diff --git a/api/apierror/common.go b/api/apierror/common.go
index 2ccc7e7..c20b8fe 100644
--- a/api/apierror/common.go
+++ b/api/apierror/common.go
@@ -7,8 +7,8 @@ import (
 	"net/http"
 	"strings"
 
+	"github.com/Karaoke-Manager/karman/core"
 	"github.com/Karaoke-Manager/karman/pkg/render"
-	"github.com/Karaoke-Manager/karman/service"
 )
 
 // ProblemTypeDomain is the base domain for all custom problem types.
@@ -72,7 +72,7 @@ func JSONUnmarshalError(err *json.UnmarshalTypeError) *ProblemDetails {
 // This function maps known errors to their responses.
 func ServiceError(err error) *ProblemDetails {
 	switch {
-	case errors.Is(err, service.ErrNotFound):
+	case errors.Is(err, core.ErrNotFound):
 		return ErrNotFound
 	default:
 		return ErrInternalServerError
diff --git a/api/handler.go b/api/handler.go
index d5075ee..8199018 100644
--- a/api/handler.go
+++ b/api/handler.go
@@ -11,11 +11,11 @@ import (
 	"github.com/Karaoke-Manager/karman/api/apierror"
 	"github.com/Karaoke-Manager/karman/api/middleware"
 	v1 "github.com/Karaoke-Manager/karman/api/v1"
+	"github.com/Karaoke-Manager/karman/core/media"
+	"github.com/Karaoke-Manager/karman/core/song"
+	"github.com/Karaoke-Manager/karman/core/upload"
 	"github.com/Karaoke-Manager/karman/pkg/render"
 	_ "github.com/Karaoke-Manager/karman/pkg/render/json" // JSON encoding for responses
-	"github.com/Karaoke-Manager/karman/service/media"
-	"github.com/Karaoke-Manager/karman/service/song"
-	"github.com/Karaoke-Manager/karman/service/upload"
 )
 
 // HealthChecker is an interface that can provide information about the system health.
diff --git a/api/v1/dav/handler.go b/api/v1/dav/handler.go
index 2e578a8..1ac9943 100644
--- a/api/v1/dav/handler.go
+++ b/api/v1/dav/handler.go
@@ -8,8 +8,8 @@ import (
 	"golang.org/x/net/webdav"
 
 	"github.com/Karaoke-Manager/karman/api/v1/dav/internal"
-	"github.com/Karaoke-Manager/karman/service/media"
-	"github.com/Karaoke-Manager/karman/service/song"
+	"github.com/Karaoke-Manager/karman/core/media"
+	"github.com/Karaoke-Manager/karman/core/song"
 )
 
 func init() {
diff --git a/api/v1/dav/internal/filesystem.go b/api/v1/dav/internal/filesystem.go
index 5384030..ffcbe0e 100644
--- a/api/v1/dav/internal/filesystem.go
+++ b/api/v1/dav/internal/filesystem.go
@@ -11,10 +11,10 @@ import (
 	"github.com/google/uuid"
 	"golang.org/x/net/webdav"
 
+	"github.com/Karaoke-Manager/karman/core"
+	"github.com/Karaoke-Manager/karman/core/media"
+	songsvc "github.com/Karaoke-Manager/karman/core/song"
 	"github.com/Karaoke-Manager/karman/model"
-	"github.com/Karaoke-Manager/karman/service"
-	"github.com/Karaoke-Manager/karman/service/media"
-	songsvc "github.com/Karaoke-Manager/karman/service/song"
 )
 
 // flatFS implements a [webdav.FileSystem] that serves songs in a flat hierarchy:
@@ -76,7 +76,7 @@ func (s *flatFS) find(ctx context.Context, name string) (node, error) {
 	}
 
 	song, err := s.songRepo.GetSong(ctx, id)
-	if errors.Is(err, service.ErrNotFound) {
+	if errors.Is(err, core.ErrNotFound) {
 		return nil, fs.ErrNotExist
 	} else if err != nil {
 		return nil, err
diff --git a/api/v1/dav/internal/mediafile.go b/api/v1/dav/internal/mediafile.go
index bee7115..1ee9452 100644
--- a/api/v1/dav/internal/mediafile.go
+++ b/api/v1/dav/internal/mediafile.go
@@ -9,11 +9,11 @@ import (
 
 	"golang.org/x/net/webdav"
 
+	"github.com/Karaoke-Manager/karman/core/media"
+	"github.com/Karaoke-Manager/karman/core/song"
 	"github.com/Karaoke-Manager/karman/model"
 	"github.com/Karaoke-Manager/karman/pkg/mediatype"
 	"github.com/Karaoke-Manager/karman/pkg/streamio"
-	"github.com/Karaoke-Manager/karman/service/media"
-	"github.com/Karaoke-Manager/karman/service/song"
 )
 
