diff --git a/src/proto_alpha/lib_baking/client_baking_forge.ml b/src/proto_alpha/lib_baking/client_baking_forge.ml
index 489d45fc8..d5072a395 100644
--- a/src/proto_alpha/lib_baking/client_baking_forge.ml
+++ b/src/proto_alpha/lib_baking/client_baking_forge.ml
@@ -156,7 +156,8 @@ let forge_block cctxt ?(chain = `Main) block
         return (priority, Some time)
       end
     | `Auto (src_pkh, max_priority, free_baking) ->
-        Alpha_services.Helpers.next_level cctxt (chain, block) >>=? fun { level } ->
+        Alpha_services.Helpers.level
+          cctxt ~offset:1l (chain, block)>>=? fun { level } ->
         Alpha_services.Delegate.Baking_rights.get cctxt
           ?max_priority
           ~levels:[level]
@@ -392,7 +393,7 @@ let compute_timeout { future_slots } =
 
 let get_unrevealed_nonces
     (cctxt : #Proto_alpha.full) ?(force = false) ?(chain = `Main) block =
-  Alpha_services.Helpers.next_level cctxt (chain, block) >>=? fun level ->
+  Alpha_services.Helpers.level cctxt ~offset:1l (chain, block) >>=? fun level ->
   let cur_cycle = level.cycle in
   match Cycle.pred cur_cycle with
   | None -> return []
@@ -491,7 +492,7 @@ let bake (cctxt : #Proto_alpha.full) state =
     (fun (timestamp, (bi, priority, delegate)) ->
        let chain = `Hash bi.Client_baking_blocks.chain_id in
        let block = `Hash (bi.hash, 0) in
-       Alpha_services.Helpers.next_level cctxt (chain, block) >>=? fun next_level ->
+       Alpha_services.Helpers.level cctxt ~offset:1l (chain, block) >>=? fun next_level ->
        let timestamp =
          if Block_hash.equal bi.Client_baking_blocks.hash state.genesis then
            Time.now ()
diff --git a/src/proto_alpha/lib_baking/client_baking_lib.ml b/src/proto_alpha/lib_baking/client_baking_lib.ml
index be1413a47..358c0ee90 100644
--- a/src/proto_alpha/lib_baking/client_baking_lib.ml
+++ b/src/proto_alpha/lib_baking/client_baking_lib.ml
@@ -21,7 +21,7 @@ let bake_block (cctxt : #Proto_alpha.full)
         return src_sk
     | Some sk -> return sk
   end >>=? fun src_sk ->
-  Alpha_services.Helpers.next_level cctxt (chain, block) >>=? fun level ->
+  Alpha_services.Helpers.level cctxt ~offset:1l (chain, block) >>=? fun level ->
   let seed_nonce, seed_nonce_hash =
     if level.expected_commitment then
       let seed_nonce = Client_baking_forge.generate_seed_nonce () in
diff --git a/src/proto_alpha/lib_baking/test/proto_alpha_helpers.ml b/src/proto_alpha/lib_baking/test/proto_alpha_helpers.ml
index d9de9fd1d..131ea4009 100644
--- a/src/proto_alpha/lib_baking/test/proto_alpha_helpers.ml
+++ b/src/proto_alpha/lib_baking/test/proto_alpha_helpers.ml
@@ -342,8 +342,8 @@ module Protocol = struct
 
   let proposals ?(block = `Head 0) ~src:({ pkh; sk } : Account.t) proposals =
     Block_services.hash !rpc_ctxt ~block () >>=? fun hash ->
-    Alpha_services.Helpers.next_level
-      !rpc_ctxt (`Main, block) >>=? fun next_level ->
+    Alpha_services.Helpers.level
+      !rpc_ctxt ~offset:1l (`Main, block) >>=? fun next_level ->
     let shell = { Tezos_base.Operation.branch = hash } in
     let contents =
       Amendment_operation
@@ -354,8 +354,8 @@ module Protocol = struct
 
   let ballot ?(block = `Head 0) ~src:({ pkh; sk } : Account.t) ~proposal ballot =
     Block_services.hash !rpc_ctxt ~block () >>=? fun hash ->
-    Alpha_services.Helpers.next_level
-      !rpc_ctxt (`Main, block) >>=? fun next_level ->
+    Alpha_services.Helpers.level
+      !rpc_ctxt ~offset:1l (`Main, block) >>=? fun next_level ->
     let shell = { Tezos_base.Operation.branch = hash } in
     let contents =
       Amendment_operation
@@ -516,7 +516,7 @@ module Baking = struct
 
