diff --git a/app/main.go b/app/main.go
index a8de035d..6cb4ce37 100644
--- a/app/main.go
+++ b/app/main.go
@@ -26,6 +26,7 @@ var opts struct {
 	Dbg     bool `long:"dbg" env:"DEBUG" description:"debug mode"`
 
 	BackupLocation string `long:"backup" env:"BACKUP_PATH" default:"/tmp" description:"backups location"`
+	MaxBackupFiles int    `long:"max-back" env:"MAX_BACKUP_FILES" default:"10" description:"max backups to keep"`
 
 	ServerCommand struct {
 		SessionStore string `long:"session" env:"SESSION_STORE" default:"/tmp" description:"path to session store directory"`
@@ -112,7 +113,10 @@ func main() {
 		log.Printf("[WARN] running in dev mode, no auth!")
 	}
 
-	go migrator.AutoBackup(&exporter, opts.BackupLocation)
+	for _, siteID := range opts.Sites {
+		go migrator.AutoBackup(&exporter, opts.BackupLocation, siteID, opts.MaxBackupFiles)
+	}
+
 	srv.Run()
 }
 
diff --git a/app/migrator/migrator.go b/app/migrator/migrator.go
index 412d50ce..baeb1243 100644
--- a/app/migrator/migrator.go
+++ b/app/migrator/migrator.go
@@ -4,8 +4,11 @@ import (
 	"compress/gzip"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"log"
 	"os"
+	"sort"
+	"strings"
 	"time"
 
 	"github.com/pkg/errors"
@@ -59,22 +62,50 @@ func ImportComments(p ImportParams) error {
 }
 
 // AutoBackup runs daily export to local files
-func AutoBackup(exporter Exporter, backupLocation string) {
+func AutoBackup(exporter Exporter, backupLocation string, siteID string, keepMax int) {
 	log.Print("[INFO] activate auto-backup")
 	tick := time.NewTicker(24 * time.Hour)
 	for range tick.C {
 		log.Print("[DEBUG] make backup")
-		fh, err := os.Create(fmt.Sprintf("%s/backup-%s.gz", backupLocation, time.Now().Format("20060102")))
+		fh, err := os.Create(fmt.Sprintf("%s/backup-%s-%s.gz", backupLocation, siteID, time.Now().Format("20060102")))
 		if err != nil {
 			log.Printf("[WARN] can't create backup file, %s", err)
 			continue
 		}
 		gz := gzip.NewWriter(fh)
 
-		if err = exporter.Export(gz, ""); err != nil {
+		if err = exporter.Export(gz, siteID); err != nil {
 			log.Printf("[WARN] export failed, %+v", err)
 		}
 		_ = gz.Close()
 		_ = fh.Close()
+
+		removeOldBackupFiles(backupLocation, siteID, keepMax)
+	}
+}
+
+func removeOldBackupFiles(backupLocation string, siteID string, keepMax int) {
+	files, err := ioutil.ReadDir(backupLocation)
+	if err != nil {
+		log.Printf("[WARN] can't read files in backup directory %s, %s", backupLocation, err)
+		return
+	}
+	backFiles := []os.FileInfo{}
+	for _, file := range files {
+		if strings.HasPrefix(file.Name(), "backup-"+siteID) {
+			backFiles = append(backFiles, file)
+		}
+	}
+	sort.Slice(backFiles, func(i int, j int) bool { return backFiles[i].Name() < backFiles[j].Name() })
+
+	if len(backFiles) > keepMax {
+		for i := 0; i < len(backFiles)-keepMax; i++ {
+			fpath := backupLocation + "/" + backFiles[i].Name()
+			if e := os.Remove(fpath); e != nil {
+				log.Printf("[WARN] can't delete %s, %s", fpath, err)
+				continue
+			}
+			log.Printf("[DEBUG] removed %s", fpath)
+		}
 	}
 }
diff --git a/app/migrator/migrator_test.go b/app/migrator/migrator_test.go
new file mode 100644
index 00000000..8e1db7e7
--- /dev/null
+++ b/app/migrator/migrator_test.go
@@ -0,0 +1,30 @@
+package migrator
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestMigrator_RemoveOldBackupFiles(t *testing.T) {
+	loc := "tmp/remark-backups.test"
+	defer os.RemoveAll(loc)
+
+	os.MkdirAll(loc, 0700)
+	for i := 0; i < 10; i++ {
+		fname := fmt.Sprintf("%s/backup-site1-201712%02d.gz", loc, i)
+		err := ioutil.WriteFile(fname, []byte("blah"), 0600)
+		assert.Nil(t, err)
+	}
+
+	removeOldBackupFiles(loc, "site1", 3)
+	ff, err := ioutil.ReadDir(loc)
+	assert.Nil(t, err)
+	assert.Equal(t, 3, len(ff), "should keep 3 files only")
+	assert.Equal(t, "backup-site1-20171207.gz", ff[0].Name())
+	assert.Equal(t, "backup-site1-20171208.gz", ff[1].Name())
+	assert.Equal(t, "backup-site1-20171209.gz", ff[2].Name())
+}
diff --git a/app/rest/admin.go b/app/rest/admin.go
index 5eaa3e1e..ae31ddc6 100644
--- a/app/rest/admin.go
+++ b/app/rest/admin.go
@@ -36,7 +36,7 @@ func (a *admin) routes() chi.Router {
 	return router
 }
 
