synapse/docs/administration/admin_api/version_api.md

Version API

This API returns the running Synapse version and the Python version on which Synapse is being run. This is useful when a Synapse instance is behind a proxy that does not forward the 'Server' header (which also contains Synapse version information).

The api is:

GET /_synapse/admin/v1/server_version

It returns a JSON body like the following:

{
    "server_version": "0.99.2rc1 (b=develop, abcdef123)",
    "python_version": "3.7.8"
}