The Matrix Conference 2026

A common journey to user federated search

Currently user search can only be done locally, which would at best get a list of all users known to the server.

This talk aims at explaining the research we did regarding speccing and implementing a spec change proposal for the user federated search (MSC4258).

We will also explained the different solutions we thought about and the associated tradeoffs regarding data privacy, performance and complexity.

This talk is also about a collaboration between 2 public sector teams from 2 different countries :)

Mathieu Velten

Mathieu is a long time advocate and contributor to Matrix, first as an amateur and then professionally, for Element then Tchap French deployment. He is currently working to open the French federation to third trusted parties.