diff --git a/.envrc b/.envrc
new file mode 100644
index 0000000..247a291
--- /dev/null
+++ b/.envrc
@@ -0,0 +1,3 @@
+source_url "https://raw.githubusercontent.com/cachix/devenv/95f329d49a8a5289d31e0982652f7058a189bfca/direnvrc" "sha256-d+8cBpDfDBj41inrADaJt+bDWhOktwslgoP5YiGJ1v0="
+
+use devenv
diff --git a/.gitignore b/.gitignore
index 40e5032..61fb62a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,4 @@
 /_/
+
+.devenv*
+.direnv
diff --git a/.vscode/extensions.json b/.vscode/extensions.json
index e02a1d6..715994c 100644
--- a/.vscode/extensions.json
+++ b/.vscode/extensions.json
@@ -1,3 +1,7 @@
 {
-  "recommendations": ["esbenp.prettier-vscode", "jnoortheen.nix-ide"]
+  "recommendations": [
+    "esbenp.prettier-vscode",
+    "jnoortheen.nix-ide",
+    "mkhl.direnv"
+  ]
 }
diff --git a/.vscode/settings.json b/.vscode/settings.json
index 21ad8b5..b734ecf 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -3,6 +3,7 @@
 
   "editor.formatOnSave": true,
 
+  "nix.formatterPath": "nixpkgs-fmt",
   "nix.enableLanguageServer": true,
   "nix.serverPath": "nixd",
 
diff --git a/devenv.lock b/devenv.lock
new file mode 100644
index 0000000..2305638
--- /dev/null
+++ b/devenv.lock
@@ -0,0 +1,116 @@
+{
+  "nodes": {
+    "devenv": {
+      "locked": {
+        "dir": "src/modules",
+        "lastModified": 1728740426,
+        "owner": "cachix",
+        "repo": "devenv",
+        "rev": "ef61728d91ad5eb91f86cdbcc16070602e7afa16",
+        "type": "github"
+      },
+      "original": {
+        "dir": "src/modules",
+        "owner": "cachix",
+        "repo": "devenv",
+        "type": "github"
+      }
+    },
+    "flake-compat": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1696426674,
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "rev": "0f9255e01c2351cc7d116c072cb317785dd33b33",
+        "type": "github"
+      },
+      "original": {
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "type": "github"
+      }
+    },
+    "gitignore": {
+      "inputs": {
+        "nixpkgs": [
+          "pre-commit-hooks",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1709087332,
+        "owner": "hercules-ci",
+        "repo": "gitignore.nix",
+        "rev": "637db329424fd7e46cf4185293b9cc8c88c95394",
+        "type": "github"
+      },
+      "original": {
+        "owner": "hercules-ci",
+        "repo": "gitignore.nix",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1728538411,
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "b69de56fac8c2b6f8fd27f2eca01dcda8e0a4221",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs-stable": {
+      "locked": {
+        "lastModified": 1728627514,
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "c505ebf777526041d792a49d5f6dd4095ea391a7",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-24.05",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "pre-commit-hooks": {
+      "inputs": {
+        "flake-compat": "flake-compat",
+        "gitignore": "gitignore",
+        "nixpkgs": [
+          "nixpkgs"
+        ],
+        "nixpkgs-stable": "nixpkgs-stable"
+      },
+      "locked": {
+        "lastModified": 1728778939,
+        "owner": "cachix",
+        "repo": "pre-commit-hooks.nix",
+        "rev": "ff68f91754be6f3427e4986d7949e6273659be1d",
+        "type": "github"
+      },
+      "original": {
+        "owner": "cachix",
+        "repo": "pre-commit-hooks.nix",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "devenv": "devenv",
+        "nixpkgs": "nixpkgs",
+        "pre-commit-hooks": "pre-commit-hooks"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/devenv.nix b/devenv.nix
new file mode 100644
index 0000000..7de7593
--- /dev/null
+++ b/devenv.nix
@@ -0,0 +1,14 @@
+{ pkgs, ... }:
+
+{
+  packages = with pkgs; [
+    nixfmt-rfc-style
+  ];
+
+  # https://github.com/cachix/devenv/blob/main/src/modules/languages/nix.nix
+  # https://devenv.sh/supported-languages/nix
+  languages.nix = {
+    enable = true;
+    lsp.package = pkgs.nixd;
+  };
+}
diff --git a/devenv.yaml b/devenv.yaml
new file mode 100644
index 0000000..397b9cb
--- /dev/null
+++ b/devenv.yaml
@@ -0,0 +1,7 @@
+# yaml-language-server: $schema=https://devenv.sh/devenv.schema.json
+
+inputs:
+  nixpkgs:
+    url: github:nixos/nixpkgs/nixpkgs-unstable
+
+allowUnfree: true