diff --git a/.gitignore b/.gitignore
new file mode 100644
index 00000000..e2f5dd2e
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+result
\ No newline at end of file
diff --git a/README.md b/README.md
new file mode 100644
index 00000000..19735b27
--- /dev/null
+++ b/README.md
@@ -0,0 +1,112 @@
+# Repl.it Nix Modules
+
+This repository holds Repl.it's Nix modules.
+
+* Each module is located as a folder under `pkgs/modules`
+* `pkgs/modules/default.nix` specifies a list of the active modules, some of which are parameterized with the version of the runtime or compiler
+
+To list all active modules, you can do:
+
+```
+nix eval .#modules --json | jq
+```
+Output might look like:
+```json
+{
+  "bun-0.5-m1.0": "/nix/store/nqwdhvs2n6fv82nkn77rg5wb3g1giwjs-replit-module-bun-0.5-m1.0",
+  "c-14.0-m1.0": "/nix/store/c8v74sbwivlj0mridwsdng883frwccy5-replit-module-c-14.0-m1.0",
+  "clojure-1.11-m1.0": "/nix/store/dsx4w6inr69f6c799qija5nf08q1ds39-replit-module-clojure-1.11-m1.0",
+  "cpp-14.0-m1.0": "/nix/store/065sbbghckzyirbxq239s4y3bcsr2wq2-replit-module-cpp-14.0-m1.0",
+  "dart-2.18-m1.0": "/nix/store/ampynbffmbjckc4xqzndlhbxncdljqfv-replit-module-dart-2.18-m1.0",
+  "dotnet-7.0-m1.0": "/nix/store/nkq2y69kfbbjxrr9dvc385nskqs0cd67-replit-module-dotnet-7.0-m1.0",
+  "go-1.19-m1.0": "/nix/store/g1vrclpr65ynpldn7a6yvjsniaj3fb3r-replit-module-go-1.19-m1.0",
+  "haskell-9.0-m1.0": "/nix/store/7l7mafijx1lrxs85k6vzr3q5xzxi02fb-replit-module-haskell-9.0-m1.0",
+  "java-22.3-m1.0": "/nix/store/v09kxcfkm66bks2lxv5hknxh8i4ijzq9-replit-module-java-22.3-m1.0",
+  "lua-5.2-m1.0": "/nix/store/3g185mb4bzn2g9w0b7shw39x6ybby0g6-replit-module-lua-5.2-m1.0",
+  "nodejs-14.21-m1.1": "/nix/store/1igqvvk7agkxvz0ibi7vlsdkxnx5hnrj-replit-module-nodejs-14.21-m1.1",
+  "nodejs-16.18-m1.1": "/nix/store/751zzdn9cl7g4qx04k5szxm3jynfqa03-replit-module-nodejs-16.18-m1.1",
+  "nodejs-18.12-m1.1": "/nix/store/a1i4r09lc1qrnzcwv5bkfscc8nxk8b44-replit-module-nodejs-18.12-m1.1",
+  "nodejs-19.1-m1.1": "/nix/store/azs3v09dm03v27zrvhvhs7j1h5zm0y2s-replit-module-nodejs-19.1-m1.1",
+  "php-8.1-m1.0": "/nix/store/z9x4avlw2s0cmaqglbzb3ymb7cgv7hm4-replit-module-php-8.1-m1.0",
+  "python-3.10-m1.0": "/nix/store/ihcaap76i6xp3hzfayg6a0krx1pb5w52-replit-module-python-3.10-m1.0",
+  "qbasic-0.0-m1.1": "/nix/store/rpb9dg8c8cwiszfxa1xhw7z06yh59vn3-replit-module-qbasic-0.0-m1.1",
+  "r-4.2-m1.0": "/nix/store/c7wcs687dkxvfak0dr2gnb5ll69bv6yf-replit-module-r-4.2-m1.0",
+  "ruby-3.1-m1.0": "/nix/store/rxmyz9gv677v06jz64pqs7a9g2ppw0mj-replit-module-ruby-3.1-m1.0",