-// DELETE /comment/{id}?site=siteID&url=post-url
+// DELETE /comment/{id}?site=siteID&url=post-url - removes comment
 func (a *admin) deleteCommentCtrl(w http.ResponseWriter, r *http.Request) {
 
 	id := chi.URLParam(r, "id")
@@ -54,7 +54,7 @@ func (a *admin) deleteCommentCtrl(w http.ResponseWriter, r *http.Request) {
 	render.JSON(w, r, JSON{"id": id, "loc": locator})
 }
 
-// PUT /user/{userid}?site=side-id&block=1
+// PUT /user/{userid}?site=side-id&block=1 - block or unblock user
 func (a *admin) setBlockCtrl(w http.ResponseWriter, r *http.Request) {
 	userID := chi.URLParam(r, "userid")
 	siteID := r.URL.Query().Get("site")
@@ -68,7 +68,7 @@ func (a *admin) setBlockCtrl(w http.ResponseWriter, r *http.Request) {
 	render.JSON(w, r, JSON{"user_id": userID, "site_id": siteID, "block": blockStatus})
 }
 
-// PUT /pin/{id}?site=siteID&url=post-url&pin=1
+// PUT /pin/{id}?site=siteID&url=post-url&pin=1 - mark/unmark comment as a special
 func (a *admin) setPinCtrl(w http.ResponseWriter, r *http.Request) {
 	commentID := chi.URLParam(r, "id")
 	locator := store.Locator{SiteID: r.URL.Query().Get("site"), URL: r.URL.Query().Get("url")}
@@ -82,7 +82,7 @@ func (a *admin) setPinCtrl(w http.ResponseWriter, r *http.Request) {
 	render.JSON(w, r, JSON{"id": commentID, "loc": locator, "pin": pinStatus})
 }
 
-// GET /export?site=site-id?mode=file|stream
+// GET /export?site=site-id?mode=file|stream - exports all comments for siteID as json stream or file
 func (a *admin) exportCtrl(w http.ResponseWriter, r *http.Request) {
 	siteID := r.URL.Query().Get("site")
 	var writer io.Writer = w
@@ -105,6 +105,7 @@ func (a *admin) importCtrl(w http.ResponseWriter, r *http.Request) {
 	if err := a.importer.Import(r.Body, siteID); err != nil {
 		httpError(w, r, http.StatusBadRequest, err, "import failed")
 	}
+	a.respCache.Flush()
 }
 
 func (a *admin) checkBlocked(locator store.Locator, user store.User) bool {
diff --git a/app/rest/server.go b/app/rest/server.go
index 0e18ba7f..51a03a39 100644
--- a/app/rest/server.go
+++ b/app/rest/server.go
@@ -44,7 +44,8 @@ type Server struct {
 func (s *Server) Run() {
 	log.Print("[INFO] activate rest server")
 
