diff --git a/src/lib/snark_keys_header/dune b/src/lib/snark_keys_header/dune
new file mode 100644
index 00000000000..65fd9e4df31
--- /dev/null
+++ b/src/lib/snark_keys_header/dune
@@ -0,0 +1,6 @@
+(library
+ (name snark_keys_header)
+ (public_name snark_keys_header)
+ (libraries core_kernel runtime_config unsigned_extended)
+ (instrumentation (backend bisect_ppx))
+ (preprocess (pps ppx_version ppx_deriving_yojson)))
diff --git a/src/lib/snark_keys_header/snark_keys_header.ml b/src/lib/snark_keys_header/snark_keys_header.ml
new file mode 100644
index 00000000000..3f8fd6bbee2
--- /dev/null
+++ b/src/lib/snark_keys_header/snark_keys_header.ml
@@ -0,0 +1,104 @@
+open Core_kernel
+
+(** The string that preceeds the JSON header, to identify the file kind before
+    attempting to parse it.
+*)
+let header_string = "MINA_SNARK_KEYS\n"
+
+module Kind = struct
+  (** The 'kind' of data in the file.
+    For example, a step proving key for the base transaction snark may have the
+    kind:
+{[
+  {type_= "step_proving_key"; identifier= "transaction_snark_base"}
+|}
+  *)
+  type t =
+    { type_: string [@key "type"]
+          (** Identifies the type of data that the file contains *)
+    ; identifier: string
+          (** Identifies the specific purpose of the file's data, in a
+            human-readable format
+        *)
+    }
+  [@@deriving yojson]
+end
+
+module Constraint_constants = struct
+  module Transaction_capacity = struct
+    (** Transaction pool capacity *)
+    type t = Log_2 of int | Txns_per_second_x10 of int
+
+    let to_yojson t : Yojson.Safe.t =
+      match t with
+      | Log_2 i ->
+          `Assoc [("two_to_the", `Int i)]
+      | Txns_per_second_x10 i ->
+          `Assoc [("txns_per_second_x10", `Int i)]
+
+    let of_yojson (json : Yojson.Safe.t) =
+      match json with
+      | `Assoc [("two_to_the", `Int i)] ->
+          Ok (Log_2 i)
+      | `Assoc [("txns_per_second_x10", `Int i)] ->
+          Ok (Txns_per_second_x10 i)
+      | `Assoc _ ->
+          Error
+            "Snark_keys_header.Constraint_constants.Transaction_capacity.of_yojson: \
+             Expected a JSON object containing the field 'two_to_the' or \
+             'txns_per_second_x10'"
+      | _ ->
+          Error
+            "Snark_keys_header.Constraint_constants.Transaction_capacity.of_yojson: \
+             Expected a JSON object"
+  end
+
+  module Fork_config = struct
+    (** Fork data *)
+    type t = Runtime_config.Fork_config.t =
+      {previous_state_hash: string; previous_length: int}
+    [@@deriving yojson]
+
+    let opt_to_yojson t : Yojson.Safe.t =
+      match t with Some t -> to_yojson t | None -> `Assoc []
+
+    let opt_of_yojson (json : Yojson.Safe.t) =
+      match json with
+      | `Assoc [] ->
+          Ok None
+      | _ ->
+          Result.map (of_yojson json) ~f:(fun t -> Some t)
+  end
+
+  (** The constants used in the constraint system.  *)
+  type t =
+    { sub_windows_per_window: int
+    ; ledger_depth: int
+    ; work_delay: int
+    ; block_window_duration_ms: int
+    ; transaction_capacity: Transaction_capacity.t
+    ; coinbase_amount: Unsigned_extended.UInt64.t
+    ; supercharged_coinbase_factor: int
+    ; account_creation_fee: Unsigned_extended.UInt64.t
+    ; fork:
+        (Fork_config.t option[@to_yojson Fork_config.opt_to_yojson]
+                             [@of_yojson Fork_config.opt_of_yojson]) }
+  [@@deriving yojson]
+end
+
+module Commits = struct
+  (** Commit identifiers *)
+  type t = {mina: string; marlin: string} [@@deriving yojson]
+end
+
+(** Header contents *)
+type t =
+  { header_version: int
+  ; kind: Kind.t
+  ; constraint_constants: Constraint_constants.t
+  ; commits: Commits.t
+  ; length: int
+  ; commit_date: string
+  ; constraint_system_hash: string
+  ; identifying_hash: string }
+[@@deriving yojson]
diff --git a/src/snark_keys_header.opam b/src/snark_keys_header.opam
new file mode 100644
index 00000000000..fa5836a0180
--- /dev/null
+++ b/src/snark_keys_header.opam
@@ -0,0 +1,24 @@
+opam-version: "2"
+name: "snark_keys_header"
+maintainer: "opensource@o1labs.org"
+authors: ["O(1) Labs, LLC <opensource@o1labs.org>"]
+homepage: "https://github.com/CodaProtocol/coda"
+bug-reports: "https://github.com/CodaProtocol/coda/issues"
+dev-repo: "https://github.com/CodaProtocol/coda.git"
+license: "Apache"
+build: [
+  ["dune" "build" "-p" name "-j" jobs]
+]
+depends: [
+  "core_kernel"
+  "dune"                {build & >= "2.0"}
+  "ppx_version"
+  "ppx_deriving_yojson"
+  "unsigned_extended"
+]
+synopsis: "Headers for mina snark keys"
+description: "
+Headers for mina snark key files and related files, exposing relevant data in a
+JSON-formatted object
+"
+