Mongrel2 is an application, language, and network architecture agnostic web server that focuses on web applications using modern browser technologies.

The Transparent Inter Process Communication protocol allows applications in a clustered computer environment to communicate quickly and reliably with other applications, regardless of their location within the cluster.

Castle is a key-value store responsible for redundancy, caching, indexing and disk layout management. Acunu uses it to store all user data as well as statistics captured and displayed by the Control Center.
Castle is not cluster aware and thus it doesn’t participate in distributing data in a cluster. However, Castle interfaces are designed with distributed databases in mind, featuring timestamps and automated discarding of old, deleted data.

Softflowd is flow-based network traffic analyser capable of Cisco NetFlow data export. Softflowd semi-statefully tracks traffic flows recorded by listening on a network interface or by reading a packet capture file. These flows may be reported via NetFlow to a collecting host or summarised within softflowd itself.

io-watchdog is a facility for monitoring user applications and parallel jobs for "hangs" which typically have a side effect of ceasing all IO in a cyclic application (i.e. one that writes something to a log or data file during each cycle of computation). The io-watchdog attempts to watch all IO coming from an application and triggers a set of user-defined actions when IO has stopped for a configurable timeout period.

SLURM is an open-source resource manager designed for Linux clusters of all sizes. It provides three key functions. First it allocates exclusive and/or non-exclusive access to resources (computer nodes) to users for some duration of time so they can perform work. Second, it provides a framework for starting, executing, and monitoring work (typically a parallel job) on a set of allocated nodes. Finally, it arbitrates contention for resources by managing a queue of pending work.

CRM114 is a system to examine incoming e-mail, system log streams, data files or other data streams, and to sort, filter, or alter the incoming files or data streams according to the user's wildest desires. Criteria for categorization of data can be via a host of methods, including regexes, approximate regexes, a Hidden Markov Model, Orthogonal Sparse Bigrams, WINNOW, Correllation, KNN/Hyperspace, or Bit Entropy ( or by other means- it's all programmable).

Kamailio is able to handle thousands of call setups per second. Among features: asynchronous TCP, UDP and SCTP, secure communication via TLS for VoIP (voice, video); IPv4 and IPv6; SIMPLE instant messaging and presence with embedded XCAP server and MSRP relay; ENUM; DID and least cost routing; load balancing; routing fail-over; accounting, authentication and authorization; support for many backend systems such as MySQL, Postgres, Oracle, Radius, LDAP, Redis, Cassandra; XMLRPC control interface, SNMP monitoring. It can be used to build large VoIP servicing platforms or to scale up SIP-to-PSTN gateways, PBX systems or media servers like Asterisk™, FreeSWITCH™ or SEMS.