 // mediaNode is a node representing a media file.
diff --git a/api/v1/dav/internal/root.go b/api/v1/dav/internal/root.go
index 05de957..f4ad356 100644
--- a/api/v1/dav/internal/root.go
+++ b/api/v1/dav/internal/root.go
@@ -10,8 +10,8 @@ import (
 
 	"golang.org/x/net/webdav"
 
-	"github.com/Karaoke-Manager/karman/service/media"
-	songsvc "github.com/Karaoke-Manager/karman/service/song"
+	"github.com/Karaoke-Manager/karman/core/media"
+	songsvc "github.com/Karaoke-Manager/karman/core/song"
 )
 
 // rootNode represents the root directory of a flatFS.
diff --git a/api/v1/dav/internal/songdir.go b/api/v1/dav/internal/songdir.go
index 13c470f..4dea4ea 100644
--- a/api/v1/dav/internal/songdir.go
+++ b/api/v1/dav/internal/songdir.go
@@ -10,9 +10,9 @@ import (
 
 	"golang.org/x/net/webdav"
 
+	"github.com/Karaoke-Manager/karman/core/media"
+	"github.com/Karaoke-Manager/karman/core/song"
 	"github.com/Karaoke-Manager/karman/model"
-	"github.com/Karaoke-Manager/karman/service/media"
-	"github.com/Karaoke-Manager/karman/service/song"
 )
 
 // songNode represents the directory for a song.
diff --git a/api/v1/dav/internal/txtfile.go b/api/v1/dav/internal/txtfile.go
index 8342b3b..52e6b9e 100644
--- a/api/v1/dav/internal/txtfile.go
+++ b/api/v1/dav/internal/txtfile.go
@@ -11,9 +11,9 @@ import (
 	"codello.dev/ultrastar/txt"
 	"golang.org/x/net/webdav"
 
+	"github.com/Karaoke-Manager/karman/core/media"
+	"github.com/Karaoke-Manager/karman/core/song"
 	"github.com/Karaoke-Manager/karman/model"
-	"github.com/Karaoke-Manager/karman/service/media"
-	"github.com/Karaoke-Manager/karman/service/song"
 )
 
 // txtNode represents the TXT file for a song.
diff --git a/api/v1/handler.go b/api/v1/handler.go
index 5e9cd3b..7ba8dd6 100644
--- a/api/v1/handler.go
+++ b/api/v1/handler.go
@@ -9,9 +9,9 @@ import (
 	"github.com/Karaoke-Manager/karman/api/v1/dav"
 	"github.com/Karaoke-Manager/karman/api/v1/songs"
 	"github.com/Karaoke-Manager/karman/api/v1/uploads"
-	"github.com/Karaoke-Manager/karman/service/media"
-	"github.com/Karaoke-Manager/karman/service/song"
-	"github.com/Karaoke-Manager/karman/service/upload"
+	"github.com/Karaoke-Manager/karman/core/media"
+	"github.com/Karaoke-Manager/karman/core/song"
+	"github.com/Karaoke-Manager/karman/core/upload"
 )
 
 // Handler implements the /v1 API namespace.
diff --git a/api/v1/songs/handler.go b/api/v1/songs/handler.go
index c886980..72070ad 100644
--- a/api/v1/songs/handler.go
+++ b/api/v1/songs/handler.go
@@ -7,9 +7,9 @@ import (
 	"github.com/go-chi/chi/v5"
 
 	"github.com/Karaoke-Manager/karman/api/middleware"
+	"github.com/Karaoke-Manager/karman/core/media"
+	"github.com/Karaoke-Manager/karman/core/song"
 	"github.com/Karaoke-Manager/karman/pkg/render"
-	"github.com/Karaoke-Manager/karman/service/media"
-	"github.com/Karaoke-Manager/karman/service/song"
 )
 
 // Handler implements the /v1/songs endpoints.
diff --git a/api/v1/songs/handler_test.go b/api/v1/songs/handler_test.go
index a68d521..054c264 100644
--- a/api/v1/songs/handler_test.go
+++ b/api/v1/songs/handler_test.go
@@ -14,10 +14,10 @@ import (
 	"github.com/jackc/pgxutil"
 