+  "rust-1.64-m1.0": "/nix/store/v2wq17m6chbxgv4vk2r4p4bqjp5r80vn-replit-module-rust-1.64-m1.0",
+  "swift-5.6-m1.0": "/nix/store/qp9bvj042a855xd4i0hrqbwz0p81zp4k-replit-module-swift-5.6-m1.0",
+  "web-3.0-m1.0": "/nix/store/37kafc7qxhji91175lgccmn2yx1dzw9m-replit-module-web-3.0-m1.0"
+}
+```
+
+To build modules, you can do:
+
+```
+nix build .#bundle
+```
+
+which will create a `result` directory containing a symlink for each active module.
+
+## Lock Modules
+
+`lock_modules.py` is a script that generates a module registry file `modules.json`.
+It should be run each time when before publishing a PR (but after committing your changes):
+
+```
+$ nix develop
+$ python lock_modules.py
+```
+
+`modules.json` is similar to a lock file in used in common packagers in that it fixes
+the exact version of each module. This file looks something like:
+
+```json
+{
+  "modules": {
+    "nodejs-18.12-m1.1": {
+      "commit": "4ec006c0eb247320e77c0abbf46b6f9e33370f81",
+      "created": "2023-05-04T16:52:42-04:00",
+      "path": "/nix/store/a1i4r09lc1qrnzcwv5bkfscc8nxk8b44-replit-module-nodejs-18.12-m1.1"
+    },
+    "nodejs-19.1-m1.1": {
+      "commit": "4ec006c0eb247320e77c0abbf46b6f9e33370f81",
+      "created": "2023-05-04T16:52:42-04:00",
+      "path": "/nix/store/azs3v09dm03v27zrvhvhs7j1h5zm0y2s-replit-module-nodejs-19.1-m1.1"
+    },
+    "go-1.19-m1.0": {
+      "commit": "4ec006c0eb247320e77c0abbf46b6f9e33370f81",
+      "created": "2023-05-04T16:52:42-04:00",
+      "path": "/nix/store/g1vrclpr65ynpldn7a6yvjsniaj3fb3r-replit-module-go-1.19-m1.0"
+    }
+  },
+  "aliases": {
+    "nodejs": "nodejs-19.1-m1.1",
+    "nodejs-18.12": "nodejs-18.12-m1.1",
+    "nodejs-18.12-m1": "nodejs-18.12-m1.1",
+    "nodejs-19.1": "nodejs-19.1-m1.1",
+    "nodejs-19.1-m1": "nodejs-19.1-m1.1",
+    "go": "go-1.19-m1.0",
+    "go-1.19": "go-1.19-m1.0",
+    "go-1.19-m1": "go-1.19-m1.0"
+  }
+}
+```
+
+The modules section is an append-only section. This means the contents of the value under a key, say `nodejs-19.1-m1.1`
+cannot be changed. Each module contains:
+
+* commit - the git commit of the repo when `lock_modules.py` was ran. The script requires a clean working directory,
+unless the `-d` flag is supplied
+* created - the timestamp of the commit
+* path - the output path of the module as returned by the `nix eval .#modules --json` command
+
+The aliases section points to the latest version of each module for a given shortened version specifier.
+
+If you made a modification in a module or a dependency of a module, re-running `lock_modules.py` will fail
+an error like:
