Element Synapse

Details

The core project is provided under an AGPLv3, with an optional seemingly non-FOSS commercial license available too.

The maintainers, Element, also provide additional offerings under the same project brand, such as “Synapse Pro” which they advertise as a much more efficient version of the FOSS project:

With new functionality written in Rust, it provides a significant step change in performance and resource usage for massive Matrix deployments with high density multi-tenancy, high availability and elastic horizontal scaling. As a result, Synapse Pro’s efficiencies enable both single nation-scale servers as well as multiple small, separate instances within a single footprint […]

Based on their wording, it does not appear that this version is provided anywhere under a FOSS license:

Available under a commercial license, Synapse Pro will help fund and accelerate the continued open source development of Synapse for the benefit of all of Matrix.

On their pricing page Element provides a comparison of their offerings, where they state the “Community” FOSS offering is “actively developed by Element, but not for use in production environments”. Their comparison chart also shows green ticks for the “Open source” row for their “Enterprise” and “Sovereign” offerings which provide Synapse Pro (and Element Pro). The row label does have the sub-text of “Built on open source software to ensure users can trust the system.”, but this could still be misleading despite the questionable “Built on” cop-out.

The project is maintained by Element who appear to have raised at least $48m in funding from investors which include Protocol Labs, Metaplanet, Notion, and Dawn Capital. They appear to gain revenue from providing various wider paid related software packages, hosted services and support services.