 	"github.com/Karaoke-Manager/karman/api/apierror"
+	"github.com/Karaoke-Manager/karman/core/media"
+	"github.com/Karaoke-Manager/karman/core/song"
 	"github.com/Karaoke-Manager/karman/pkg/nolog"
 	_ "github.com/Karaoke-Manager/karman/pkg/render/json"
-	"github.com/Karaoke-Manager/karman/service/media"
-	"github.com/Karaoke-Manager/karman/service/song"
 	"github.com/Karaoke-Manager/karman/test"
 )
 
diff --git a/api/v1/songs/media_test.go b/api/v1/songs/media_test.go
index f48a550..aad356a 100644
--- a/api/v1/songs/media_test.go
+++ b/api/v1/songs/media_test.go
@@ -17,9 +17,9 @@ import (
 
 	"github.com/Karaoke-Manager/karman/api/apierror"
 	"github.com/Karaoke-Manager/karman/api/schema"
+	"github.com/Karaoke-Manager/karman/core/media"
 	"github.com/Karaoke-Manager/karman/model"
 	"github.com/Karaoke-Manager/karman/pkg/mediatype"
-	"github.com/Karaoke-Manager/karman/service/media"
 	"github.com/Karaoke-Manager/karman/test"
 	testdata "github.com/Karaoke-Manager/karman/test/data"
 )
diff --git a/api/v1/uploads/file_crud.go b/api/v1/uploads/file_crud.go
index b80e2ba..ba8484c 100644
--- a/api/v1/uploads/file_crud.go
+++ b/api/v1/uploads/file_crud.go
@@ -10,8 +10,8 @@ import (
 
 	"github.com/Karaoke-Manager/karman/api/apierror"
 	"github.com/Karaoke-Manager/karman/api/schema"
+	"github.com/Karaoke-Manager/karman/core/upload"
 	"github.com/Karaoke-Manager/karman/pkg/render"
-	"github.com/Karaoke-Manager/karman/service/upload"
 )
 
 // PutFile implements the PUT /v1/uploads/{uuid}/files/* endpoint.
diff --git a/api/v1/uploads/handler.go b/api/v1/uploads/handler.go
index c94a2fb..9f16e21 100644
--- a/api/v1/uploads/handler.go
+++ b/api/v1/uploads/handler.go
@@ -7,9 +7,9 @@ import (
 	"github.com/go-chi/chi/v5"
 
 	"github.com/Karaoke-Manager/karman/api/middleware"
+	"github.com/Karaoke-Manager/karman/core/upload"
 	"github.com/Karaoke-Manager/karman/model"
 	"github.com/Karaoke-Manager/karman/pkg/render"
-	"github.com/Karaoke-Manager/karman/service/upload"
 )
 
 // Handler implements the /v1/uploads endpoints.
diff --git a/api/v1/uploads/handler_test.go b/api/v1/uploads/handler_test.go
index ecfa418..1391523 100644
--- a/api/v1/uploads/handler_test.go
+++ b/api/v1/uploads/handler_test.go
@@ -17,9 +17,9 @@ import (
 	"github.com/jackc/pgxutil"
 
 	"github.com/Karaoke-Manager/karman/api/apierror"
+	"github.com/Karaoke-Manager/karman/core/upload"
 	"github.com/Karaoke-Manager/karman/pkg/nolog"
 	_ "github.com/Karaoke-Manager/karman/pkg/render/json"
-	"github.com/Karaoke-Manager/karman/service/upload"
 	"github.com/Karaoke-Manager/karman/test"
 )
 
diff --git a/cmd/karman/server.go b/cmd/karman/server.go
index 932a2a7..61b8d19 100644
--- a/cmd/karman/server.go
+++ b/cmd/karman/server.go
@@ -23,10 +23,10 @@ import (
 
 	"github.com/Karaoke-Manager/karman/api"
 	"github.com/Karaoke-Manager/karman/cmd/karman/internal"
+	"github.com/Karaoke-Manager/karman/core/media"
+	"github.com/Karaoke-Manager/karman/core/song"
+	"github.com/Karaoke-Manager/karman/core/upload"
 	"github.com/Karaoke-Manager/karman/migrations"
-	"github.com/Karaoke-Manager/karman/service/media"
-	"github.com/Karaoke-Manager/karman/service/song"
-	"github.com/Karaoke-Manager/karman/service/upload"
 )
 