-	applyDevMode := func(mode auth.Mode) (modes []auth.Mode) {
+	// add auth.Developer flag if dev mode is active
+	maybeDevMode := func(mode auth.Mode) (modes []auth.Mode) {
 		modes = append(modes, mode)
 		if s.DevMode {
 			modes = append(modes, auth.Developer)
@@ -57,7 +58,7 @@ func (s *Server) Run() {
 	router := chi.NewRouter()
 	router.Use(middleware.RealIP, Recoverer)
 	router.Use(middleware.Throttle(1000), middleware.Timeout(60*time.Second))
-	router.Use(auth.Auth(s.SessionStore, s.Admins, applyDevMode(auth.Anonymous)))
+	router.Use(auth.Auth(s.SessionStore, s.Admins, maybeDevMode(auth.Anonymous)))
 	router.Use(Limiter(10), AppInfo("remark", s.Version), Ping, Logger(LogAll))
 
 	// If you aren't using gorilla/mux, you need to wrap your handlers with context.ClearHandler
@@ -78,7 +79,7 @@ func (s *Server) Run() {
 		rapi.Get("/count", s.countCtrl)
 
 		// require auth
-		rapi.With(auth.Auth(s.SessionStore, s.Admins, applyDevMode(auth.Full))).Group(func(rauth chi.Router) {
+		rapi.With(auth.Auth(s.SessionStore, s.Admins, maybeDevMode(auth.Full))).Group(func(rauth chi.Router) {
 			rauth.Post("/comment", s.createCommentCtrl)
 			rauth.Get("/user", s.userInfoCtrl)
 			rauth.Put("/vote/{id}", s.voteCtrl)
@@ -95,26 +96,7 @@ func (s *Server) Run() {
 	log.Fatal(http.ListenAndServe(":8080", router))
 }
 
-func (s *Server) addFileServer(r chi.Router, path string, root http.FileSystem) {
-	fs := http.StripPrefix(path, http.FileServer(root))
-
-	if path != "/" && path[len(path)-1] != '/' {
-		r.Get(path, http.RedirectHandler(path+"/", 301).ServeHTTP)
-		path += "/"
-	}
-	path += "*"
-
-	r.Get(path, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		// don't show dirs, just serve files
-		if strings.HasSuffix(r.URL.Path, "/") {
-			http.NotFound(w, r)
-			return
-		}
-		fs.ServeHTTP(w, r)
-	}))
-}
-
-// POST /comment
+// POST /comment - adds comment, resets all immutable fields
 func (s *Server) createCommentCtrl(w http.ResponseWriter, r *http.Request) {
 
 	comment := store.Comment{}
@@ -151,7 +133,7 @@ func (s *Server) createCommentCtrl(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	s.respCache.Flush()
+	s.respCache.Flush() // reset all caches
 
 	render.Status(r, http.StatusAccepted)
 	render.JSON(w, r, JSON{"id": id, "loc": comment.Locator})
@@ -177,7 +159,8 @@ func (s *Server) deleteCommentCtrl(w http.ResponseWriter, r *http.Request) {
 	render.JSON(w, r, JSON{"id": id, "loc": locator})
 }
 
-// GET /find?site=siteID&url=post-url&format=tree&sort=-time
+// GET /find?site=siteID&url=post-url&format=[tree|plain]&sort=[+/-time|+/-score]
+// find comments for given post. Retruns in tree or plain formats, sorted
 func (s *Server) findCommentsCtrl(w http.ResponseWriter, r *http.Request) {
 	locator := store.Locator{SiteID: r.URL.Query().Get("site"), URL: r.URL.Query().Get("url")}
 	log.Printf("[DEBUG] get comments for %+v", locator)
@@ -204,7 +187,7 @@ func (s *Server) findCommentsCtrl(w http.ResponseWriter, r *http.Request) {
 	renderJSONWithHTML(w, r, comments)
 }
 
