diff --git a/.gitignore b/.gitignore
index e46fba2..2d29d1c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,3 @@
+config.yaml
 discord
+registration.yaml
diff --git a/config/appservice.go b/config/appservice.go
index 24f62eb..f6768b1 100644
--- a/config/appservice.go
+++ b/config/appservice.go
@@ -5,6 +5,10 @@ type appservice struct {
 	Hostname string `yaml:"hostname"`
 	Port     uint16 `yaml:"port"`
 
+	ID string `yaml:"id"`
+
+	Bot bot `yaml:"bot"`
+
 	ASToken string `yaml:"as_token"`
 	HSToken string `yaml:"hs_token"`
 }
diff --git a/config/bot.go b/config/bot.go
new file mode 100644
index 0000000..4318823
--- /dev/null
+++ b/config/bot.go
@@ -0,0 +1,7 @@
+package config
+
+type bot struct {
+	Username    string `yaml:"username"`
+	Displayname string `yaml:"displayname"`
+	Avatar      string `yaml:"avatar"`
+}
diff --git a/config/bridge.go b/config/bridge.go
new file mode 100644
index 0000000..4ff6324
--- /dev/null
+++ b/config/bridge.go
@@ -0,0 +1,40 @@
+package config
+
+import (
+	"bytes"
+	"text/template"
+)
+
+type bridge struct {
+	UsernameTemplate string `yaml:"username_template"`
+
+	usernameTemplate *template.Template `yaml:"-"`
+}
+
+func (b *bridge) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	type rawBridge bridge
+
+	raw := rawBridge{}
+
+	err := unmarshal(&raw)
+	if err != nil {
+		return err
+	}
+
+	raw.usernameTemplate, err = template.New("username").Parse(raw.UsernameTemplate)
+	if err != nil {
+		return err
+	}
+
+	*b = bridge(raw)
+
+	return nil
+}
+
+func (b bridge) FormatUsername(userid string) string {
+	var buffer bytes.Buffer
+
+	b.usernameTemplate.Execute(&buffer, userid)
+
+	return buffer.String()
+}
diff --git a/config/config.go b/config/config.go
index d0093c7..fe89d2b 100644
--- a/config/config.go
+++ b/config/config.go
@@ -9,6 +9,7 @@ import (
 type Config struct {
 	Homeserver homeserver `yaml:"homeserver"`
 	Appservice appservice `yaml:"appservice"`
+	Bridge     bridge     `yaml:"bridge"`
 }
 
 func FromBytes(data []byte) (*Config, error) {
@@ -33,3 +34,12 @@ func FromFile(filename string) (*Config, error) {
 
 	return FromBytes(data)
 }
+
+func (cfg *Config) Save(filename string) error {
+	data, err := yaml.Marshal(cfg)
+	if err != nil {
+		return err
+	}
+
+	return ioutil.WriteFile(filename, data, 0600)
+}
diff --git a/config/registration.go b/config/registration.go
new file mode 100644
index 0000000..dfed824
--- /dev/null
+++ b/config/registration.go
@@ -0,0 +1,33 @@
+package config
+
+import (
+	"fmt"
+	"regexp"
+
+	as "maunium.net/go/mautrix/appservice"
+)
+
+func (cfg *Config) CopyToRegistration(registration *as.Registration) error {
+	registration.ID = cfg.Appservice.ID
+	registration.URL = cfg.Appservice.Address
+
+	falseVal := false
+	registration.RateLimited = &falseVal
+
+	registration.SenderLocalpart = cfg.Appservice.Bot.Username
+
+	pattern := fmt.Sprintf(
+		"^@%s:%s$",
+		cfg.Bridge.FormatUsername("[0-9]+"),
+		cfg.Homeserver.Domain,
+	)
+
+	userIDRegex, err := regexp.Compile(pattern)
+	if err != nil {
+		return err
+	}
+
+	registration.Namespaces.RegisterUserIDs(userIDRegex, true)
+
+	return nil
+}
diff --git a/go.mod b/go.mod
index c323554..9f440d6 100644
--- a/go.mod
+++ b/go.mod
@@ -5,6 +5,15 @@ go 1.17
 require (
 	github.com/alecthomas/kong v0.2.18
 	gopkg.in/yaml.v2 v2.4.0
+	maunium.net/go/mautrix v0.9.27
 )
 
