diff --git a/json.ml b/json.ml
new file mode 100644
index 00000000..76c243c1
--- /dev/null
+++ b/json.ml
@@ -0,0 +1,171 @@
+(*
+Copyright (c) 2013, Simon Cruanes
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+Redistributions of source code must retain the above copyright notice, this
+list of conditions and the following disclaimer.  Redistributions in binary
+form must reproduce the above copyright notice, this list of conditions and the
+following disclaimer in the documentation and/or other materials provided with
+the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*)
+
+(** {1 Very simple JSON parser/printer} *)
+
+type t =
+  | Int of int
+  | Float of float
+  | String of string
+  | Null
+  | Bool of bool
+  | List of t list
+  | Object of (string * t) list
+
+(** {2 Print/parse} *)
+
+let lex =
+  Genlex.make_lexer ["{"; "}"; ":"; ","; "["; "]"; "true"; "false"; "null"]
+
+exception EOF
+
+let parse chars =
+  let tokens = lex chars in
+  let open Stream in
+  let rec next () =
+    match peek tokens with
+    | None -> raise EOF (* end stream *)
+    | Some (Genlex.Kwd "{") ->
+      junk tokens;
+      let args = read_pairs [] in
+      (match peek tokens with
+        | Some (Genlex.Kwd "}") ->
+          junk tokens; Object args
+        | _ -> raise (Stream.Error "expected '}'"))
+    | Some (Genlex.Kwd "[") ->
+      junk tokens;
+      let args = read_list [] in
+      (match peek tokens with
+        | Some (Genlex.Kwd "]") ->
+          junk tokens; List args
+        | _ -> raise (Stream.Error "expected ']'"))
+    | Some (Genlex.Int i) -> junk tokens; Int i
+    | Some (Genlex.Float f) -> junk tokens; Float f
+    | Some (Genlex.Kwd "true") -> junk tokens; Bool true
+    | Some (Genlex.Kwd "false") -> junk tokens; Bool false
+    | Some (Genlex.Kwd "null") -> junk tokens; Null
+    | _ -> raise (Stream.Error "expected JSON value")
+  and read_list acc =
+    match peek tokens with
+    | Some (Genlex.Kwd "]") -> List.rev acc  (* yield *)
+    | _ ->
+      let t = next () in
+      (match peek tokens with
+        | Some (Genlex.Kwd ",") ->
+          junk tokens;
+          read_list (t::acc)  (* next *)
+        | Some (Genlex.Kwd "]") ->
+          read_list (t::acc)  (* next *)
+        | Some (Genlex.Kwd "]") -> List.rev acc  (* yield *)
+        | _ -> raise (Stream.Error "expected ','"))
+  and read_pairs acc =
+    match peek tokens with
+    | Some (Genlex.Kwd "}") -> List.rev acc  (* yield *)
+    | _ ->
+      let k, v = pair () in
+      (match peek tokens with
+        | Some (Genlex.Kwd ",") ->
+          junk tokens;
+          read_pairs ((k,v)::acc)  (* next *)
+        | Some (Genlex.Kwd "}") ->
+          read_pairs ((k,v)::acc)  (* next *)
+        | _ -> raise (Stream.Error "expected ','"))
+  and pair () = 
+    match Stream.npeek 2 tokens with
+    | [Genlex.String k; Genlex.Kwd ":"] ->
+      junk tokens; junk tokens;
+      let v = next () in
+      k, v
+    | _ -> raise (Stream.Error "expected pair")
+  in
+  Stream.from
+    (fun _ ->
+      try Some (next ())
+      with EOF -> None)
+
+let parse_one chars =
+  Stream.peek (parse chars)
+
+let rec output oc t =
+  match t with
+  | Null -> output_string oc "null"
+  | Bool true -> output_string oc "true"
+  | Bool false -> output_string oc "false"
+  | Int i -> Printf.fprintf oc "%d" i
+  | Float f -> Printf.fprintf oc "%f" f
+  | String s -> Printf.fprintf oc "\"%s\"" (String.escaped s)
+  | List l ->
+    output_string oc "[";
+    List.iteri
+      (fun i t ->
+        (if i > 0 then output_string oc ", ");
+        output oc t)
+      l;
+    output_string oc "]"
+  | Object pairs ->
+    output_string oc "{";
+    List.iteri
+      (fun i (k,v) ->
+        (if i > 0 then output_string oc ", ");
+        Printf.fprintf oc "\"%s\": " k;
+        output oc v)
+      pairs;
+    output_string oc "}"
+
+let rec pp fmt t =
+  match t with
+  | Null -> Format.pp_print_string fmt "null"
+  | Bool true -> Format.pp_print_string fmt "true"
+  | Bool false -> Format.pp_print_string fmt "false"
+  | Int i -> Format.fprintf fmt "%d" i
+  | Float f -> Format.fprintf fmt "%f" f
+  | String s -> Format.fprintf fmt "\"%s\"" (String.escaped s)
+  | List l ->
+    Format.pp_print_string fmt "[";
+    List.iteri
+      (fun i t  ->
+        (if i > 0 then Format.pp_print_string fmt ", ");
+        pp fmt t)
+      l;
+    Format.pp_print_string fmt "]"
+  | Object pairs ->
+    Format.pp_print_string fmt "{";
+    List.iteri
+      (fun i (k,v) ->
+        (if i > 0 then Format.pp_print_string fmt ", ");
+        Format.fprintf fmt "\"%s\": " k;
+        pp fmt v)
+      pairs;
+    Format.pp_print_string fmt "}"
+
+let to_string t =
+  let buf = Buffer.create 16 in
+  Format.bprintf buf "%a@?" pp t;
+  Buffer.contents buf
+
+(** {2 Utils *)
+
+exception TypeError of string * t
+
diff --git a/json.mli b/json.mli
new file mode 100644
index 00000000..3c112d77
--- /dev/null
+++ b/json.mli
@@ -0,0 +1,62 @@
+(*
+Copyright (c) 2013, Simon Cruanes
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+Redistributions of source code must retain the above copyright notice, this
+list of conditions and the following disclaimer.  Redistributions in binary
+form must reproduce the above copyright notice, this list of conditions and the
+following disclaimer in the documentation and/or other materials provided with
+the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*)
+
+(** {1 Very simple JSON parser/printer} *)
+
+type t =
+  | Int of int
+  | Float of float
+  | String of string
+  | Null
+  | Bool of bool
+  | List of t list
+  | Object of (string * t) list
+
+(** {2 Print/parse} *)
+
+val parse : char Stream.t -> t Stream.t
+
+val parse_one : char Stream.t -> t option
+
+val output : out_channel -> t -> unit
+
+val pp : Format.formatter -> t -> unit
+
+val to_string : t -> string
+
+(** {2 Utils *)
+
+exception TypeError of string * t
+
+(*
+val to_int : t -> int
+val to_float : t -> float
+val to_string : t -> string
+val to_bool : t -> bool
+val to_null : t -> unit
+val to_list : t -> t list
+val to_object : t -> (string * t) list
+
+*)