 // serverCmd implements the "server" command.
diff --git a/service/doc.go b/core/doc.go
similarity index 69%
rename from service/doc.go
rename to core/doc.go
index d9643f4..aa2e6ae 100644
--- a/service/doc.go
+++ b/core/doc.go
@@ -1,4 +1,4 @@
-// Package service is the root package for the domain logic of Karman.
+// Package core is the root package for the domain logic of Karman.
 // This package itself contains only some shared utilities used by different service implementations.
 // Sub-packages of this package contain the actual service definitions and implementations.
-package service
+package core
diff --git a/service/errors.go b/core/errors.go
similarity index 89%
rename from service/errors.go
rename to core/errors.go
index 74283d6..ea15d43 100644
--- a/service/errors.go
+++ b/core/errors.go
@@ -1,4 +1,4 @@
-package service
+package core
 
 import (
 	"errors"
diff --git a/service/dbutil/errors.go b/core/internal/dbutil/errors.go
similarity index 66%
rename from service/dbutil/errors.go
rename to core/internal/dbutil/errors.go
index 7be1643..616e857 100644
--- a/service/dbutil/errors.go
+++ b/core/internal/dbutil/errors.go
@@ -5,12 +5,12 @@ import (
 
 	"github.com/jackc/pgx/v5"
 
-	"github.com/Karaoke-Manager/karman/service"
+	"github.com/Karaoke-Manager/karman/core"
 )
 
 func Error(err error) error {
 	if errors.Is(err, pgx.ErrNoRows) {
-		return service.ErrNotFound
+		return core.ErrNotFound
 	}
 	return err
 }
diff --git a/service/dbutil/notes.go b/core/internal/dbutil/notes.go
similarity index 100%
rename from service/dbutil/notes.go
rename to core/internal/dbutil/notes.go
diff --git a/service/dbutil/zero.go b/core/internal/dbutil/zero.go
similarity index 100%
rename from service/dbutil/zero.go
rename to core/internal/dbutil/zero.go
diff --git a/service/dbutil/zero_test.go b/core/internal/dbutil/zero_test.go
similarity index 100%
rename from service/dbutil/zero_test.go
rename to core/internal/dbutil/zero_test.go
diff --git a/service/media/fakerepo.go b/core/media/fakerepo.go
similarity index 92%
rename from service/media/fakerepo.go
rename to core/media/fakerepo.go
index bee6d42..f53c7eb 100644
--- a/service/media/fakerepo.go
+++ b/core/media/fakerepo.go
@@ -6,8 +6,8 @@ import (
 
 	"github.com/google/uuid"
 
+	"github.com/Karaoke-Manager/karman/core"
 	"github.com/Karaoke-Manager/karman/model"
-	svc "github.com/Karaoke-Manager/karman/service"
 )
 
 // fakeRepo is a Repository implementation backed by an in-memory map.
@@ -32,7 +32,7 @@ func (f fakeRepo) CreateFile(_ context.Context, file *model.File) error {
 // UpdateFile updates the stored version of file.
 func (f fakeRepo) UpdateFile(_ context.Context, file *model.File) error {
 	if _, ok := f.files[file.UUID]; !ok {
-		return svc.ErrNotFound
+		return core.ErrNotFound
 	}
 	file.UpdatedAt = time.Now()
 	f.files[file.UUID] = *file
diff --git a/service/media/fakerepo_test.go b/core/media/fakerepo_test.go
similarity index 94%
rename from service/media/fakerepo_test.go
rename to core/media/fakerepo_test.go
index 8de0cca..a8bf295 100644
--- a/service/media/fakerepo_test.go
+++ b/core/media/fakerepo_test.go
@@ -7,9 +7,9 @@ import (
 
 	"github.com/google/uuid"
 
+	"github.com/Karaoke-Manager/karman/core"
 	"github.com/Karaoke-Manager/karman/model"
 	"github.com/Karaoke-Manager/karman/pkg/mediatype"
-	svc "github.com/Karaoke-Manager/karman/service"
 )
 
 func Test_fakeRepo_CreateFile(t *testing.T) {
@@ -59,7 +59,7 @@ func Test_fakeRepo_UpdateFile(t *testing.T) {
 			Model: model.Model{UUID: uuid.New()},
 		}
 		err := repo.UpdateFile(context.TODO(), &update)
-		if !errors.Is(err, svc.ErrNotFound) {
+		if !errors.Is(err, core.ErrNotFound) {
 			t.Errorf("UpdateFile(ctx, &update) returned an unexpected error: %s, expected ErrNotFound", err)
 		}
 	})
diff --git a/service/media/fakeservice.go b/core/media/fakeservice.go
similarity index 77%
rename from service/media/fakeservice.go
rename to core/media/fakeservice.go
index 68d0758..b840020 100644
--- a/service/media/fakeservice.go
+++ b/core/media/fakeservice.go
@@ -10,21 +10,21 @@ import (
 	"github.com/Karaoke-Manager/karman/pkg/mediatype"
 )
 
