Network & IP Tools

Free network utilities for developers and sysadmins: subnet and CIDR calculations, IP geolocation, DNS lookups, HTTP inspection, port reference, and IPv6 tools. Client-side where possible.

Subnet Calculator

Calculate subnet masks, ranges & hosts

CIDR Calculator

Network, broadcast & host range from CIDR

CIDR Overlap Calculator

Check if CIDR blocks overlap

IP Range Calculator

Calculate IP ranges & CIDR blocks

IP Lookup

Find IP geolocation, ISP & network info

DNS Lookup

Query DNS records via Cloudflare DoH

User Agent Parser

Detect browser, OS & device from UA strings

HTTP Header Viewer

Inspect HTTP response headers for any URL

Get Page Title

Fetch the HTML title & og:title from any URL

HTTP Status Lookup

Look up HTTP status codes and meanings

Port Checker

Common port reference & service lookup

IPv6 Tool

IPv6 address tools and utilities

Common Ports

Reference pages for 170 well-known TCP/UDP ports — protocols, services, and security notes for each.

Port 20 Port 21 Port 22 Port 23 Port 25 Port 43 Port 53 Port 67 Port 68 Port 69 Port 80 Port 88 Port 110 Port 111 Port 119 Port 123 Port 135 Port 137 Port 138 Port 139 Port 143 Port 161 Port 162 Port 179 Port 194 Port 389 Port 443 Port 445 Port 464 Port 465 Port 500 Port 514 Port 515 Port 520 Port 521 Port 546 Port 547 Port 554 Port 587 Port 631 Port 636 Port 853 Port 873 Port 990 Port 993 Port 995 Port 1080 Port 1194 Port 1433 Port 1434 Port 1521 Port 1701 Port 1723 Port 1812 Port 1813 Port 1883 Port 1900 Port 2049 Port 2082 Port 2083 Port 2086 Port 2087 Port 2181 Port 2222 Port 2375 Port 2376 Port 2379 Port 2380 Port 2456 Port 3000 Port 3001 Port 3005 Port 3306 Port 3389 Port 3478 Port 4000 Port 4200 Port 4243 Port 4369 Port 4443 Port 4567 Port 5000 Port 5001 Port 5060 Port 5222 Port 5228 Port 5432 Port 5500 Port 5555 Port 5601 Port 5672 Port 5900 Port 5984 Port 6379 Port 6443 Port 6660 Port 6661 Port 6662 Port 6663 Port 6664 Port 6665 Port 6666 Port 6667 Port 6697 Port 6881 Port 6882 Port 6883 Port 7000 Port 7001 Port 7070 Port 7443 Port 7474 Port 7687 Port 8000 Port 8001 Port 8008 Port 8080 Port 8081 Port 8082 Port 8083 Port 8086 Port 8088 Port 8090 Port 8123 Port 8125 Port 8126 Port 8200 Port 8300 Port 8301 Port 8302 Port 8443 Port 8444 Port 8500 Port 8554 Port 8761 Port 8800 Port 8888 Port 8983 Port 9000 Port 9001 Port 9042 Port 9043 Port 9090 Port 9091 Port 9092 Port 9093 Port 9100 Port 9200 Port 9300 Port 9418 Port 9443 Port 9500 Port 9600 Port 9870 Port 9999 Port 10000 Port 10250 Port 10255 Port 11211 Port 15672 Port 16379 Port 25565 Port 27017 Port 27018 Port 28015 Port 28017 Port 29015 Port 32400 Port 33060

HTTP Status Codes

Look up the meaning, use cases, and debugging tips for the most common HTTP response status codes.

HTTP 200 HTTP 201 HTTP 301 HTTP 302 HTTP 304 HTTP 308 HTTP 400 HTTP 401 HTTP 403 HTTP 404 HTTP 405 HTTP 408 HTTP 418 HTTP 422 HTTP 429 HTTP 500 HTTP 502 HTTP 503 HTTP 504

Discovery Pages

All Tools All Linux Commands

Related Hubs

Developer Tools HTTP Tools Security Tools

About Network & IP Tools

Network engineering and system administration require a deep understanding of how data flows across the internet. IP addressing, subnetting, and CIDR notation form the backbone of network design — determining how devices are grouped, how traffic is routed, and how address space is allocated efficiently. Whether you are planning a corporate network, configuring cloud VPCs, or debugging connectivity issues, subnet and CIDR calculators are indispensable tools that save hours of manual computation.

DNS (Domain Name System) translates human-readable hostnames into IP addresses, and understanding DNS records — A, AAAA, CNAME, MX, TXT, and SRV — is essential for domain configuration, email deliverability, and service discovery. HTTP status codes communicate the outcome of every web request: 2xx codes signal success, 3xx codes handle redirects, 4xx codes indicate client errors, and 5xx codes report server-side failures. Knowing what each code means helps developers debug APIs, configure load balancers, and implement proper error handling.

Port numbers identify specific services running on networked hosts. Well-known ports like 22 (SSH), 80 (HTTP), 443 (HTTPS), 3306 (MySQL), and 5432 (PostgreSQL) are critical knowledge for firewall configuration, container networking, and security auditing. This page provides instant reference for 170 of the most commonly used ports, along with interactive calculators and lookup tools — all running directly in your browser with no data sent to external servers.