Local-first
Network engineering tools that never send your data anywhere
Paste a network diagram, an address plan or a device configuration. Every calculation happens in this tab — nothing is uploaded, nothing is logged, and everything keeps working with no network at all.
- 22
- tools
- 5
- categories
- 0
- network calls
Browse the toolsor press⌘K
- No accounts, no telemetry
- Installs as an app, works offline
- Every tool declares whether it uses the network
IP Addressing & Routing
Subnetting, VLSM planning, route summarization, IPv6 and address arithmetic.
- IPv4 Subnet CalculatorNetwork and broadcast address, usable host range, netmask and wildcard mask, host counts and the special-purpose classification for any address and prefix.
- VLSM Subnet PlannerSplit one block into right-sized VLANs: best-fit allocation for every host count, growth headroom, /31 point-to-point links, plus the leftover free blocks and a utilization figure.
- Route Summarization CalculatorReduce a list of prefixes to the minimal exact cover, the single covering supernet, and the holes that the supernet would advertise but nobody owns.
- BGP Aggregation & Suppress-Map BuilderBuild a BGP aggregate plan for Cisco, Huawei, Arista or Juniper: what summary-only suppresses, what must stay visible, and which routes fall outside the aggregate and would be blackholed.
- IPv6 Subnet CalculatorNetwork address, last address, total and usable address counts for any IPv6 prefix, with /127 point-to-point and /128 host-route handling, reverse-DNS zone and classification.
- IPv6 Address Compressor & ExpanderNormalize IPv6 addresses to the RFC 5952 canonical text form, expand them to eight full groups, and see the binary and hex-group forms side by side. One address per line.
- IPv6 Prefix SplitterSplit an IPv6 prefix into equal sub-prefixes: the subnet count, the first and last blocks, and a CSV export of the full list. The output is capped so large splits never freeze the tab.
- IPv6 EUI-64 ConverterDerive the EUI-64 interface identifier and link-local address from a MAC address, or work backwards from an interface identifier to the MAC, with the universal/local bit flip explained.
- IP Address Format ConverterRead an IPv4 address in any notation — dotted decimal, hex, dotted hex, decimal integer, octal or binary — and see all six representations plus the radix that was detected.
Protocols & Standards
DHCP options, vendor TLVs, MAC and OUI handling, ASN formats, BGP regex.
- MAC Address Format ConverterPaste a MAC in any notation and get every convention back at once — Cisco, Linux, Windows, bare hex — plus the multicast and locally-administered bits and the EUI-64 / IPv6 link-local form.
- MAC OUI Vendor LookupPaste a MAC or a bare OUI and get the registered vendor, the assignment type (MA-L, MA-M or MA-S) and whether the address is globally unique or locally administered. Curated offline subset of the IEEE registry.
- ASN Format ConverterConvert an Autonomous System Number between asplain (4200000000) and asdot (64086.59904) in both directions, and see whether it is 16-bit or 32-bit, private, reserved or AS_TRANS.
- BGP AS-Path Regex TesterTest a BGP AS-path regular expression against a list of real AS paths, one answer per line. Expands the Cisco underscore metacharacter, explains each token in plain language and ships a preset library.
- DHCP Option 43 GeneratorBuild the DHCP option 43 value that points access points at their wireless controller, with the per-sub-option breakdown, the Cisco dotted hex, a per-vendor CLI, and a generic TLV builder for anything not covered.
Cheatsheets
Ports, protocol numbers, header overhead and cross-vendor CLI equivalents.
- TCP/UDP Port LookupSearch TCP, UDP and SCTP port assignments by number, service name or purpose, with the IANA or vendor source and a confidence marker on every row.
- IP Protocol NumbersEvery assigned IANA IP protocol number with its registry keyword and RFC — ICMP 1, TCP 6, UDP 17, GRE 47, ESP 50, OSPF 89, VRRP 112 — plus a bulk mode that names a pasted list of numbers.
- Protocol Header Overhead & MTUHeader sizes for every common encapsulation, plus a stack builder that turns Ethernet, VLAN, PPPoE, MPLS, GRE, IPsec, VXLAN, Geneve and SRv6 into a total, an effective MTU and the TCP MSS for IPv4 and IPv6.
- Vendor CLI Cross-ReferenceTwenty operational tasks — BGP summary, MAC table, LLDP, port mirroring, packet capture, save and diff — with the command for IOS, IOS-XE, IOS-XR, NX-OS, EOS, VRP, Comware and Junos side by side.
Datacenter & Cabling
PDU power and current, cooling load, cabling pinouts and optics compatibility.
- PDU Power & Breaker CalculatorTurn a rack load in watts into line current for single- or three-phase feeds, apply the 80 % continuous derating, pick the next standard breaker size and count the C13 and C19 receptacles the load needs.
- BTU & Cooling Load CalculatorA live converter between watts, kilowatts, BTU/hr, tons of refrigeration and kcal/h, plus CRAC sizing: enter the rack load, see the heat rejection and the recommended unit size with a stated redundancy factor.
- Cabling Pinout & Fiber Polarity ReferenceT568A and T568B side by side as tables and as color-coded strip diagrams, plus crossover and Cisco rollover wiring, PoE Mode A/B pin usage with the 802.3af/at/bt classes, MPO/MTP polarity A/B/C and the copper and fiber Ethernet standards.
Credentials & Keys
Device password formats, hashes, certificates and SSH keys — all local.