-// FakeService is a Service implementation that only uses dummy values for file contents.
+// fakeService is a Service implementation that only uses dummy values for file contents.
 // This type is intended for testing purposes.
-type FakeService struct {
+type fakeService struct {
 	repo Repository
 }
 
-// NewFakeService creates a new FakeService instance and returns it.
+// NewFakeService creates a new fakeService instance and returns it.
 // The placeholder will be the content of all "files".
 func NewFakeService(repo Repository) Service {
-	return &FakeService{repo}
+	return &fakeService{repo}
 }
 
 // StoreFile fully reads r and returns a file with dummy values.
 // file.Type will be set to mediaType.
-func (f *FakeService) StoreFile(ctx context.Context, mediaType mediatype.MediaType, r io.Reader) (model.File, error) {
+func (f *fakeService) StoreFile(ctx context.Context, mediaType mediatype.MediaType, r io.Reader) (model.File, error) {
 	h := sha256.New()
 	n, err := io.Copy(h, r)
 	if err != nil {
diff --git a/service/media/fakeservice_test.go b/core/media/fakeservice_test.go
similarity index 100%
rename from service/media/fakeservice_test.go
rename to core/media/fakeservice_test.go
diff --git a/service/media/filestore.go b/core/media/filestore.go
similarity index 100%
rename from service/media/filestore.go
rename to core/media/filestore.go
diff --git a/service/media/filestore_test.go b/core/media/filestore_test.go
similarity index 100%
rename from service/media/filestore_test.go
rename to core/media/filestore_test.go
diff --git a/service/media/interface.go b/core/media/interface.go
similarity index 100%
rename from service/media/interface.go
rename to core/media/interface.go
diff --git a/service/media/memstore.go b/core/media/memstore.go
similarity index 100%
rename from service/media/memstore.go
rename to core/media/memstore.go
diff --git a/service/media/memstore_test.go b/core/media/memstore_test.go
similarity index 100%
rename from service/media/memstore_test.go
rename to core/media/memstore_test.go
diff --git a/service/media/mockstore.go b/core/media/mockstore.go
similarity index 100%
rename from service/media/mockstore.go
rename to core/media/mockstore.go
diff --git a/service/media/mockstore_test.go b/core/media/mockstore_test.go
similarity index 100%
rename from service/media/mockstore_test.go
rename to core/media/mockstore_test.go
diff --git a/service/media/repo.go b/core/media/repo.go
similarity index 97%
rename from service/media/repo.go
rename to core/media/repo.go
index f7774dd..e8e9dfe 100644
--- a/service/media/repo.go
+++ b/core/media/repo.go
@@ -11,8 +11,8 @@ import (
 	"github.com/jackc/pgxutil"
 	"github.com/lmittmann/tint"
 
+	"github.com/Karaoke-Manager/karman/core/internal/dbutil"
 	"github.com/Karaoke-Manager/karman/model"
-	"github.com/Karaoke-Manager/karman/service/dbutil"
 )
 
 // dbRepo is a Repository implementation backed by a PostgreSQL database.
diff --git a/service/media/repo_test.go b/core/media/repo_test.go
similarity index 96%
rename from service/media/repo_test.go
rename to core/media/repo_test.go
index 64a1dd5..6544666 100644
--- a/service/media/repo_test.go
+++ b/core/media/repo_test.go
@@ -9,10 +9,10 @@ import (
 
 	"github.com/google/uuid"
 
