free netflow analyzer
pmacct is a small set of multi-purpose passive network monitoring tool
Enterprise Network Flow Collector (IPFIX, sFlow, Netflow)
FlowViewer is a web-based netflow data analysis tool.
ipt-netflow binaries for openwrt
NetFlow iptables module for Linux kernel
TCP and UDP network buffer
Buffers, forwards, and splits flow data including NetFlow and IPFIX
Various TCP/IP servers, clients and network management tools
netflow collecting and processing tools