CAT KARAT PACKET BUILDER ·
Build the exact packet. Send it in a few clicks.
A visual packet builder for engineers, students, and test labs — with SCADA and automotive protocol builders, InfoSec presets, a field-level Packet View, multiple streams, PCAP import, and command-line automation.
Completely free · personal, educational, and commercial use · Windows · Linux build available upon request
01 / VISUAL PACKET FLOW
Compose the stack without writing code.
Select protocols, set individual fields, inspect the resulting bytes, and transmit through a chosen interface. KARAT covers Ethernet, VLAN, ARP, IPv4, IPv6, UDP, TCP, ICMP/ICMPv6, IGMPv1–3, MLDv1/v2, DHCP and DHCPv6, DNS, mDNS and LLMNR, PROFINET DCP, Ethernet OAM (802.3ah EFM) and CFM / Y.1731, and Telemetry (Syslog, SNMP v1/v2c, NetFlow v5/v9, IPFIX, sFlow v5) — while keeping raw editing available at every step.
MULTIPLE STREAMS
One interface, several independent traffic flows.
Configure separate streams, counters, packet sizes, rates, and protocol combinations. Use the visual controls for interactive work or run a fixed number of packets from the CLI and exit cleanly for automation.
- Import from PCAP or a Wireshark, tcpdump, or xxd hex dump
- Raw hex and protocol-field editing
- Packet Player with capture validation
- Reusable scripted presets and a
--run/--send NCLI - Per-flow loss, latency, and jitter; QoS and ECN profiles
INDUSTRIAL & AUTOMOTIVE
SCADA and in-vehicle traffic, built field by field.
The SCADA Protocols window builds Modbus TCP, MQTT 3.1.1, DNP3, IEC 60870-5-104, BACnet/IP, EtherNet/IP ListIdentity, IEC 61850 GOOSE, and Sampled Values. The Automotive Protocols window builds DoIP with UDS requests, SOME/IP and SOME/IP-SD, CAN / CAN-FD, gPTP, and AVTP over IPv4 or IPv6. Apply turns the result into a ready frame on the main Packet Flow.
TRAFFIC PRESETS
Start with a useful test, then change anything.
Load application mixes and laboratory profiles from thematic submenus, or pick an InfoSec preset — ready-made field sets for IDS, SIEM, and OT checks such as mDNS/LLMNR poisoning, rogue DHCPv6 advertise, DCP Set NameOfStation, or GOOSE/SV replay. Any preset can be applied from a script, and --list-infosec prints them all.
{ "infosec": "dns/mdns_query" }
FREE MEANS FREE
No trial clock. No feature paywall. No commercial-use restriction.
Cat KARAT is free for personal projects, teaching, laboratory work, and commercial testing on Windows. A Linux build is available upon request.
DOWNLOAD OPTIONS →DOWNLOAD DETAILS
System requirements and file integrity.
KARAT is a free single-edition product. Live sending and capture require packet-capture support; file-building mode does not.
Requirements
- Windows
- Windows 10/11 64-bit; Npcap for interface listing, live send, and capture
- Linux
- Linux build available upon request — undefinable@yandex.com
- Memory
- 256 MB or more recommended
- Display
- 1000×830 or larger
- Privileges
- Administrator rights may be needed for live I/O; output and dry-run modes do not need them
Packages and SHA-256
| Package | Approx. size | SHA-256 |
|---|---|---|
| Windows exe (Karat-2.18.1.exe) | — | 7cfbf4d544fac2ceddd532a52952a71ec3acf54b441c1308eaa09c784fd1edac |
| Linux build | — | Available upon request |
The complete license text supplied with the package governs use. The package includes the User Guide, release notes, scripting reference, and the SCADA and Automotive posters. Questions: undefinable@yandex.com.
SUPPORT KARAT
Help keep a professional packet builder free.
KARAT can be downloaded and used without payment. If it saves you time or helps your lab, an optional donation can support maintenance, protocol updates, testing, and documentation.
Donating is optional and does not unlock hidden features.
READY TO BUILD
From an empty frame to traffic on the wire.
Download the current release, watch the short demonstration, and start with a preset or a packet captured in your own lab.