+	"github.com/Karaoke-Manager/karman/core"
 	"github.com/Karaoke-Manager/karman/model"
 	"github.com/Karaoke-Manager/karman/pkg/mediatype"
 	"github.com/Karaoke-Manager/karman/pkg/nolog"
-	svc "github.com/Karaoke-Manager/karman/service"
 	"github.com/Karaoke-Manager/karman/test"
 	testdata "github.com/Karaoke-Manager/karman/test/data"
 )
@@ -89,7 +89,7 @@ func Test_dbRepo_UpdateFile(t *testing.T) {
 		file := model.File{}
 		file.UUID = uuid.New()
 		err := repo.UpdateFile(context.TODO(), &file)
-		if !errors.Is(err, svc.ErrNotFound) {
+		if !errors.Is(err, core.ErrNotFound) {
 			t.Errorf("UpdateFile(ctx, &file) returned an unexpected error: %s, expected ErrNotFound", err)
 		}
 	})
diff --git a/service/media/service.go b/core/media/service.go
similarity index 100%
rename from service/media/service.go
rename to core/media/service.go
diff --git a/service/media/service_test.go b/core/media/service_test.go
similarity index 100%
rename from service/media/service_test.go
rename to core/media/service_test.go
diff --git a/service/media/task.go b/core/media/task.go
similarity index 100%
rename from service/media/task.go
rename to core/media/task.go
diff --git a/service/media/testdata/test.gif b/core/media/testdata/test.gif
similarity index 100%
rename from service/media/testdata/test.gif
rename to core/media/testdata/test.gif
diff --git a/service/media/testdata/test.jpg b/core/media/testdata/test.jpg
similarity index 100%
rename from service/media/testdata/test.jpg
rename to core/media/testdata/test.jpg
diff --git a/service/media/testdata/test.mp3 b/core/media/testdata/test.mp3
similarity index 100%
rename from service/media/testdata/test.mp3
rename to core/media/testdata/test.mp3
diff --git a/service/media/testdata/test.mp4 b/core/media/testdata/test.mp4
similarity index 100%
rename from service/media/testdata/test.mp4
rename to core/media/testdata/test.mp4
diff --git a/service/media/testdata/test.png b/core/media/testdata/test.png
similarity index 100%
rename from service/media/testdata/test.png
rename to core/media/testdata/test.png
diff --git a/service/song/fakerepo.go b/core/song/fakerepo.go
similarity index 94%
rename from service/song/fakerepo.go
rename to core/song/fakerepo.go
index 2610963..68edd14 100644
--- a/service/song/fakerepo.go
+++ b/core/song/fakerepo.go
@@ -7,8 +7,8 @@ import (
 
 	"github.com/google/uuid"
 
+	"github.com/Karaoke-Manager/karman/core"
 	"github.com/Karaoke-Manager/karman/model"
-	svc "github.com/Karaoke-Manager/karman/service"
 )
 
 // fakeRepo is a simple implementation of Repository that can be used for testing.
@@ -36,7 +36,7 @@ func (r *fakeRepo) CreateSong(_ context.Context, song *model.Song) error {
 func (r *fakeRepo) GetSong(_ context.Context, id uuid.UUID) (model.Song, error) {
 	song, ok := r.songs[id]
 	if !ok {
-		return model.Song{}, svc.ErrNotFound
+		return model.Song{}, core.ErrNotFound
 	}
 	return song, nil
 }
@@ -73,7 +73,7 @@ func (r *fakeRepo) DeleteSong(_ context.Context, id uuid.UUID) (bool, error) {
 func (r *fakeRepo) UpdateSong(_ context.Context, song *model.Song) error {
 	_, ok := r.songs[song.UUID]
 	if !ok {
-		return svc.ErrNotFound
+		return core.ErrNotFound
 	}
 	song.UpdatedAt = time.Now()
 	r.songs[song.UUID] = *song
diff --git a/service/song/fakerepo_test.go b/core/song/fakerepo_test.go
similarity index 96%
rename from service/song/fakerepo_test.go
rename to core/song/fakerepo_test.go
index b67346a..5d1ed84 100644
--- a/service/song/fakerepo_test.go
+++ b/core/song/fakerepo_test.go
@@ -7,8 +7,8 @@ import (
 
 	"github.com/google/uuid"
 
+	"github.com/Karaoke-Manager/karman/core"
 	"github.com/Karaoke-Manager/karman/model"
-	svc "github.com/Karaoke-Manager/karman/service"
 )
 
 func Test_fakeRepo_CreateSong(t *testing.T) {
@@ -55,7 +55,7 @@ func Test_fakeRepo_GetSong(t *testing.T) {
 	t.Run("missing", func(t *testing.T) {
 		id := uuid.New()
 		_, err := repo.GetSong(context.TODO(), id)
-		if !errors.Is(err, svc.ErrNotFound) {
+		if !errors.Is(err, core.ErrNotFound) {
 			t.Errorf("GetSong(ctx, %q) produced an unexpected error: %s, expected ErrNotFound", id, err)
 		}
 	})
@@ -147,7 +147,7 @@ func Test_fakeRepo_UpdateSong(t *testing.T) {
 			Model: model.Model{UUID: uuid.New()},
 		}
 		err := repo.UpdateSong(context.TODO(), &update)
-		if !errors.Is(err, svc.ErrNotFound) {
+		if !errors.Is(err, core.ErrNotFound) {
 			t.Errorf("UpdateSong(ctx, &update) returned an unexpected error: %s, expected ErrNotFound", err)
 		}
 	})
diff --git a/service/song/interface.go b/core/song/interface.go
similarity index 95%
rename from service/song/interface.go
rename to core/song/interface.go
index 6014e8a..3a8d30e 100644
--- a/service/song/interface.go
+++ b/core/song/interface.go
@@ -16,7 +16,7 @@ type Repository interface {
 	CreateSong(ctx context.Context, song *model.Song) error
 
