25 Free Online Networking Tools
FileCrankβs Networking Tools give network engineers, sysadmins, developers, and students a complete set of 25 browser-based utilities β no terminal, no install, no signup required. Calculate subnets and CIDR ranges, perform DNS lookups, detect your public IP, look up port numbers and HTTP status codes, and convert between network speed units in seconds. Every calculation runs client-side, so your data never leaves your device.
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All Networking Tools (25)
My IP Address
Detect and display your public IP address, version, type, and class
IPv4 to IPv6 Converter
Convert an IPv4 address to its IPv6-mapped and 6to4 representations
IPv6 to IPv4 Converter
Extract the embedded IPv4 address from an IPv6-mapped or 6to4 address
CIDR Range Expander
Expand a CIDR notation into the full list of IP addresses in the range
IP Class Detector
Determine the classful network class (A/B/C/D/E) of an IPv4 address
Private IP Checker
Check whether an IPv4 or IPv6 address is in a private or reserved range
IP Geolocation Lookup
Display approximate geographic location, ISP, and AS info for any IP address
IPv4 Subnet Calculator
Calculate network address, broadcast, first/last usable host, subnet mask, wildcard mask, and host count from CIDR
IPv6 Subnet Calculator
Calculate network prefix, first/last address, and address count from an IPv6 CIDR
Subnet to CIDR Converter
Convert a subnet mask (e.g. 255.255.255.0) to CIDR notation (e.g. /24)
Wildcard Mask Calculator
Calculate the wildcard mask from a subnet mask and vice versa
Supernet Calculator
Find the smallest supernet (summary route) that covers multiple input subnets
VLSM Calculator
Allocate variable-length subnets from a parent CIDR given a list of required host counts
DNS Lookup
Query A, AAAA, MX, TXT, NS, CNAME, SOA records for any domain via DNS-over-HTTPS
Reverse DNS Lookup
Perform a PTR lookup for an IP address via DNS-over-HTTPS
DNS Propagation Checker
Check DNS resolution across multiple global resolvers to verify propagation status
TTL Calculator
Convert a TTL value (seconds) to human-readable duration and calculate cache expiry
WHOIS Domain Lookup
Look up registration, registrar, creation date, expiry, name servers, and DNSSEC status for any domain using RDAP.
Bandwidth Calculator
Calculate file transfer time given file size and bandwidth
Latency Calculator
Calculate round-trip time, one-way latency, and bandwidth-delay product
Network Speed Converter
Convert between bps, Kbps, Mbps, Gbps, MBps, GBps (SI and binary)
Packet Loss Impact Calculator
Estimate throughput degradation given packet loss rate and TCP RTT
Port Number Lookup
Search well-known and registered port numbers with protocol and service name
HTTP Status Code Reference
Searchable reference of all HTTP status codes with descriptions and use cases
MAC Address Lookup
Validate a MAC address and look up the vendor from the bundled OUI database
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Got Questions?
Frequently Asked Questions
- Are all networking tools completely free?
- Yes. All 25 networking tools on FileCrank are free to use with no subscription, no API key, and no hidden fees. Client-side tools process everything in your browser; the small number of tools that perform live lookups (DNS, IP geolocation, public IP detection) use outbound API calls but remain free.
- Do the networking tools run in the browser without sending my data to a server?
- Most tools β including the subnet calculator, CIDR range expander, bandwidth calculator, and all reference lookups β run entirely client-side. Your IP addresses, CIDR blocks, and network data never leave your device. The DNS lookup, reverse DNS, and IP geolocation tools make outbound requests to third-party APIs to perform live queries, which is inherent to their function.
- What is a subnet calculator and when do I need one?
- A subnet calculator takes a CIDR block (e.g., 192.168.1.0/24) and computes the network address, broadcast address, first and last usable host IPs, subnet mask, wildcard mask, and total host count. You need it when planning IP address allocation, configuring routers and firewalls, or studying for CCNA and other networking certifications.
- What is CIDR notation?
- CIDR (Classless Inter-Domain Routing) notation represents an IP address and its associated routing prefix as a single string β for example, 10.0.0.0/22. The number after the slash indicates how many bits are used for the network portion. FileCrankβs CIDR Range Expander lists every individual IP address within any CIDR block.
- Can I look up what service uses a specific port number?
- Yes. The Port Number Lookup tool contains the full IANA registry of well-known (0β1023) and registered (1024β49151) port numbers with their associated protocol (TCP/UDP) and service name. Search by port number or service name.
- How do I find my public IP address?
- Use the My IP Address tool. It detects and displays your current public IPv4 and IPv6 addresses, IP version, and for IPv4, the address class. No input needed β the result appears on page load.
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