-require github.com/pkg/errors v0.9.1 // indirect
+require (
+	github.com/btcsuite/btcutil v1.0.2 // indirect
+	github.com/gorilla/mux v1.8.0 // indirect
+	github.com/gorilla/websocket v1.4.2 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	golang.org/x/crypto v0.0.0-20210220033148-5ea612d1eb83 // indirect
+	golang.org/x/net v0.0.0-20210220033124-5f55cee0dc0d // indirect
+	maunium.net/go/maulogger/v2 v2.2.4 // indirect
+)
diff --git a/go.sum b/go.sum
index 89b39b0..d01b493 100644
--- a/go.sum
+++ b/go.sum
@@ -1,19 +1,80 @@
+github.com/aead/siphash v1.0.1/go.mod h1:Nywa3cDsYNNK3gaciGTWPwHt0wlpNV15vwmswBAUSII=
 github.com/alecthomas/kong v0.2.18 h1:H05f55eRO5f9gusObxgjpqKtozJNvniqMTuOPnf+2SQ=
 github.com/alecthomas/kong v0.2.18/go.mod h1:ka3VZ8GZNPXv9Ov+j4YNLkI8mTuhXyr/0ktSlqIydQQ=
+github.com/btcsuite/btcd v0.20.1-beta/go.mod h1:wVuoA8VJLEcwgqHBwHmzLRazpKxTv13Px/pDuV7OomQ=
+github.com/btcsuite/btclog v0.0.0-20170628155309-84c8d2346e9f/go.mod h1:TdznJufoqS23FtqVCzL0ZqgP5MqXbb4fg/WgDys70nA=
+github.com/btcsuite/btcutil v0.0.0-20190425235716-9e5f4b9a998d/go.mod h1:+5NJ2+qvTyV9exUAL/rxXi3DcLg2Ts+ymUAY5y4NvMg=
+github.com/btcsuite/btcutil v1.0.2 h1:9iZ1Terx9fMIOtq1VrwdqfsATL9MC2l8ZrUY6YZ2uts=
+github.com/btcsuite/btcutil v1.0.2/go.mod h1:j9HUFwoQRsZL3V4n+qG+CUnEGHOarIxfC3Le2Yhbcts=
+github.com/btcsuite/go-socks v0.0.0-20170105172521-4720035b7bfd/go.mod h1:HHNXQzUsZCxOoE+CPiyCTO6x34Zs86zZUiwtpXoGdtg=
+github.com/btcsuite/goleveldb v0.0.0-20160330041536-7834afc9e8cd/go.mod h1:F+uVaaLLH7j4eDXPRvw78tMflu7Ie2bzYOH4Y8rRKBY=
+github.com/btcsuite/snappy-go v0.0.0-20151229074030-0bdef8d06723/go.mod h1:8woku9dyThutzjeg+3xrA5iCpBRH8XEEg3lh6TiUghc=
+github.com/btcsuite/websocket v0.0.0-20150119174127-31079b680792/go.mod h1:ghJtEyQwv5/p4Mg4C0fgbePVuGr935/5ddU9Z3TmDRY=
+github.com/btcsuite/winsvc v1.0.0/go.mod h1:jsenWakMcC0zFBFurPLEAyrnc/teJEM1O46fmI40EZs=
+github.com/davecgh/go-spew v0.0.0-20171005155431-ecdeabc65495/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
+github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
+github.com/gorilla/mux v1.8.0 h1:i40aqfkR1h2SlN9hojwV5ZA91wcXFOvkdNIeFDP5koI=
+github.com/gorilla/mux v1.8.0/go.mod h1:DVbg23sWSpFRCP0SfiEN6jmj59UnW/n46BH5rLB71So=
+github.com/gorilla/websocket v1.4.2 h1:+/TMaTYc4QFitKJxsQ7Yye35DkWvkdLcvGKqM+x0Ufc=
+github.com/gorilla/websocket v1.4.2/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
+github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
+github.com/jessevdk/go-flags v0.0.0-20141203071132-1679536dcc89/go.mod h1:4FA24M0QyGHXBuZZK/XkWh8h0e1EYbRYJSGM75WSRxI=
+github.com/jrick/logrotate v1.0.0/go.mod h1:LNinyqDIJnpAur+b8yyulnQw/wDuN1+BYKlTRt3OuAQ=
+github.com/kkdai/bstream v0.0.0-20161212061736-f391b8402d23/go.mod h1:J+Gs4SYgM6CZQHDETBtE9HaSEkGmuNXF86RwHhHUvq4=
+github.com/lib/pq v1.9.0/go.mod h1:AlVN5x4E4T544tWzH6hKfbfQvm3HdbOxrmggDNAPY9o=
+github.com/mattn/go-sqlite3 v1.14.6/go.mod h1:NyWgC/yNuGj7Q9rpYnZvas74GogHl5/Z4A/KQRfk6bU=
+github.com/onsi/ginkgo v1.6.0/go.mod h1:lLunBs/Ym6LB5Z9jYTR76FiuTmxDTDusOGeTQH+WWjE=
+github.com/onsi/ginkgo v1.7.0/go.mod h1:lLunBs/Ym6LB5Z9jYTR76FiuTmxDTDusOGeTQH+WWjE=
+github.com/onsi/gomega v1.4.3/go.mod h1:ex+gbHU/CVuBBDIJjb2X0qEXbFg53c61hWP/1CpauHY=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/tidwall/gjson v1.6.8/go.mod h1:zeFuBCIqD4sN/gmqBzZ4j7Jd6UcA2Fc56x7QFsv+8fI=
+github.com/tidwall/match v1.0.3/go.mod h1:eRSPERbgtNPcGhD8UCthc6PmLEQXEWd3PRB5JTxsfmM=
+github.com/tidwall/pretty v1.0.2/go.mod h1:XNkn88O1ChpSDQmQeStsy+sBenx6DDtFZJxhVysOjyk=
+github.com/tidwall/sjson v1.1.5/go.mod h1:VuJzsZnTowhSxWdOgsAnb886i4AjEyTkk7tNtsL7EYE=
+golang.org/x/crypto v0.0.0-20170930174604-9419663f5a44/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
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 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/fsnotify.v1 v1.4.7/go.mod h1:Tz8NjZHkW78fSQdbUxIjBTcgA1z1m8ZHf0WmKUhAMys=
+gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7/go.mod h1:dt/ZhP58zS4L8KSrWDmTeBkI65Dw0HsyUHuEVlX15mw=
+gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
 gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b h1:h8qDotaEPuJATrMmW04NCwg7v22aHH28wwpauUhK9Oo=
 gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+maunium.net/go/maulogger/v2 v2.2.4 h1:oV2GDeM4fx1uRysdpDC0FcrPg+thFicSd9XzPcYMbVY=
+maunium.net/go/maulogger/v2 v2.2.4/go.mod h1:TYWy7wKwz/tIXTpsx8G3mZseIRiC5DoMxSZazOHy68A=
+maunium.net/go/mautrix v0.9.27 h1:6MV6YSCGqfw8Rb0G1PHjTOkYkTY0vcZaz6wd+U+V1Is=
+maunium.net/go/mautrix v0.9.27/go.mod h1:7IzKfWvpQtN+W2Lzxc0rLvIxFM3ryKX6Ys3S/ZoWbg8=
diff --git a/main.go b/main.go
index 8ac2f05..844088a 100644
--- a/main.go
+++ b/main.go
@@ -8,13 +8,15 @@ import (
 