+```
+Exception: go-1.19-m1.0 changed from /nix/store/g1vrclpr65ynpldn7a6yvjsniaj3fb3r-replit-module-go-1.19-m1.0 to /nix/store/pbrqcayg3ahawdld7j5kay97xli8zi0a-replit-module-go-1.19-m1.0
+```
+
+To move forward, you'll have to increment the version of the associated module.
+
+See more about the versioning scheme at: https://replit.com/@util/Design-docs#goval/nixmodules_versions.md
\ No newline at end of file
diff --git a/flake.lock b/flake.lock
index d4881f3c..05a66b96 100644
--- a/flake.lock
+++ b/flake.lock
@@ -1,5 +1,20 @@
 {
   "nodes": {
+    "flake-utils": {
+      "locked": {
+        "lastModified": 1667395993,
+        "narHash": "sha256-nuEHfE/LcWyuSWnS8t12N1wc105Qtau+/OdUAjtQ0rA=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "5aed5285a952e0b949eb3ba02c12fa4fcfef535f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
     "nixmodules-stable": {
       "inputs": {
         "nixpkgs": "nixpkgs"
@@ -51,10 +66,47 @@
         "type": "github"
       }
     },
+    "nixpkgs_3": {
+      "locked": {
+        "lastModified": 1670276674,
+        "narHash": "sha256-FqZ7b2RpoHQ/jlG6JPcCNmG/DoUPCIvyaropUDFhF3Q=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "52e3e80afff4b16ccb7c52e9f0f5220552f03d04",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-22.11",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "prybar": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs_3"
+      },
+      "locked": {
+        "lastModified": 1683237785,
+        "narHash": "sha256-l4JoUTwISecR5DyBY3ShEvPxCV1F0l7FtH/bNWweUtY=",
+        "owner": "replit",
+        "repo": "prybar",
+        "rev": "65f486534054665f1b333689417c39acd370d3a5",
+        "type": "github"
+      },
+      "original": {
+        "owner": "replit",
+        "repo": "prybar",
+        "rev": "65f486534054665f1b333689417c39acd370d3a5",
+        "type": "github"
+      }
+    },
     "root": {
       "inputs": {
         "nixmodules-stable": "nixmodules-stable",
-        "nixpkgs": "nixpkgs_2"
+        "nixpkgs": "nixpkgs_2",
+        "prybar": "prybar"
       }
     }
   },
diff --git a/flake.nix b/flake.nix
index 7fdebd82..3c6997a1 100644
--- a/flake.nix
+++ b/flake.nix
@@ -2,13 +2,15 @@
   description = "Nix expressions for defining Replit development environments";
   inputs.nixpkgs.url = "github:nixos/nixpkgs?rev=52e3e80afff4b16ccb7c52e9f0f5220552f03d04";
   inputs.nixmodules-stable.url = "github:replit/nixmodules?rev=d77c07009d6d0e09eaf7aa011cad530a644eca01";
+  inputs.prybar.url = "github:replit/prybar?rev=65f486534054665f1b333689417c39acd370d3a5";
 
-  outputs = { self, nixpkgs, nixmodules-stable, ... }:
+  outputs = { self, nixpkgs, nixmodules-stable, prybar, ... }:
     let
       mkPkgs = system: import nixpkgs {
         inherit system;
-        overlays = [ self.overlays.default ]; # ++ import ;
+        overlays = [ self.overlays.default prybar.overlays.default ]; # ++ import ;
       };
+
       pkgs = mkPkgs "x86_64-linux";
     in
     {
@@ -16,6 +18,16 @@
         moduleit = self.packages.${prev.system}.moduleit;
       };
       formatter.x86_64-linux = pkgs.nixpkgs-fmt;
-      packages.x86_64-linux = import ./pkgs { inherit pkgs self nixpkgs nixmodules-stable; };
+      packages.x86_64-linux = import ./pkgs {
+        inherit pkgs self nixpkgs nixmodules-stable; 
+      };
+      devShells.x86_64-linux.default = pkgs.mkShell {
+        packages = [
+          pkgs.python310
+        ];
+      };
+      modules = import ./pkgs/modules {
+        inherit pkgs;
+      };
     };
 }
diff --git a/lock_modules.py b/lock_modules.py
new file mode 100644
index 00000000..8b04c69e
--- /dev/null
+++ b/lock_modules.py
@@ -0,0 +1,136 @@
+import subprocess
+import json
+import os
+import re
+import argparse
+
+module_id_regex = re.compile(r'^([a-zA-Z0-9.]+)-([a-zA-Z0-9.]+)-m([0-9]+)\.([0-9]+)$')
+module_registry_file = 'modules.json'
+
+def get_commit_info():
+  output = subprocess.check_output(['git', 'show', '-s', '--format=format:%aI|%H'])
+  timestamp, commit = str(output, 'UTF-8').split('|')
+  return {
+    'sha': commit,
+    'timestamp': timestamp
+  }
+
+def is_working_directory_clean():
+  output = subprocess.check_output(['git', 'status', '--porcelain', '--untracked-files=no'])
+  return len(output) == 0
+
+def get_current_modules():
+  output = subprocess.check_output(['nix', 'eval', '.#modules', '--json'])
+  return json.loads(output)
+
+def get_module_registry():
+  if not os.path.isfile(module_registry_file):
+    return { 'modules': {}, 'aliases': {} }
+  f = open(module_registry_file, 'r')
+  registry = json.load(f)
+  f.close()
+  return registry
+
+def save_module_registry(registry):
+  f = open(module_registry_file, 'w')
+  json.dump(registry, f, indent = 2)
+  f.close()
+  print('Wrote %s' % module_registry_file)
+
+def parse_module_id(module_id):
+  match = module_id_regex.match(module_id)
+  id, community_version, major, minor = match.groups()
+  return {
+    'id': id,
+    'community_version': community_version,
+    'major': major,
+    'minor': minor,
+  }
+
+def is_version_greater(modinfo1, modinfo2):
+  if modinfo1['community_version'] == modinfo2['community_version']:
+    if modinfo1['major'] == modinfo2['major']:
+      return modinfo1['minor'] > modinfo2['minor']
+    return modinfo1['major'] > modinfo2['major']
+  return is_semver_greater(modinfo1['community_version'], modinfo2['community_version'])
+
+def is_semver_greater(semver1, semver2):
+  parts1 = list(map(int, semver1.split('.')))
+  parts2 = list(map(int, semver2.split('.')))
+  assert len(parts1) == len(parts2), "comparing semvars that have different number of parts: %s vs %s" % (semver1, semver2)
+  for i in range(len(parts1)):
+    if parts1[i] > parts2[i]:
+      return True
+  return False
+
+def generate_aliases(module_registry):
+  aliases = {}
+  for module_id in module_registry.keys():
+    modinfo = parse_module_id(module_id)
+    short_alias = modinfo['id']
+    medium_alias = "%s-%s" % (modinfo['id'], modinfo['community_version'])
+    long_alias = "%s-%s-m%s" % (modinfo['id'], modinfo['community_version'], modinfo['major'])
+
+    if short_alias not in aliases or is_version_greater(modinfo, parse_module_id(aliases[short_alias])):
+      aliases[short_alias] = module_id
+    if medium_alias not in aliases or is_version_greater(modinfo, parse_module_id(aliases[medium_alias])):
+      aliases[medium_alias] = module_id
+    if long_alias not in aliases or is_version_greater(modinfo, parse_module_id(aliases[long_alias])):
+      aliases[long_alias] = module_id
+  return aliases
+
+def update_module_registry(module_registry):
+  commit = get_commit_info()
+  modules = get_current_modules()
+  changed = False
+  for module_id, module_path in modules.items():
+    if module_id in module_registry:
+      # check for conflict
+      prev_path = module_registry[module_id]['path']
+      if module_path != prev_path:
+        raise Exception('%s changed from %s to %s' % (module_id, prev_path, module_path))
+      else:
+        print('%s unchanged' % module_id)
+        continue
+
+    module_registry[module_id] = {
+      'commit': commit['sha'],
+      'created': commit['timestamp'],
+      'path': module_path
+    }
+    print('%s added' % module_id)
+    changed = True
+  return changed
+
+def main():
+  parser = argparse.ArgumentParser(
+    prog='lock_modules',
+    description='upserts current modules to %s' % module_registry_file,
+  )
+
+  parser.add_argument('-d', '--dirty', action='store_true')
+  parser.add_argument('-v', '--verify', action='store_true')
+
+  args = parser.parse_args()
+
+  if not args.dirty and not is_working_directory_clean():
+    print('There are uncommitted changes. Exiting.')
+    exit(1)
+
+  module_registry_top_level = get_module_registry()
+  module_registry = module_registry_top_level['modules']
+  changed = update_module_registry(module_registry)
+
+  if args.verify and changed:
+    print('%s is not up to date!!' % module_registry_file)
+    exit(1)
+
+  if changed:
+    aliases = generate_aliases(module_registry)
+    save_module_registry({
+      'modules': module_registry,
+      'aliases': aliases
+    })
+
+if __name__ == '__main__':
+  main()
\ No newline at end of file
diff --git a/pkgs/default.nix b/pkgs/default.nix
index bfd629b1..6cfc1d86 100644
--- a/pkgs/default.nix
+++ b/pkgs/default.nix
@@ -3,31 +3,17 @@
 with pkgs.lib;
 
 let
-  mkModule = path: pkgs.callPackage ./moduleit/entrypoint.nix {
-    configPath = path;
-  };
+  modules = self.modules;
   revstring_long = self.rev or "dirty";
   revstring = builtins.substring 0 7 revstring_long;
-
-  modules = rec {
-    go = go_1;
-    go_1 = mkModule ./go;
-
-    rust = rust_1;
-    rust_1 = mkModule ./rust;
-
-    swift = swift_1;
-    swift_1 = mkModule ./swift;
-  };
-
-  modulesList = (mapAttrsToList (name: value: { inherit name; path = value;}) modules);
-
 in
 rec {
   default = moduleit;
   moduleit = pkgs.callPackage ./moduleit { };
 
-  bundle = pkgs.linkFarm "nixmodules-bundle-${revstring}" modulesList;
+  bundle = pkgs.linkFarm "nixmodules-bundle-${revstring}" (
+    mapAttrsToList (name: value: { inherit name; path = value;}) modules
+  );
 
   bundle-stable = nixmodules-stable.packages.${pkgs.system}.bundle;
 
diff --git a/pkgs/moduleit/entrypoint.nix b/pkgs/moduleit/entrypoint.nix
index f43a55e0..6c63107a 100644
--- a/pkgs/moduleit/entrypoint.nix
+++ b/pkgs/moduleit/entrypoint.nix
@@ -1,7 +1,6 @@
 { pkgs ? import <nixpkgs> { }
 , configPath
 }:
-
 (pkgs.lib.evalModules {
   modules = [
     configPath
diff --git a/pkgs/moduleit/module-definition.nix b/pkgs/moduleit/module-definition.nix
index 8d60ce09..e0efa529 100644
--- a/pkgs/moduleit/module-definition.nix
+++ b/pkgs/moduleit/module-definition.nix
@@ -465,6 +465,11 @@ in
 
 {
   options = {
+    id = mkOption {
+      type = types.str;
+      description = "ID of the module";
+    };
+
     name = mkOption {
       type = types.str;
       description = "Name of the module";
@@ -476,6 +481,11 @@ in
       default = "";
     };
 
+    community-version = mkOption {
+      type = types.str;
+      description = "The version of the language or framework provided by this module.";
+    };
+
     version = mkOption {
       type = types.str;
       description = "Version of the module";
@@ -575,8 +585,10 @@ in
       let
 
         moduleJSON = {
+          id = config.id;
           name = config.name;
           description = config.description;
+          community-version = config.community-version;
           version = config.version;
           env = {
             PATH = lib.makeBinPath config.packages;
@@ -590,6 +602,6 @@ in
         };
 
       in
-      pkgs.writeText "replit-module-${config.name}-${config.version}" (builtins.toJSON moduleJSON);
+      pkgs.writeText "replit-module-${config.id}-${config.community-version}-m${config.version}" (builtins.toJSON moduleJSON);
   };
 }
diff --git a/pkgs/modules/default.nix b/pkgs/modules/default.nix
new file mode 100644
index 00000000..e699a565
--- /dev/null
+++ b/pkgs/modules/default.nix
@@ -0,0 +1,23 @@
+{ pkgs }:
+let
+  mkModule = path: pkgs.callPackage ../moduleit/entrypoint.nix {
+    configPath = path;
+  };
+  
+  modulesList = [
+    (mkModule ./go)
+    (mkModule ./rust)
+    (mkModule ./swift)
+  ];
+
+  modules = builtins.listToAttrs (
+    map (module: { name = get-module-id module; value = module; }) modulesList
+  );
+
+  get-module-id = module:
+    let
+      match = builtins.match "^\/nix\/store\/([^-]+)-replit-module-(.+)$" module.outPath;
+    in
+      builtins.elemAt match 1;
+in
+  modules
\ No newline at end of file
diff --git a/pkgs/go/default.nix b/pkgs/modules/go/default.nix
similarity index 76%
rename from pkgs/go/default.nix
rename to pkgs/modules/go/default.nix
index 65ec7338..e51ac80c 100644
--- a/pkgs/go/default.nix
+++ b/pkgs/modules/go/default.nix
@@ -1,6 +1,11 @@
-{ pkgs, ... }:
+{ pkgs, lib, ... }:
+let
+  goversion = lib.versions.majorMinor pkgs.go.version;
+in
 {
-  name = "GoTools";
+  id = "go";
+  name = "Go Tools";
+  community-version = goversion;
   version = "1.0";
 
   packages = with pkgs; [
diff --git a/pkgs/rust/default.nix b/pkgs/modules/rust/default.nix
similarity index 88%
rename from pkgs/rust/default.nix
rename to pkgs/modules/rust/default.nix
index 0347e0e2..d11f525f 100644
--- a/pkgs/rust/default.nix
+++ b/pkgs/modules/rust/default.nix
@@ -1,4 +1,4 @@
-{ pkgs, ... }:
+{ pkgs, lib, ... }:
 let
   cargoRun = pkgs.writeScriptBin "cargo_run" ''
     if [ ! -f "$HOME/$REPL_SLUG/Cargo.toml" ]; then
@@ -8,9 +8,12 @@ let
 
     ${pkgs.cargo}/bin/cargo run
   '';
+  community-version = lib.versions.majorMinor pkgs.rustc.version;
 in
 {
-  name = "RustTools";
+  id = "rust";
+  name = "Rust Tools";
+  inherit community-version;
   version = "1.0";
 
   packages = with pkgs; [
diff --git a/pkgs/swift/default.nix b/pkgs/modules/swift/default.nix
similarity index 84%
rename from pkgs/swift/default.nix
rename to pkgs/modules/swift/default.nix
index 380cdb56..ea87b6dc 100644
--- a/pkgs/swift/default.nix
+++ b/pkgs/modules/swift/default.nix
@@ -1,5 +1,7 @@
-{ pkgs, ... }:
+{ pkgs, lib, ... }:
 let
+  community-version = lib.versions.majorMinor pkgs.swift.version;
+
   swiftc-wrapper = pkgs.stdenv.mkDerivation {
     name = "swiftc-wrapper";
     buildInputs = [ pkgs.makeWrapper ];
@@ -14,7 +16,9 @@ let
   };
 in
 {
-  name = "SwiftTools";
+  id = "swift";
+  name = "Swift Tools";
+  inherit community-version;
   version = "1.0";
 
   packages = with pkgs; [