HTTP), 443 (HTTPS). Common alternatives: 8080 (HTTP-alt), 8443 (HTTPS-alt), 3000 (Dev/Node.js), 5000 (Flask/Dev), 8000 (Python Dev), 8888 (Jupyter). The Web port group in this tool pre-selects these for one-click testing. Many cloud platforms also use 8080 for HTTP and 8443 for HTTPS as default ports.

Why does this port scanner online show a port as closed when the service is definitely running?

The browser only tests whether an HTTP connection can be established, so ports that require raw TCP, like SSH (22), RDP (3389), or MySQL (3306), are reported as closed or unknown even when the service is up. A firewall that silently drops probes also causes false 'closed' results. To verify, run a local scan: nmap -p 22,3389 your-server.com; 'open' there confirms the service is really listening.

Can I scan ports from my phone, or do I need to download a port scanner apk?

No apk or installation is needed; this tool runs in any mobile browser and can test web ports from your phone. For full TCP scans on Android, install Termux and run pkg install nmap. Note that mobile carrier networks often block inbound connections and restrict certain ports, so results from a phone can differ from a wired connection.

This tool vs nmap: which should I use for port scanning?

Different jobs. nmap is the full toolkit: raw TCP/UDP scans of all 65535 ports, service fingerprinting, its script engine, and OS detection. Run it from a machine you control. This tool needs no installation, tests whether common web ports are reachable from the internet in seconds, and works inside locked-down browser environments (e.g., a corporate laptop without admin rights). Typical workflow: quick reachability check with this tool after a firewall change, then nmap from your own server for anything deeper.

Will scanning affect the target server, or will I be detected?

This tool sends a handful of ordinary HTTP requests per check, indistinguishable from normal browsing, so it will not load the target meaningfully or trip alarms. What does get noticed: full-port scans with tools like nmap, which can trigger IDS/IPS rules, rate limits, or firewalls that start dropping you. Scan third-party systems only with authorization (see the legality question); for your own servers, the worst realistic outcome of a web-port check is a few extra lines in the access log.

Every scan times out or fails: is the target down or is it the tool?

Both are possible. This tool can only reach HTTP(S) ports, so a host that blocks non-browser traffic, drops probes silently, or sits behind a firewall that allows only specific IPs shows all-failed even when services run. First verify that the hostname resolves and responds to a normal browser visit; then run a local check with nmap -p 80,443 target.com; open there with this tool failing means filtering on the network path, not a dead host.

The same port gave different results a few minutes apart: is that normal?

Yes, port status is a snapshot, not a constant. Services restart, firewall rules change, load balancers shift traffic, and rate limiters start dropping probes after several requests. The history panel exists for exactly this: it logs results per host so you can see the change over time. If a port flaps repeatedly, treat the latest open result as current and re-scan before relying on it.