diff --git a/appview/repo/blob.go b/appview/repo/blob.go
--- a/appview/repo/blob.go
+++ b/appview/repo/blob.go
@@ -236,7 +236,7 @@
 		ext := strings.ToLower(filepath.Ext(resp.Path))
 
 		switch ext {
-		case ".jpg", ".jpeg", ".png", ".gif", ".webp":
+		case ".jpg", ".jpeg", ".png", ".gif", ".webp", ".avif", ".jxl", ".heic", ".heif":
 			view.ContentType = models.BlobContentTypeImage
 			view.HasRawView = true
 			view.HasRenderedView = true
diff --git a/camo/src/mimetypes.json b/camo/src/mimetypes.json
--- a/camo/src/mimetypes.json
+++ b/camo/src/mimetypes.json
@@ -1,10 +1,13 @@
 [
+  "image/avif",
   "image/bmp",
   "image/cgm",
   "image/g3fax",
   "image/gif",
+  "image/heif",
   "image/ief",
   "image/jp2",
+  "image/jxl",
   "image/jpeg",
   "image/jpg",
   "image/pict",
diff --git a/knotserver/xrpc/repo_blob.go b/knotserver/xrpc/repo_blob.go
--- a/knotserver/xrpc/repo_blob.go
+++ b/knotserver/xrpc/repo_blob.go
@@ -74,8 +74,16 @@
 
 	mimeType := http.DetectContentType(contents)
 
-	if filepath.Ext(treePath) == ".svg" {
+	// override MIME types for formats that http.DetectContentType does not recognize
+	switch filepath.Ext(treePath) {
+	case ".svg":
 		mimeType = "image/svg+xml"
+	case ".avif":
+		mimeType = "image/avif"
+	case ".jxl":
+		mimeType = "image/jxl"
+	case ".heic", ".heif":
+		mimeType = "image/heif"
 	}
 
 	if raw {