 	// GetSong fetches the song with the specified UUID.
-	// If no such song exists, service.ErrNotFound will be returned.
+	// If no such song exists, core.ErrNotFound will be returned.
 	GetSong(ctx context.Context, id uuid.UUID) (model.Song, error)
 
 	// FindSongs returns all songs matching the specified query.
@@ -27,7 +27,7 @@ type Repository interface {
 	FindSongs(ctx context.Context, limit int, offset int64) ([]model.Song, int64, error)
 
 	// UpdateSong saves Updates for the specified song.
-	// The song's UUID must already exist in the database, otherwise e service.ErrNotFound
+	// The song's UUID must already exist in the database, otherwise e core.ErrNotFound
 	// will be returned.
 	UpdateSong(ctx context.Context, song *model.Song) error
 
diff --git a/service/song/repo.go b/core/song/repo.go
similarity index 99%
rename from service/song/repo.go
rename to core/song/repo.go
index 5106b09..38f6e7f 100644
--- a/service/song/repo.go
+++ b/core/song/repo.go
@@ -13,9 +13,9 @@ import (
 	"github.com/jackc/pgxutil"
 	"github.com/lmittmann/tint"
 
+	"github.com/Karaoke-Manager/karman/core/internal/dbutil"
 	"github.com/Karaoke-Manager/karman/model"
 	"github.com/Karaoke-Manager/karman/pkg/mediatype"
-	"github.com/Karaoke-Manager/karman/service/dbutil"
 )
 
 // dbRepo is the main Repository implementation, backed by a PostgreSQL database.
diff --git a/service/song/repo_test.go b/core/song/repo_test.go
similarity index 97%
rename from service/song/repo_test.go
rename to core/song/repo_test.go
index d5b5c78..ee13654 100644
--- a/service/song/repo_test.go
+++ b/core/song/repo_test.go
@@ -10,10 +10,10 @@ import (
 
 	"github.com/google/uuid"
 
+	"github.com/Karaoke-Manager/karman/core"
 	"github.com/Karaoke-Manager/karman/model"
 	"github.com/Karaoke-Manager/karman/pkg/mediatype"
 	"github.com/Karaoke-Manager/karman/pkg/nolog"
-	svc "github.com/Karaoke-Manager/karman/service"
 	"github.com/Karaoke-Manager/karman/test"
 	testdata "github.com/Karaoke-Manager/karman/test/data"
 )
@@ -88,7 +88,7 @@ func Test_dbRepo_GetSong(t *testing.T) {
 		_, err := repo.GetSong(context.TODO(), id)
 		if err == nil {
 			t.Errorf("GetSong(ctx, %q) did not return an error, expected ErrNotFound", id)
-		} else if !errors.Is(err, svc.ErrNotFound) {
+		} else if !errors.Is(err, core.ErrNotFound) {
 			t.Errorf("GetSong(ctx, %q) returned an unexpected error: %s", id, err)
 		}
 	})
@@ -140,7 +140,7 @@ func Test_dbRepo_UpdateSong(t *testing.T) {
 		song := model.Song{}
 		song.UUID = uuid.New()
 		err := repo.UpdateSong(context.TODO(), &song)
-		if !errors.Is(err, svc.ErrNotFound) {
+		if !errors.Is(err, core.ErrNotFound) {
 			t.Errorf("UpdateSong(ctx, &song) returned an unexpected error: %s, expected ErrNotFound", err)
 		}
 	})
diff --git a/service/song/service.go b/core/song/service.go
similarity index 100%
rename from service/song/service.go
rename to core/song/service.go
diff --git a/service/song/service_test.go b/core/song/service_test.go
similarity index 100%
rename from service/song/service_test.go
rename to core/song/service_test.go
diff --git a/service/upload/filestore.go b/core/upload/filestore.go
similarity index 100%
rename from service/upload/filestore.go
rename to core/upload/filestore.go
diff --git a/service/upload/filestore_test.go b/core/upload/filestore_test.go
similarity index 100%
rename from service/upload/filestore_test.go
rename to core/upload/filestore_test.go
diff --git a/service/upload/interface.go b/core/upload/interface.go
similarity index 100%
rename from service/upload/interface.go
rename to core/upload/interface.go
diff --git a/service/upload/repo.go b/core/upload/repo.go
similarity index 98%
rename from service/upload/repo.go
rename to core/upload/repo.go
index 2387f3e..ed8c2f7 100644
--- a/service/upload/repo.go
+++ b/core/upload/repo.go
@@ -12,8 +12,8 @@ import (
 	"github.com/jackc/pgxutil"
 	"github.com/lmittmann/tint"
 