-// GET /last/{max}?site=siteID
+// GET /last/{max}?site=siteID - last comments for the siteID, across all posts, sorted by time
 func (s *Server) lastCommentsCtrl(w http.ResponseWriter, r *http.Request) {
 
 	max, err := strconv.Atoi(chi.URLParam(r, "max"))
@@ -230,7 +213,7 @@ func (s *Server) lastCommentsCtrl(w http.ResponseWriter, r *http.Request) {
 	renderJSONWithHTML(w, r, comments)
 }
 
-// GET /id/{id}?site=siteID&url=post-url
+// GET /id/{id}?site=siteID&url=post-url - gets a comment by id
 func (s *Server) commentByIDCtrl(w http.ResponseWriter, r *http.Request) {
 
 	id := chi.URLParam(r, "id")
@@ -248,7 +231,7 @@ func (s *Server) commentByIDCtrl(w http.ResponseWriter, r *http.Request) {
 	renderJSONWithHTML(w, r, comment)
 }
 
-// GET /comments?site=siteID&user=id
+// GET /comments?site=siteID&user=id - returns commens for given userID
 func (s *Server) findUserCommentsCtrl(w http.ResponseWriter, r *http.Request) {
 
 	userID := r.URL.Query().Get("user")
@@ -273,7 +256,7 @@ func (s *Server) findUserCommentsCtrl(w http.ResponseWriter, r *http.Request) {
 	renderJSONWithHTML(w, r, comments)
 }
 
-// GET /user
+// GET /user - returns user info
 func (s *Server) userInfoCtrl(w http.ResponseWriter, r *http.Request) {
 	user, err := auth.GetUserInfo(r)
 	if err != nil {
@@ -283,7 +266,7 @@ func (s *Server) userInfoCtrl(w http.ResponseWriter, r *http.Request) {
 	render.JSON(w, r, user)
 }
 
-// GET /count?site=siteID&url=post-url
+// GET /count?site=siteID&url=post-url - get number of comments for given post
 func (s *Server) countCtrl(w http.ResponseWriter, r *http.Request) {
 	locator := store.Locator{SiteID: r.URL.Query().Get("site"), URL: r.URL.Query().Get("url")}
 	count, err := s.DataService.Count(locator)
@@ -294,7 +277,7 @@ func (s *Server) countCtrl(w http.ResponseWriter, r *http.Request) {
 	render.JSON(w, r, JSON{"count": count, "loc": locator})
 }
 
-// PUT /vote/{id}?site=siteID&url=post-url&vote=1
+// PUT /vote/{id}?site=siteID&url=post-url&vote=1 - vote for/against comment
 func (s *Server) voteCtrl(w http.ResponseWriter, r *http.Request) {
 
 	user, err := auth.GetUserInfo(r)
@@ -338,3 +321,22 @@ func renderJSONWithHTML(w http.ResponseWriter, r *http.Request, v interface{}) {
 	}
 	_, _ = w.Write(buf.Bytes())
 }
+
+func (s *Server) addFileServer(r chi.Router, path string, root http.FileSystem) {
+	fs := http.StripPrefix(path, http.FileServer(root))
+
+	if path != "/" && path[len(path)-1] != '/' {
+		r.Get(path, http.RedirectHandler(path+"/", 301).ServeHTTP)
+		path += "/"
+	}
+	path += "*"
+
+	r.Get(path, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// don't show dirs, just serve files
+		if strings.HasSuffix(r.URL.Path, "/") {
+			http.NotFound(w, r)
+			return
+		}
+		fs.ServeHTTP(w, r)
+	}))
+}
diff --git a/app/store/bolt.go b/app/store/bolt.go
index eea59447..c08fc84e 100644
--- a/app/store/bolt.go
+++ b/app/store/bolt.go
@@ -86,8 +86,8 @@ func (b *BoltDB) Create(comment Comment) (string, error) {
 			return errors.Wrap(jerr, "can't marshal comment")
 		}
 
-		if err := bucket.Put([]byte(comment.ID), jdata); err != nil {
-			return errors.Wrapf(err, "failed to put key %s", comment.ID)
+		if e = bucket.Put([]byte(comment.ID), jdata); err != nil {
+			return errors.Wrapf(e, "failed to put key %s", comment.ID)
 		}
 
 		// add reference to comment to "last" bucket