   let bake block (contract: Account.t) operations =
     let ctxt = (new wrap_full (no_write_context ~block !rpc_config)) in
-    Alpha_services.Helpers.next_level ctxt (`Main, block) >>=? fun level ->
+    Alpha_services.Helpers.level ctxt ~offset:1l (`Main, block) >>=? fun level ->
     let seed_nonce_hash =
       if level.Level.expected_commitment then
         let seed_nonce =
diff --git a/src/proto_alpha/lib_protocol/src/helpers_services.ml b/src/proto_alpha/lib_protocol/src/helpers_services.ml
index 1eed38a98..0b3d70d04 100644
--- a/src/proto_alpha/lib_protocol/src/helpers_services.ml
+++ b/src/proto_alpha/lib_protocol/src/helpers_services.ml
@@ -40,19 +40,44 @@ module S = struct
 
   let custom_root = RPC_path.(open_root / "helpers")
 
-  let next_level =
-    RPC_service.post_service
-      ~description: "Detailled level information for the next block"
-      ~query: RPC_query.empty
-      ~input: empty
+  type level_query = {
+    offset: int32 ;
+  }
+  let level_query : level_query RPC_query.t =
+    let open RPC_query in
+    query (fun offset -> { offset })
+    |+ field "offset" RPC_arg.int32 0l (fun t -> t.offset)
+    |> seal
+
+  let level =
+    RPC_service.get_service
+      ~description: "..."
+      ~query: level_query
       ~output: Level.encoding
-      RPC_path.(custom_root / "next_level")
+      RPC_path.(custom_root / "level")
+
+  let levels =
+    RPC_service.get_service
+      ~description: "Levels of a cycle"
+      ~query: RPC_query.empty
+      ~output: (obj2
+                  (req "first" Raw_level.encoding)
+                  (req "last" Raw_level.encoding))
+      RPC_path.(custom_root / "levels_in_cycle" /: Cycle.arg)
+
+  type minimal_timestamp_query = {
+    priority: int ;
+  }
+  let minimal_timestamp_query : minimal_timestamp_query RPC_query.t =
+    let open RPC_query in
+    query (fun priority -> { priority })
+    |+ field "priority" RPC_arg.int 0 (fun t -> t.priority)
+    |> seal
 
   let minimal_timestamp =
-    RPC_service.post_service
+    RPC_service.get_service
       ~description: "Minimal timestamp for the next block."
-      ~query: RPC_query.empty
-      ~input: (obj1 (opt "priority" int31))
+      ~query: minimal_timestamp_query
       ~output: (obj1 (req "timestamp" Timestamp.encoding))
       RPC_path.(custom_root / "minimal_timestamp")
 
@@ -143,24 +168,6 @@ module S = struct
       ~query: RPC_query.empty
       RPC_path.(custom_root / "hash_data")
 
-  let level =
-    RPC_service.post_service
-      ~description: "..."
-      ~query: RPC_query.empty
-      ~input: (obj1 (opt "offset" int32))
-      ~output: Level.encoding
-      RPC_path.(custom_root / "level" /: Raw_level.arg)
-
-  let levels =
-    RPC_service.post_service
-      ~description: "Levels of a cycle"
-      ~query: RPC_query.empty
-      ~input: empty
-      ~output:  (obj2
-                   (req "first" Raw_level.encoding)
-                   (req "last" Raw_level.encoding))
-      RPC_path.(custom_root / "levels" /: Cycle.arg)
-
 end
 
 module I = struct
@@ -181,13 +188,19 @@ end
 
 let () =
   let open Services_registration in
-  register0 S.next_level begin fun ctxt () () ->
-    return (Level.succ ctxt (Level.current ctxt))
+  register0 S.level begin fun ctxt q () ->
+    let level = Level.current ctxt in
+    return (Level.from_raw ctxt ~offset:q.offset level.level)
   end ;
-  register0 S.minimal_timestamp begin fun ctxt () slot ->
+  register1 S.levels begin fun ctxt cycle () () ->
+    let levels = Level.levels_in_cycle ctxt cycle in
+    let first = List.hd (List.rev levels) in
+    let last = List.hd levels in
+    return (first.level, last.level)
+  end ;
+  register0 S.minimal_timestamp begin fun ctxt q () ->
     let timestamp = Alpha_context.Timestamp.current ctxt in
-    let slot = match slot with None -> 0 | Some p -> p in
-    Baking.minimal_time ctxt slot timestamp
+    Baking.minimal_time ctxt q.priority timestamp
   end ;
   register0 S.apply_operation I.apply_operation ;
   register0 S.run_code begin fun ctxt ()
@@ -243,22 +256,16 @@ let () =
     parse_data ctxt typ (Micheline.root expr) >>=? fun (data, ctxt) ->
     Script_ir_translator.hash_data ctxt typ data >>=? fun (hash, ctxt) ->
     return (hash, Gas.level ctxt)
-  end ;
-  register1 S.level begin fun ctxt raw () offset ->
-    return (Level.from_raw ctxt ?offset raw)
-  end ;
-  register1 S.levels begin fun ctxt cycle () () ->
-    let levels = Level.levels_in_cycle ctxt cycle in
-    let first = List.hd (List.rev levels) in
-    let last = List.hd levels in
-    return (first.level, last.level)
   end
 
