diff --git a/internal/client/repository.go b/internal/client/repository.go
new file mode 100644
index 0000000..c67d0d7
--- /dev/null
+++ b/internal/client/repository.go
@@ -0,0 +1,11 @@
+package client
+
+import (
+	"context"
+
+	"source.toby3d.me/website/oauth/internal/model"
+)
+
+type Repository interface {
+	Get(ctx context.Context, id string) (*model.Client, error)
+}
diff --git a/internal/client/usecase.go b/internal/client/usecase.go
new file mode 100644
index 0000000..8d006ba
--- /dev/null
+++ b/internal/client/usecase.go
@@ -0,0 +1,11 @@
+package client
+
+import (
+	"context"
+
+	"source.toby3d.me/website/oauth/internal/model"
+)
+
+type UseCase interface {
+	Discovery(ctx context.Context, clientID model.URL) (*model.Client, error)
+}
diff --git a/internal/client/usecase/client_ucase.go b/internal/client/usecase/client_ucase.go
new file mode 100644
index 0000000..e9e9705
--- /dev/null
+++ b/internal/client/usecase/client_ucase.go
@@ -0,0 +1,22 @@
+package usecase
+
+import (
+	"context"
+
+	"source.toby3d.me/website/oauth/internal/client"
+	"source.toby3d.me/website/oauth/internal/model"
+)
+
+type clientUseCase struct {
+	clients client.Repository
+}
+
+func NewClientUseCase(clients client.Repository) client.UseCase {
+	return &clientUseCase{
+		clients: clients,
+	}
+}
+
+func (useCase *clientUseCase) Discovery(ctx context.Context, clientID model.URL) (*model.Client, error) {
+	return useCase.clients.Get(ctx, string(clientID))
+}
diff --git a/internal/client/usecase/client_ucase_test.go b/internal/client/usecase/client_ucase_test.go
new file mode 100644
index 0000000..192b15a
--- /dev/null
+++ b/internal/client/usecase/client_ucase_test.go
@@ -0,0 +1,39 @@
+package usecase_test
+
+import (
+	"context"
+	"sync"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	repository "source.toby3d.me/website/oauth/internal/client/repository/memory"
+	"source.toby3d.me/website/oauth/internal/client/usecase"
+	"source.toby3d.me/website/oauth/internal/model"
+)
+
+func TestDiscovery(t *testing.T) {
+	t.Parallel()
+
+	require := require.New(t)
+	assert := assert.New(t)
+	store := new(sync.Map)
+	client := &model.Client{
+		ID:   "http://127.0.0.1:2368/",
+		Name: "Example App",
+		Logo: "http://127.0.0.1:2368/logo.png",
+		URL:  "http://127.0.0.1:2368/",
+		RedirectURI: []model.URL{
+			"https://app.example.com/redirect",
+			"http://127.0.0.1:2368/redirect",
+		},
+	}
+
+	store.Store(string(client.ID), client)
+
+	result, err := usecase.NewClientUseCase(repository.NewMemoryClientRepository(store)).Discovery(context.TODO(),
+		client.ID)
+	require.NoError(err)
+	assert.Equal(client, result)
+}