CAT KARAT · COMPETITOR COMPARISON
Karat vs Ostinato vs Colasoft vs packETH.
GUI packet builders compared feature by feature. Karat data comes from the Karat 2.18.1 User Guide and license; data for the other tools comes from their official sites and documentation. ? = not verified, n/a = not applicable.
| Feature | Karat Packet Builder | Ostinato | Colasoft Packet Builder | packETH |
|---|---|---|---|---|
| Current version | 2.18.1 | 2.1.0 (Aug 2026) | 2.2 (Aug 2024) | 3.0 (Nov 2024 per Debian; GitHub master: GTK3) |
| License / price | Freeware, closed source; free for commercial use too | Commercial subscription: Solo $19/mo (personal use), Pro $79/mo, Business $249/mo. Open source until 2024; 1.x is "Classic" | Freeware, closed source | Open source GPL (v3 on GitHub; Fedora lists GPL-2.0+), free |
| OS | Windows 10/11 x64; Linux build available upon request | Windows, macOS; Linux on Pro/Business | Windows only | Linux only |
| Architecture | Single desktop app (Perl/Tk) | GUI controller + Drone agent(s), can run remotely | Single desktop app | Single GUI app + packETHcli |
| Built-in protocols | ~40, L2–L7: Ethernet, VLAN/QinQ, MPLS, PPPoE, LLDP, LACP, STP, OAM/CFM/Y.1731, PTP, ARP, IPv4/IPv6 + ext. headers, GRE, TCP/UDP/ICMP/ICMPv6/MLD, IGMPv1-3, OSPF, PIM, EIGRP, VRRP, DHCP/v6, DNS, NTP, RADIUS, Syslog/SNMP/NetFlow/IPFIX/sFlow | Ethernet, VLAN/QinQ, ARP, IPv4/6, ICMP, UDP, TCP (stateless), GRE, IP-in-IP and more | Templates for Ethernet, ARP, IP, TCP, UDP; other protocols through decode/hex editing | Ethernet II/802.3, 802.1q, QinQ, ARP, IPv4, IPv6, UDP, TCP, ICMP, ICMPv6, IGMP, RTP, jumbo |
| Industrial / automotive | Yes: Modbus TCP, MQTT, DNP3, IEC-104, GOOSE, SV, BACnet/IP, EtherNet/IP; SOME/IP(-SD), DoIP, CAN, gPTP, AVTP (frame builders, no live device emulation) | ? (not in the standard list; possible through user-defined protocols) | No | No |
| User-defined protocols | Yes (Custom Protocol Definition) | Yes (Pro+, via scripting) | Hex editing only | User-defined payload per layer |
| Field / hex editing | Field tabs + raw hex mode, live decode and hex highlight | Field-level + hex | Decode editor + hex + ASCII, synced | Field-level forms |
| Deliberately invalid values | Yes (length/checksum overrides) | Yes | Yes (via hex) | Yes (wrong checksum, length, etc.) |
| Field variation | MAC/IP/VLAN increment, decrement, random; size Fixed/Inc/Dec/Random/Range/IMIX | Yes (variable fields, flows; up to 1k–1M flows/port depending on tier) | Limited | Increment MAC/IP/payload bytes while sending; size and speed ramp |
| Streams | Up to 8 streams (A–H) in weighted rounds | Many streams per port, per-stream rate | Packet list sent in sequence | Single packet or sequence of packets |
| Per-stream start delay | Yes: Delay ms column per stream, 0-60000 ms after Start (default 0); measured +5..+15 ms late, never early | No dedicated setting (streams run sequentially or interleaved; order via "After this stream") | ? (per-packet delay in the sequential packet list; no per-stream start offset found) | ? (delay settings between packets/sequences; per-stream start offset not verified) |
| Rate control | Burst count, continuous, inter-packet gap; IMIX presets | pps/bps per stream; line rate with Turbo add-on (10/100/400G, paid) | Delay between packets, loop count, burst | Delay, count, max speed, ramps |
| Multi-port | One TX adapter + separate RX (capture) adapter | Yes, multi-port and multi-device (tier limits) | One adapter | One interface |
| PCAP import | Yes (open pcap, packet player, import packet N, hex dump paste) | Yes (packet count limit per tier) | Yes, many formats (pcap, pcapng, Sniffer, etc.) | Yes (pcap) |
| PCAP export | Yes (also CLI --output) | Yes | Yes | Yes |
| Capture / decode | Built-in capture tool with filters and decoder | Rx port statistics (capture via Wireshark integration) | No (Colasoft Capsa is a separate product) | Receiver/counter mode in packETHcli only |
| Statistics | TX/RX counters per adapter, 60 s rate graph, response-match report | Port statistics; stream statistics (Pro+) | Basic send count | Sent counters; drop check in CLI receiver |
| Scripting / automation | JSON scripts, macro recording, headless CLI, dry-run | Python API (Business tier) | No | packETHcli (send pcap) |
| Protocol emulation (stateful) | No (TCP Tools uses the OS stack for banner/HTTP/fuzz) | Device emulation; DHCP/OSPF/BGP/IGMP emulation (Business) | No | No |
| Testing extras | Field fuzzing, PCAP validation report, InfoSec/lab presets | RFC 2544 PerfBench (Business) | n/a | n/a |
| Performance class | Software / Npcap; moderate rates | Highest (Turbo, DPDK-class, up to 400G) | Software; low/moderate | Software, raw socket; near line rate on 1G |
Notes on fairness
- Karat is the author's own tool. Its features were read from the 2.18.1 User Guide, and they were not benchmarked. Throughput was not measured for any tool.
- Ostinato is the most capable tool for scale, multi-port testing and high-speed throughput, but it is now paid. Many features depend on the tier.
- Colasoft Packet Builder is free and simple, has strong import-format support, and runs on Windows only. Its last release was 2024.
- packETH is open source and Linux-only, and it has a small but solid protocol set.
- Competitor data checked against official sources on 31 Oct 2026.
Sources
- Karat: Karat 2.18.1 User Guide and license
- Ostinato: ostinato.org/pricing/ · ostinato.org/news/ostinato-2-0 · ostinato.org/news/
- Colasoft: www.colasoft.com/packet_builder/ · www.colasoft.com/download/products/download_packet_builder.php
- packETH: github.com/jemcek/packETH · packeth.sourceforge.net/packeth/Home.html · tracker.debian.org/pkg/packeth