 	"gitlab.com/beeper/discord/consts"
 	"gitlab.com/beeper/discord/globals"
+	"gitlab.com/beeper/discord/registration"
 	"gitlab.com/beeper/discord/version"
 )
 
 var cli struct {
 	globals.Globals
 
-	Version version.Cmd `kong:"cmd,help='Display the version and exit'"`
+	GenerateRegistration registration.Cmd `kong:"cmd,help='Generate the registration file for synapse and exit'"`
+	Version              version.Cmd      `kong:"cmd,help='Display the version and exit'"`
 }
 
 func main() {
diff --git a/registration/cmd.go b/registration/cmd.go
new file mode 100644
index 0000000..667506f
--- /dev/null
+++ b/registration/cmd.go
@@ -0,0 +1,59 @@
+package registration
+
+import (
+	"fmt"
+	"regexp"
+
+	"maunium.net/go/mautrix/appservice"
+
+	"gitlab.com/beeper/discord/config"
+	"gitlab.com/beeper/discord/globals"
+)
+
+type Cmd struct {
+	Filename string `kong:"flag,help='The filename to store the registration into',name='REGISTRATION',short='r',default='registration.yaml'"`
+}
+
+func (c *Cmd) Run(g *globals.Globals) error {
+	cfg, err := config.FromFile(g.Config)
+	if err != nil {
+		return err
+	}
+
+	registration := appservice.CreateRegistration()
+
+	// Load existing values from the config into the registration.
+	if err := cfg.CopyToRegistration(registration); err != nil {
+		return err
+	}
+
+	// Save the new App and Server tokens in the config.
+	cfg.Appservice.ASToken = registration.AppToken
+	cfg.Appservice.HSToken = registration.ServerToken
+
+	// Workaround for https://github.com/matrix-org/synapse/pull/5758
+	registration.SenderLocalpart = appservice.RandomString(32)
+
+	// Register the bot's user.
+	pattern := fmt.Sprintf(
+		"^@%s:%s$",
+		cfg.Appservice.Bot.Username,
+		cfg.Homeserver.Domain,
+	)
+	botRegex, err := regexp.Compile(pattern)
+	if err != nil {
+		return err
+	}
+	registration.Namespaces.RegisterUserIDs(botRegex, true)
+
+	// Finally save the registration and the updated config file.
+	if err := registration.Save(c.Filename); err != nil {
+		return err
+	}
+
+	if err := cfg.Save(g.Config); err != nil {
+		return err
+	}
+
+	return nil
+}