Not checked
Run a check to see which ports are open.
Port Checker
Test whether a TCP port on a server is open by making a real connection attempt - pick from common services or enter your own port list.
Opens a real TCP connection to each port - up to 25 at a time.
A "Filtered" result usually means a firewall is silently dropping the connection.
Enter a host and choose the ports you want to check.
Ports Checked
0
real connection attempts made
Open
0
accepted the connection
Closed
0
actively refused
Filtered
0
no response at all
📊 Port Results
Sorted by port number.
Port
Service
Status
Time
📋 Query Details
Host
—
Resolved Address
—
Ports Checked
—
Checked At
—
📦 Raw API Result
"Closed" means the server itself answered and actively refused the connection - the host is reachable, nothing is just listening there. "Filtered" means nothing came back at all within the time budget, which almost always means a firewall is silently dropping the connection rather than the port genuinely being closed.
HOW IT WORKS
A Real Connection, Not a Guess
This tool resolves the host you enter, then opens an actual TCP socket to each requested port and times how long the connection attempt takes. Three distinct outcomes are reported rather than a simple open/closed: Open means the three-way handshake completed; Closed means the server responded but actively refused the connection (a TCP RST) - the host is up, nothing is just listening on that port; Filtered means no response came back at all before the timeout, which is the signature of a firewall silently dropping the connection rather than a genuinely closed port. Requests to private, loopback and other reserved address ranges are refused outright, so this cannot be used to probe internal infrastructure.
What else can you check?
These tools all work on the same connection and address data — pick whichever question you actually have.
Want to see the full path to a site?
DNS, redirects, every hop, the CDN, TLS and the origin server.
Want to know your public IP?
See your IPv4 and IPv6 addresses, location, ISP and ASN.
Want to check your tower & route?
Live ping, speed, DNS, traceroute and a map of nearby points.
Want to ping from around the world?
Real latency from real probes across 12 countries, live on a map.
Want to locate any IP address?
City, region, country and coordinates for any public IP.
Want to know if an IP is risky?
Proxy, VPN, Tor, hosting and abuse-report indicators.
Want to know if you're blacklisted?
Check an address against major spam and abuse DNSBLs.
Want to know who owns an IP?
Network owner, ASN, CIDR range and abuse contact.
Want to explore an AS number?
Announced prefixes, BGP neighbours and registry details.
Want to test your connection speed?
Measure real download, upload, ping and jitter.
Want to see what changed?
Word-level diff between two blocks of text or code.
Want to know if a DNS change is live yet?
Compare answers from five independent public resolvers.
Want to verify a domain's nameservers?
Direct authoritative checks, glue records and SOA serials.
Want to check a domain's DNSSEC setup?
DNSKEY, DS records, signature expiry and real validation.
Want to see the hop-by-hop path to a server?
A real traceroute from a genuine probe anywhere in the world.
Want to measure latency to a server?
Real connect timing - min/avg/max, jitter and connection loss.
Want a clean URL slug from a title?
Real transliteration, stop words and batch mode.
Want to find and replace across a document?
Regex, capture groups and a live preview before you commit.
Want to find the invisible character?
Code points, escapes, bytes and hidden-character detection.
Want to escape text for HTML?
Minimal, named or numeric entities, attribute-safe.
Want to strip emoji cleanly?
Whole clusters - no half-flags or stray modifiers left.
Want to spot repeated words?
Frequency, density and accidental doubles like "the the".
Port Checker FAQ
What's the difference between "Closed" and "Filtered"?
Closed means the server actively answered and refused the connection - it's reachable, that port just isn't in use. Filtered means the request got no response at all, which almost always means a firewall is dropping it silently, not that the port is genuinely unused.
Why is the port list limited to 25 at a time?
Checking many ports on an arbitrary host is functionally a small port scan. The limit, together with a tight per-minute rate limit, keeps this useful for "is my server's port open" without making it a practical tool for scanning someone else's network.
Can I check ports on a private or internal address?
No - requests to private, loopback, link-local and other reserved address ranges are refused before any connection is attempted, so this tool can't be pointed at internal infrastructure.
Why does an open port sometimes still show a service that isn't really running there?
The service name shown next to a port is just a label for the port number's conventional use (e.g. 443 = HTTPS) - it isn't detected from the connection itself. Anything can technically listen on any port.