diff --git a/pkgs/development/ocaml-modules/cmon/default.nix b/pkgs/development/ocaml-modules/cmon/default.nix
new file mode 100644
index 000000000000..3edc0bb5e226
--- /dev/null
+++ b/pkgs/development/ocaml-modules/cmon/default.nix
@@ -0,0 +1,30 @@
+{
+  lib,
+  fetchurl,
+  buildDunePackage,
+  grenier,
+  pprint,
+}:
+
+buildDunePackage (finalAttrs: {
+  pname = "cmon";
+  version = "0.2";
+
+  src = fetchurl {
+    url = "https://github.com/let-def/cmon/releases/download/v${finalAttrs.version}/cmon-${finalAttrs.version}.tbz";
+    hash = "sha256-lJi5NV27YqyDgUx1i4vBj/buzyzdWJSrSceGGs82grg=";
+  };
+
+  propagatedBuildInputs = [
+    grenier
+    pprint
+  ];
+
+  doCheck = true;
+
+  meta = {
+    description = "A library for printing OCaml values with sharing";
+    license = lib.licenses.mit;
+    homepage = "https://github.com/let-def/cmon";
+  };
+})
diff --git a/pkgs/development/ocaml-modules/grenier/default.nix b/pkgs/development/ocaml-modules/grenier/default.nix
new file mode 100644
index 000000000000..88f50619d7c6
--- /dev/null
+++ b/pkgs/development/ocaml-modules/grenier/default.nix
@@ -0,0 +1,22 @@
+{
+  lib,
+  fetchurl,
+  buildDunePackage,
+}:
+
+buildDunePackage (finalAttrs: {
+  pname = "grenier";
+  version = "0.16";
+  src = fetchurl {
+    url = "https://github.com/let-def/grenier/releases/download/v${finalAttrs.version}/grenier-${finalAttrs.version}.tbz";
+    hash = "sha256-j9Iqv59FicIGAIZU+p7rsc9KWHN+uzQTjGcJUg82t18=";
+  };
+
+  doCheck = true;
+
+  meta = {
+    description = "A collection of various algorithms in OCaml";
+    license = lib.licenses.isc;
+    homepage = "https://github.com/let-def/grenier";
+  };
+})
diff --git a/pkgs/development/ocaml-modules/lrgrep/default.nix b/pkgs/development/ocaml-modules/lrgrep/default.nix
new file mode 100644
index 000000000000..7a51a78d623f
--- /dev/null
+++ b/pkgs/development/ocaml-modules/lrgrep/default.nix
@@ -0,0 +1,37 @@
+{
+  lib,
+  fetchurl,
+  buildDunePackage,
+  menhir,
+  cmon,
+  menhirLib,
+  menhirSdk,
+}:
+
+buildDunePackage (finalAttrs: {
+  pname = "lrgrep";
+  version = "0.9";
+
+  minimalOCamlVersion = "4.14";
+
+  src = fetchurl {
+    url = "https://github.com/let-def/lrgrep/releases/download/v${finalAttrs.version}/lrgrep-${finalAttrs.version}.tbz";
+    hash = "sha256-5T3hLkxcvmvKAGQ1kyZrT5+i4/ahOBle7/ekMp9cHHU=";
+  };
+
+  nativeBuildInputs = [ menhir ];
+
+  propagatedBuildInputs = [
+    cmon
+    menhirLib
+    menhirSdk
+  ];
+
+  doCheck = true;
+
+  meta = {
+    license = lib.licenses.isc;
+    description = "Detailed error messages for Menhir-generated parsers";
+    homepage = "https://github.com/let-def/lrgrep";
+  };
+})
diff --git a/pkgs/top-level/ocaml-packages.nix b/pkgs/top-level/ocaml-packages.nix
index 9191c658132e..7e85b77a462a 100644
--- a/pkgs/top-level/ocaml-packages.nix
+++ b/pkgs/top-level/ocaml-packages.nix
@@ -275,6 +275,8 @@ let
 
         cmdliner_1 = cmdliner.override { version = "1.3.0"; };
 
+        cmon = callPackage ../development/ocaml-modules/cmon { };
+
         cohttp = callPackage ../development/ocaml-modules/cohttp { };
 
         cohttp_5_3 = cohttp.overrideAttrs (_: {
@@ -800,6 +802,8 @@ let
 
         graphql_ppx = callPackage ../development/ocaml-modules/graphql_ppx { };
 
+        grenier = callPackage ../development/ocaml-modules/grenier { };
+
         gsl = callPackage ../development/ocaml-modules/gsl {
           inherit (pkgs) gsl;
         };
@@ -1163,6 +1167,8 @@ let
 
         lreplay = callPackage ../development/ocaml-modules/lreplay { };
 
+        lrgrep = callPackage ../development/ocaml-modules/lrgrep { };
+
         lru = callPackage ../development/ocaml-modules/lru { };
 
         lsp = callPackage ../development/ocaml-modules/ocaml-lsp/lsp.nix { };