diff --git a/cmd/tokidoki/main.go b/cmd/tokidoki/main.go
index ea2ebb1..bdadce5 100644
--- a/cmd/tokidoki/main.go
+++ b/cmd/tokidoki/main.go
@@ -6,10 +6,12 @@ import (
 	"net/http"
 	"os"
 
+	"github.com/emersion/go-webdav/carddav"
 	"github.com/go-chi/chi/v5"
 	"github.com/go-chi/chi/v5/middleware"
 
 	"git.sr.ht/~sircmpwn/tokidoki/auth"
+	"git.sr.ht/~sircmpwn/tokidoki/storage"
 )
 
 func main() {
@@ -31,9 +33,8 @@ func main() {
 	authProvider := auth.NewIMAP("imap.migadu.com:993", true)
 	mux.Use(authProvider.Middleware())
 
-	mux.Get("/", func(w http.ResponseWriter, r *http.Request) {
-		w.Write([]byte("Hello world!\n"))
-	})
+	backend := storage.NewPostgreSQL()
+	mux.Handle("/", &carddav.Handler{Backend: backend})
 
 	server := http.Server{
 		Addr:    addr,
diff --git a/go.mod b/go.mod
index a516366..0a4b27f 100644
--- a/go.mod
+++ b/go.mod
@@ -5,6 +5,8 @@ go 1.17
 require (
 	github.com/emersion/go-imap v1.2.0 // indirect
 	github.com/emersion/go-sasl v0.0.0-20211008083017-0b9dcfb154ac // indirect
+	github.com/emersion/go-vcard v0.0.0-20210521075357-3445b9171995 // indirect
+	github.com/emersion/go-webdav v0.3.1 // indirect
 	github.com/go-chi/chi/v5 v5.0.7 // indirect
 	golang.org/x/text v0.3.7 // indirect
 )
diff --git a/go.sum b/go.sum
index 5086cd8..7089ed4 100644
--- a/go.sum
+++ b/go.sum
@@ -1,3 +1,4 @@
+github.com/emersion/go-ical v0.0.0-20200224201310-cd514449c39e/go.mod h1:4xVTBPcT43a1pp3vdaa+FuRdX5XhKCZPpWv7m0z9ByM=
 github.com/emersion/go-imap v1.2.0 h1:lyUQ3+EVM21/qbWE/4Ya5UG9r5+usDxlg4yfp3TgHFA=
 github.com/emersion/go-imap v1.2.0/go.mod h1:Qlx1FSx2FTxjnjWpIlVNEuX+ylerZQNFE5NsmKFSejY=
 github.com/emersion/go-message v0.15.0/go.mod h1:wQUEfE+38+7EW8p8aZ96ptg6bAb1iwdgej19uXASlE4=
@@ -5,6 +6,11 @@ github.com/emersion/go-sasl v0.0.0-20200509203442-7bfe0ed36a21/go.mod h1:iL2twTe
 github.com/emersion/go-sasl v0.0.0-20211008083017-0b9dcfb154ac h1:tn/OQ2PmwQ0XFVgAHfjlLyqMewry25Rz7jWnVoh4Ggs=
 github.com/emersion/go-sasl v0.0.0-20211008083017-0b9dcfb154ac/go.mod h1:iL2twTeMvZnrg54ZoPDNfJaJaqy0xIQFuBdrLsmspwQ=
 github.com/emersion/go-textwrapper v0.0.0-20200911093747-65d896831594/go.mod h1:aqO8z8wPrjkscevZJFVE1wXJrLpC5LtJG7fqLOsPb2U=
+github.com/emersion/go-vcard v0.0.0-20191221110513-5f81fa0d3cc7/go.mod h1:HMJKR5wlh/ziNp+sHEDV2ltblO4JD2+IdDOWtGcQBTM=
+github.com/emersion/go-vcard v0.0.0-20210521075357-3445b9171995 h1:DpVfmcoBs6o9VYcccNWbuKFQxuHCgt25/y4q9H8AUvc=
+github.com/emersion/go-vcard v0.0.0-20210521075357-3445b9171995/go.mod h1:HMJKR5wlh/ziNp+sHEDV2ltblO4JD2+IdDOWtGcQBTM=
+github.com/emersion/go-webdav v0.3.1 h1:8ISu6AlBwu7DKg9RQE3iRpE3CPM8Bfpfz7L3bi/xlGI=
+github.com/emersion/go-webdav v0.3.1/go.mod h1:uSM1VveeKtogBVWaYccTksToczooJ0rrVGNsgnDsr4Q=
 github.com/go-chi/chi/v5 v5.0.7 h1:rDTPXLDHGATaeHvVlLcR4Qe0zftYethFucbjVQ1PxU8=
 github.com/go-chi/chi/v5 v5.0.7/go.mod h1:DslCQbL2OYiznFReuXYUmQ2hGd1aDpCnlMNITLSKoi8=
 golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
diff --git a/storage/postgresql.go b/storage/postgresql.go
index e69de29..843a2d0 100644
--- a/storage/postgresql.go
+++ b/storage/postgresql.go
@@ -0,0 +1,38 @@
+package storage
+
+import (
+	"github.com/emersion/go-vcard"
+	"github.com/emersion/go-webdav/carddav"
+)
+
+type psqlBackend struct{}
+
+var _ carddav.Backend = (*psqlBackend)(nil)
+
+func NewPostgreSQL() carddav.Backend {
+	return &psqlBackend{}
+}
+
+func (*psqlBackend) AddressBook() (*carddav.AddressBook, error) {
+	panic("TODO")
+}
+
+func (*psqlBackend) GetAddressObject(path string, req *carddav.AddressDataRequest) (*carddav.AddressObject, error) {
+	panic("TODO")
+}
+
+func (*psqlBackend) ListAddressObjects(req *carddav.AddressDataRequest) ([]carddav.AddressObject, error) {
+	panic("TODO")
+}
+
+func (*psqlBackend) QueryAddressObjects(query *carddav.AddressBookQuery) ([]carddav.AddressObject, error) {
+	panic("TODO")
+}
+
+func (*psqlBackend) PutAddressObject(path string, card vcard.Card) (loc string, err error) {
+	panic("TODO")
+}
+
+func (*psqlBackend) DeleteAddressObject(path string) error {
+	panic("TODO")
+}