diff --git a/maintainers/maintainer-list.nix b/maintainers/maintainer-list.nix
index 22c5f4804ab2..dc0679f0cccc 100644
--- a/maintainers/maintainer-list.nix
+++ b/maintainers/maintainer-list.nix
@@ -24378,6 +24378,13 @@
     githubId = 20464732;
     name = "Willi Butz";
   };
+  willow_ch = {
+    email = "nix@w.wolo.dev";
+    github = "spaghetus";
+    githubId = 28763739;
+    name = "Willow Carlson-Huber";
+    keys = [ { fingerprint = "FE21E0981CDFD50ADD086423C21A693BA4693A60"; } ];
+  };
   willswats = {
     email = "williamstuwatson@gmail.com";
     github = "willswats";
diff --git a/pkgs/by-name/ca/caper/package.nix b/pkgs/by-name/ca/caper/package.nix
new file mode 100644
index 000000000000..f7dc73b829de
--- /dev/null
+++ b/pkgs/by-name/ca/caper/package.nix
@@ -0,0 +1,64 @@
+{
+  stdenv,
+  lib,
+  ocaml,
+  ocamlPackages,
+  gnum4,
+  fetchFromGitLab,
+}:
+stdenv.mkDerivation rec {
+  pname = "caper";
+  version = "0.9";
+
+  src = fetchFromGitLab {
+    owner = "niksu";
+    repo = "caper";
+    rev = "v${version}";
+    hash = "sha256-TSryjz0NrGdkc+6vmfBqsuVpV3N9FvteTFsVqpUcm0w=";
+  };
+
+  nativeBuildInputs = [
+    ocaml
+    ocamlPackages.ocamlbuild
+    ocamlPackages.findlib
+    ocamlPackages.menhir
+    gnum4
+  ];
+
+  buildInputs = [
+    ocamlPackages.angstrom
+  ];
+
+  strictDeps = true;
+
+  buildPhase = ''
+    runHook preBuild
+    CAPER_WITH_ENGLISH=yes bash build.sh caper.native
+    runHook postBuild
+  '';
+
+  installPhase = ''
+    runHook preInstall
+    mkdir -p $out/bin
+    cp caper.native $out/bin/caper
+    runHook postInstall
+  '';
+
+  meta = {
+    description = "Tool for understanding and processing pcap (packet capture) expressions";
+    longDescription = ''
+      Caper is a tool for understanding and processing "pcap expressions" (also known as *tcpdump filters*) which are used for network packet analysis.
+      Caper can be used for:
+      * Expanding out pcap expressions "in full" to understand their implicit features.
+      * Reasoning about whether two expressions accept the same set of packets, or how their accepted packets differ.
+      * Converting pcap expressions into BPF programs.
+      * Converting between pcap expressions and English.
+
+      More info can be found in the Caper paper (https://www.nik.network/caper/pcap_semantics.pdf).
+    '';
+    homepage = "https://gitlab.com/niksu/caper";
+    license = lib.licenses.gpl3Plus;
+    maintainers = with lib.maintainers; [ willow_ch ];
+    mainProgram = "caper";
+  };
+}