diff --git a/cpdfbookmarks.ml b/cpdfbookmarks.ml
index 1d6cef8..9039775 100644
--- a/cpdfbookmarks.ml
+++ b/cpdfbookmarks.ml
@@ -262,7 +262,10 @@ let list_bookmarks ~json encoding range pdf output =
                    (output_string_of_target pdf fastrefnums mark.Pdfmarks.target)))
             inrange
 
-(* o is the stamp, u is the main pdf page *)
+let get_bookmarks_json pdf =
+  let o, br = Pdfio.input_output_of_bytes (20 * 1024) in
+    list_bookmarks ~json:true Cpdfmetadata.UTF8 (ilist 1 (Pdfpage.endpage pdf)) pdf o;
+    Pdfio.extract_bytes_from_input_output o br
 
 (* Split at bookmarks *)
 
diff --git a/cpdfbookmarks.mli b/cpdfbookmarks.mli
index 79723ba..ef77870 100644
--- a/cpdfbookmarks.mli
+++ b/cpdfbookmarks.mli
@@ -14,6 +14,9 @@ output in the format specified in cpdfmanual.pdf. In the new JSON format if
 chosen. *)
 val list_bookmarks : json:bool -> Cpdfmetadata.encoding -> int list -> Pdf.t -> Pdfio.output -> unit
 
+(** Get bookmarks in JSON format. *)
+val get_bookmarks_json : Pdf.t -> Pdfio.bytes
+
 (** [name_of_spec encoding marks pdf splitlevel spec n filename startpage
     endpage] expands a bookmark specifiation filename. *)
 val name_of_spec : Cpdfmetadata.encoding ->