+	"github.com/Karaoke-Manager/karman/core/internal/dbutil"
 	"github.com/Karaoke-Manager/karman/model"
-	"github.com/Karaoke-Manager/karman/service/dbutil"
 )
 
 // dbRepo is the main Repository implementation, backed by a PostgreSQL database.
diff --git a/service/upload/repo_test.go b/core/upload/repo_test.go
similarity index 97%
rename from service/upload/repo_test.go
rename to core/upload/repo_test.go
index 2ee5e3e..997b656 100644
--- a/service/upload/repo_test.go
+++ b/core/upload/repo_test.go
@@ -9,9 +9,9 @@ import (
 
 	"github.com/google/uuid"
 
+	"github.com/Karaoke-Manager/karman/core"
 	"github.com/Karaoke-Manager/karman/model"
 	"github.com/Karaoke-Manager/karman/pkg/nolog"
-	svc "github.com/Karaoke-Manager/karman/service"
 	"github.com/Karaoke-Manager/karman/test"
 	testdata "github.com/Karaoke-Manager/karman/test/data"
 )
@@ -47,7 +47,7 @@ func TestService_GetUpload(t *testing.T) {
 		if err == nil {
 			t.Errorf("GetUpload(ctx, %q) did not return an error, expected ErrNotFound", id)
 		}
-		if !errors.Is(err, svc.ErrNotFound) {
+		if !errors.Is(err, core.ErrNotFound) {
 			t.Errorf("GetUpload(ctx, %q) returned an unexpected error: %s", id, err)
 		}
 	})
@@ -127,7 +127,7 @@ func TestService_DeleteUpload(t *testing.T) {
 		}
 
 		_, err = repo.GetUpload(context.TODO(), upload.UUID)
-		if !errors.Is(err, svc.ErrNotFound) {
+		if !errors.Is(err, core.ErrNotFound) {
 			t.Errorf("GetUpload(ctx, %q) returned an upload after it was deleted", upload.UUID)
 		}
 	})
diff --git a/service/upload/testdata/e4d7ec99-77e0-4595-815a-18f3811c1b9d/dir1/.gitkeep b/core/upload/testdata/e4d7ec99-77e0-4595-815a-18f3811c1b9d/dir1/.gitkeep
similarity index 100%
rename from service/upload/testdata/e4d7ec99-77e0-4595-815a-18f3811c1b9d/dir1/.gitkeep
rename to core/upload/testdata/e4d7ec99-77e0-4595-815a-18f3811c1b9d/dir1/.gitkeep
diff --git a/service/upload/testdata/e4d7ec99-77e0-4595-815a-18f3811c1b9d/dir2/.gitkeep b/core/upload/testdata/e4d7ec99-77e0-4595-815a-18f3811c1b9d/dir2/.gitkeep
similarity index 100%
rename from service/upload/testdata/e4d7ec99-77e0-4595-815a-18f3811c1b9d/dir2/.gitkeep
rename to core/upload/testdata/e4d7ec99-77e0-4595-815a-18f3811c1b9d/dir2/.gitkeep
diff --git a/service/upload/testdata/e4d7ec99-77e0-4595-815a-18f3811c1b9d/file1.txt b/core/upload/testdata/e4d7ec99-77e0-4595-815a-18f3811c1b9d/file1.txt
similarity index 100%
rename from service/upload/testdata/e4d7ec99-77e0-4595-815a-18f3811c1b9d/file1.txt
rename to core/upload/testdata/e4d7ec99-77e0-4595-815a-18f3811c1b9d/file1.txt
diff --git a/service/upload/testdata/e4d7ec99-77e0-4595-815a-18f3811c1b9d/file2.txt b/core/upload/testdata/e4d7ec99-77e0-4595-815a-18f3811c1b9d/file2.txt
similarity index 100%
rename from service/upload/testdata/e4d7ec99-77e0-4595-815a-18f3811c1b9d/file2.txt
rename to core/upload/testdata/e4d7ec99-77e0-4595-815a-18f3811c1b9d/file2.txt
diff --git a/pkg/nolog/handler.go b/pkg/nolog/handler.go
index f54baee..f060d85 100644
--- a/pkg/nolog/handler.go
+++ b/pkg/nolog/handler.go
@@ -5,9 +5,13 @@ import (
 	"log/slog"
 )
 
+// Handler is a noop logging handler.
 var Handler slog.Handler = &handler{}
+
+// Logger is a noop logger.
 var Logger = slog.New(Handler)
 
+// handler implements a noop slog.Handler.
 type handler struct{}
 
 // Enabled returns false for all log levels.