-let next_level ctxt block =
-  RPC_context.make_call0 S.next_level ctxt block () ()
+let level ctxt ?(offset = 0l) block =
+  RPC_context.make_call0 S.level ctxt block { offset } ()
 
-let minimal_time ctxt ?priority block =
-  RPC_context.make_call0 S.minimal_timestamp ctxt block () priority
+let levels ctxt block cycle =
+  RPC_context.make_call1 S.levels ctxt block cycle () ()
+
+let minimal_time ctxt ?(priority = 0) block =
+  RPC_context.make_call0 S.minimal_timestamp ctxt block { priority } ()
 
 let run_code ctxt block code (storage, input, amount, contract) =
   RPC_context.make_call0 S.run_code ctxt
@@ -281,12 +288,6 @@ let typecheck_data ctxt block =
 let hash_data ctxt block =
   RPC_context.make_call0 S.hash_data ctxt block ()
 
-let level ctxt block ?offset lvl =
-  RPC_context.make_call1 S.level ctxt block lvl () offset
-
-let levels ctxt block cycle =
-  RPC_context.make_call1 S.levels ctxt block cycle () ()
-
 module Forge = struct
 
   module S = struct
diff --git a/src/proto_alpha/lib_protocol/src/helpers_services.mli b/src/proto_alpha/lib_protocol/src/helpers_services.mli
index c28e869c5..a1405861a 100644
--- a/src/proto_alpha/lib_protocol/src/helpers_services.mli
+++ b/src/proto_alpha/lib_protocol/src/helpers_services.mli
@@ -13,10 +13,13 @@ type error +=
   | Cannot_parse_operation (* `Branch *)
   | Cant_parse_block_header
 
-val next_level:
-  'a #RPC_context.simple -> 'a -> Level.t shell_tzresult Lwt.t
-(** [next_level cctxt blk] returns the (protocol view of the) level
-    of the successor of [blk]. *)
+val level:
+  'a #RPC_context.simple ->
+  ?offset:int32 -> 'a -> Level.t shell_tzresult Lwt.t
+
+val levels:
+  'a #RPC_context.simple ->
+  'a -> Cycle.t -> (Raw_level.t * Raw_level.t) shell_tzresult Lwt.t
 
 val minimal_time:
   'a #RPC_context.simple ->
@@ -60,15 +63,6 @@ val hash_data:
   'a #RPC_context.simple ->
   'a -> Script.expr * Script.expr * Z.t option -> (string * Gas.t) shell_tzresult Lwt.t
 
-val level:
-  'a #RPC_context.simple ->
-  'a -> ?offset:int32 -> Raw_level.t -> Level.t shell_tzresult Lwt.t
-
-val levels:
-  'a #RPC_context.simple ->
-  'a -> Cycle.t -> (Raw_level.t * Raw_level.t) shell_tzresult Lwt.t
-
-
 module Forge : sig
 
   module Manager : sig
diff --git a/src/proto_alpha/lib_protocol/test/helpers/block.ml b/src/proto_alpha/lib_protocol/test/helpers/block.ml
index de083142b..e88ee1eac 100644
--- a/src/proto_alpha/lib_protocol/test/helpers/block.ml
+++ b/src/proto_alpha/lib_protocol/test/helpers/block.ml
@@ -149,7 +149,7 @@ module Forge = struct
       | Error _ -> assert false
     end >>=? fun fitness ->
     begin
-      Alpha_services.Helpers.next_level (rpc_ctxt) pred >>|? function
+      Alpha_services.Helpers.level ~offset:1l (rpc_ctxt) pred >>|? function
       | { expected_commitment = true } -> Some (fst (Proto_Nonce.generate ()))
       | { expected_commitment = false } -> None
     end >>=? fun seed_nonce_hash ->