Crossbar.io is a start up from Erlangen, Germany with a focus on commercial open source software.

We initiated the development of the open Web Application Messaging Protocol (WAMP), and continue to be a central driver in its development.

We drive the development of Crossbar.io, an open source WAMP router, and the Autobahn WAMP client libraries, which are central parts of the WAMP ecosystem.

Crossbar.io is offering commercial support and services for the Crossbar.io router and Autobahn libraries, both during development (Development Acceleration Pacakge) and in production (Enterprise Support).

We are working on an online service which enables remote monitoring and management of Crossbar.io instances, as well as adding high-availability and clustering for professional deployments. Public alpha test access to this is available.

wide-angle photo of the Crossbar.io office in Erlangen
Our office in Erlangen


For a project of a former company (Tavendo) of Tobias Oberstein (co-founder), a bi-directional connection into the browser was needed. At this time, WebSocket was being defined, and Tobias Oberstein participated in the IETF working group for this.

With WebSocket as the transport, Tobias Oberstein created the first version of the WAMP protocol (back then still WebSocket Application Messaging Protocol), which was registered as only the fourth WebSocket subprotocol.

WAMP was open from the beginning, and the collective experience of implementers (both from Tavendo and third-party) was used to launch version 2. This now contained routed Remote Procedure Calls as well as PubSub.

With the expansion of the WAMP ecosystem and rising interest in Crossbar.io and the Autobahn libraries, at the end of 2016 Crossbar.io GmbH was founded. This now focusses solely on pushing the WAMP ecosystem forward and to providing commercial support and services for Crossbar.io and the Autobahn libraries.


We value openness. Open Source software is a proven development model for a wide range of software - including our field of messaging middleware. Today's software could not be developed anymore without open source. We are proud to contribute code under open source licenses to be used by anybody out there.

We value security. Soon everything is going to contain a computer. Careful design, permanent vigilance and fast reactions are necessary to keep this system of the world that we are building functioning.

We value privacy. In many societies we are nearing the point where a complete picture of everybody's actions is automatically generated and stored. Surveillance often is a matter not of collection of data, but of access to data that has already been collected. Data generation and data generation should be minimized, and safe data storage is a priority if we want to preserve the privacy necessary for a free society.

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