10 Best Online Port Scanners for 2026

Need to confirm whether a port is reachable from the internet? A browser-based port scanner can test your public IP without an installation. The right choice depends on whether you need to check one forwarded port, scan a server’s common ports or inventory exposures across multiple assets.

Quick picks: YouGetSignal for one port and home router troubleshooting; IPVoid for a straightforward external TCP check; HackerTarget for a quick Nmap-based check of ten common TCP ports; Pentest-Tools.com for more advanced TCP and UDP assessment.

How this list was selected: We reviewed current product pages for a browser-accessible scan or exposure lookup, the type of result, limits stated by the provider and the task each tool handles best. This is a feature-based editorial comparison, not a hands-on speed or detection benchmark. Tool interfaces, quotas and prices may change; confirm them on the linked product pages before buying.

Online port scanners compared

Important distinction: The first eight entries send probes or connection requests for a check. Censys and Shodan let you search data gathered by their own ongoing scans. An indexed record may be older than your latest firewall change.

1. YouGetSignal: best for checking one forwarded port

YouGetSignal’s Open Port Check Tool lets you test whether a port on an external IP is reachable. It is a quick fit when a game server, remote service or newly configured port-forwarding rule is failing. Enter your public IP and port, run the check, then compare the result with your router and host firewall settings.

Strength: Minimal setup and a clear answer for a specific port. Limit: It is not a full server inventory or service-version assessment. An ISP can also block particular ports upstream.

2. IPVoid: best simple browser-based TCP scanner

IPVoid’s TCP Port Scanner accepts IPv4 or IPv6 addresses and offers common-port and custom-port choices. Its page says the scan uses Nmap. This makes it useful for checking the externally reachable TCP ports on an IP you control after a deployment or firewall edit.

Strength: A more useful port selection than a single-port checker. Limit: The service specifies that you may scan only authorized IPs and limits the same IP to five scans per day. Its separate UDP tool is a different page.

3. HackerTarget: best quick Nmap scan of common services

HackerTarget’s Nmap Online Port Scanner offers a free quick scan of ten common TCP ports, including 22, 80, 443, 445 and 3389, with Nmap service-version detection enabled. That is more actionable than a yes/no port check when you want an initial look at common externally exposed services.

Strength: A defined free scan scope and service detection. Limit: A clean result does not establish that other TCP ports are closed. Membership adds broader port and subnet scans, scheduling and exports.

4. Pentest-Tools.com: best for deeper online TCP and UDP scanning

Pentest-Tools.com’s Port Scanner with Nmap supports TCP and UDP selections, common or specified ports, service-version detection and deeper scanning options. It is suited to an authorized assessment where the team needs a report and follow-up checks rather than a single connectivity answer.

Strength: Broad configuration without installing Nmap locally. Limit: The provider advertises a seven-day full-scanner trial requiring a business email and card, so do not describe all capabilities as permanently free. Large UDP scans can take longer and may yield uncertain states.

5. DNSChecker: best for a quick custom-port check

DNSChecker’s Port Checker provides a browser interface for checking specified ports; its own guidance gives 80 and 443 as a custom-port example. It is convenient when you already know which service should be reachable.

Strength: Fast, accessible custom checks. Limit: Its page advertises TCP and UDP results with sweeping accuracy claims. Do not interpret a silent UDP response as proof a port is closed: UDP often cannot produce a definitive answer without a protocol-aware response.

6. WhatsMyIP.org: best for server and game-port presets

WhatsMyIP.org’s Port Scanners groups checks into common server, game, application and P2P ports, plus a single custom port. It is useful when you know the application category but do not remember its usual port number.

Strength: Practical presets and little setup. Limit: A preset is not a comprehensive scan, and applications can listen on nonstandard ports. The provider notes that its server attempts to connect to the host being checked.

7. GRC ShieldsUP!: best for checking your own internet connection

GRC ShieldsUP! probes the connection from which you access the site. It is useful when you want an outside view of a home or small-office network and need to understand what your router and firewall expose.

Strength: A connection-focused check with clear permission language. Limit: It tests the internet-facing path to your current connection; it will not inventory other cloud servers, private LAN devices or every IPv6 configuration automatically.

8. WhatIsMyIP.com: best for a beginner-friendly port scanner

WhatIsMyIP.com’s Port Scanner is useful for an occasional public-IP connectivity check. Select a port or available preset and confirm whether the service can be reached from outside your network.

Strength: Accessible for non-specialists. Limit: Scan modes and allowances can depend on the current account plan. Check its live tool and pricing before relying on a specific range or custom-port feature.

9. Censys: best for searching previously observed exposure

Censys Platform is an internet intelligence search product. Search your public IPs or known assets to see services recorded in its dataset, then verify important findings with a fresh authorized scan. It is especially useful when you are trying to spot a public service that was missed by your internal inventory.

Strength: Discovering exposure across internet-facing assets. Limit: Search results are not a live reachability test, and access conditions can change. In 2026, Censys says its legacy Search is disabled for free users and directs them to the new platform.

10. Shodan: best for researching internet-facing services

Shodan indexes observations of internet-connected devices and services. Search an IP or asset you manage to examine banners and other recorded evidence, then check live connectivity before changing a firewall rule or reporting an exposure.

Strength: Context and historical observations beyond a one-port test. Limit: It is a search engine for collected scan data, not a button to run your own immediate full scan. Account features and freshness differ by query and plan.

How to choose an online port scanner

1. Need to test one port? Start with YouGetSignal or WhatsMyIP.org.
2. Need to see common TCP exposure on one owned server? Use IPVoid or HackerTarget.
3. Need UDP, configurable scope or a report? Assess Pentest-Tools.com’s current plan and trial.
4. Need to find public assets you might have overlooked? Search Censys or Shodan and verify each finding live.
5. Need private-network coverage? Use a local scanner such as Nmap from an authorized network vantage point. A public website cannot directly scan private RFC 1918 addresses behind your router.

Reading results without false confidence

• Open: The scanner received evidence that a service is reachable on that port from its location. Check whether that service is expected, patched, authenticated and appropriately restricted.
• Closed: The host was reachable but the specific TCP port did not accept the connection at scan time. A service might still be reachable through another IP, protocol or route.
• Filtered or timed out: A firewall, packet loss or another network control prevented a clear answer. It does not automatically prove the host is safe.
• UDP open|filtered: With some UDP probes, silence cannot distinguish an open port from one whose packets were filtered. Confirm with a protocol-specific query where possible. Nmap’s official port-state guide explains the states.

A port scan identifies exposure; it does not prove a vulnerability. Port 443 should normally be reachable on a public website. The question is whether the software and access on that port are configured safely.

A reliable five-step check

1. Get written authorization and identify the exact public IP or hostname in scope.
2. Confirm its current DNS resolution and whether a CDN or load balancer sits in front of the origin.
3. Run a small live scan from outside the network; record the date, scanner and ports tested.
4. Investigate unexpected open ports on the server and firewall. Verify an indexed finding with a live test.
5. Fix the exposure, then rescan from the same external vantage point and document the change.

Example: You changed a firewall rule to block public access to an admin service on TCP 3389. First check the intended public IP and port with an external scanner. If it still appears open, check the cloud security group, router forwarding rule and host firewall. If it appears closed, confirm the service remains reachable through its approved private access route. Do not infer from a single result that all hosts or all ports are protected.

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