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What is Sydent?

Sydent is an identity server for the Matrix communications protocol. It allows Matrix users to prove that they own an email address or phone number, and allows _other Matrix users to look them up using that email address or phone number.

Do I need to run Sydent to run my own homeserver?

Short answer: no.

Medium answer: probably not. Most homeservers and clients use the Sydent instance run by, or use no identity server whatsoever.

Longer answer: if you want to allow user lookup via emails and phone numbers in a private federation of multiple homeservers, Sydent _might be useful for you. If you want your homeserver to be able to verify phone numbers via SMS and you have an API token for the OpenMarket HTTP SMS API, then Sydent might be useful for you.


Installing the system dependencies

To install Sydent's dependencies on a Debian-based system, run:

sudo apt-get install build-essential python3-dev libffi-dev \
                     sqlite3 libssl-dev python3-virtualenv libxslt1-dev

From here, you can either install Sydent by using a PyPI release, or by recreating Sydent's locked runtime environment.

Installing the latest Sydent release from PyPI

To create the virtual environment in which Sydent will run:

virtualenv -p python3 ~/.sydent
source ~/.sydent/bin/activate
pip install --upgrade pip
pip install --upgrade setuptools

Sydent and its dependencies can be installed using pip by running:

pip install matrix-sydent

With the virtualenv activated, you can run Sydent using:

python -m sydent.sydent

Installing from source

Alternatively, Sydent can be installed using poetry from a local git checkout. First install poetry. See poetry's documentation for details; we recommend installing via pipx. Once that's done:

git clone
cd sydent
poetry install --no-dev
# For development, pull in extra tools with
# poetry install

To start Sydent:

poetry run sydent

Running Sydent

When Sydent is first run, it will create a configuration file in sydent.conf with some defaults. If a setting is defined in both the [DEFAULT] section and another section in the configuration file, then the value in the other section is used.

You'll most likely want to change the server name ( and specify an email server (look for the settings starting with email.).

By default, Sydent will listen on This can be changed by changing the values for the configuration settings clientapi.http.bind_address and clientapi.http.port.

Sydent uses SQLite as its database backend. By default, it will create the database as sydent.db in its working directory. The name can be overridden by modifying the db.file configuration option. Sydent is known to be working with SQLite version 3.16.2 and later.

Listening for HTTPS connections

Most homeservers and clients will expect identity servers to be reachable using HTTPS.

Sydent does not currently support listening for HTTPS connection by itself. Instead, it is recommended to use a reverse proxy to proxy requests from homeservers and clients to Sydent. It is then possible to have this reverse proxy serve Sydent's API over HTTPS.

When using a reverse proxy, it is recommended to limit the requests proxied to Sydent to ones which paths start with /_matrix/identity for security reasons.

An exception to this is Sydent's internal replication API, see docs/

SMS originators

Defaults for SMS originators will not be added to the generated config file, these should be added to the [sms] section of that config file in the form:

originators.<country code> = <long|short|alpha>:<originator>

Where country code is the numeric country code, or default to specify the originator used for countries not listed. For example, to use a selection of long codes for the US/Canada, a short code for the UK and an alphanumertic originator for everywhere else:

originators.1 = long:12125552368,long:12125552369
originators.44 = short:12345
originators.default = alpha:Matrix


A Dockerfile is provided for sydent. To use it, run docker build -t sydent . in a sydent checkout. To run it, use docker run --env=SYDENT_SERVER_NAME=my-sydent-server -p 8090:8090 sydent.

Persistent data

By default, all data is stored in /data. To persist this to disk, bind /data to a Docker volume.

docker volume create sydent-data
docker run ... --mount type=volume,source=sydent-data,destination=/data sydent

But you can also bind a local directory to the container. However, you then have to pay attention to the file permissions.

mkdir /path/to/sydent-data
chown 993:993 /path/to/sydent-data
docker run ... --mount type=bind,source=/path/to/sydent-data,destination=/data sydent

Environment variables


These variables are only taken into account at first start and are written to the configuration file.

Variable Name Sydent default Dockerfile default
SYDENT_CONF sydent.conf /data/sydent.conf
SYDENT_DB_PATH sydent.db /data/sydent.db

Internal bind and unbind API

It is possible to enable an internal API which allows for binding and unbinding between identifiers and matrix IDs without any validation. This is open to abuse, so is disabled by default, and when it is enabled, is available only on a separate socket which is bound to localhost by default.

To enable it, configure the port in the config file. For example:

internalapi.http.port = 8091

To change the address to which that API is bound, set the internalapi.http.bind_address configuration setting in the [http] section, for example:

internalapi.http.port = 8091
internalapi.http.bind_address =

As already mentioned above, this is open to abuse, so make sure this address is not publicly accessible.

To use bind:

curl -XPOST 'http://localhost:8091/_matrix/identity/internal/bind' -H "Content-Type: application/json" -d '{"address": "", "medium": "email", "mxid": ""}'

The response has the same format as /_matrix/identity/api/v1/3pid/bind.

To use unbind:

curl -XPOST 'http://localhost:8091/_matrix/identity/internal/unbind' -H "Content-Type: application/json" -d '{"address": "", "medium": "email", "mxid": ""}'

The response has the same format as /_matrix/identity/api/v1/3pid/unbind.


It is possible to configure a mesh of Sydent instances which replicate identity bindings between each other. See docs/


Matrix room: