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+---
+title: Use Single Dependency Versions Across Monorepo
+impact: MEDIUM
+impactDescription: avoids duplicate bundles, version conflicts
+tags: monorepo, dependencies, installation
+---
+
+## Use Single Dependency Versions Across Monorepo
+
+Use a single version of each dependency across all packages in your monorepo.
+Prefer exact versions over ranges. Multiple versions cause duplicate code in
+bundles, runtime conflicts, and inconsistent behavior across packages.
+
+Use a tool like syncpack to enforce this. As a last resort, use yarn resolutions
+or npm overrides.
+
+**Incorrect (version ranges, multiple versions):**
+
+```json
+// packages/app/package.json
+{
+  "dependencies": {
+    "react-native-reanimated": "^3.0.0"
+  }
+}
+
+// packages/ui/package.json
+{
+  "dependencies": {
+    "react-native-reanimated": "^3.5.0"
+  }
+}
+```
+
+**Correct (exact versions, single source of truth):**
+
+```json
+// package.json (root)
+{
+  "pnpm": {
+    "overrides": {
+      "react-native-reanimated": "3.16.1"
+    }
+  }
+}
+
+// packages/app/package.json
+{
+  "dependencies": {
+    "react-native-reanimated": "3.16.1"
+  }
+}
+
+// packages/ui/package.json
+{
+  "dependencies": {
+    "react-native-reanimated": "3.16.1"
+  }
+}
+```
+
+Use your package manager's override/resolution feature to enforce versions at
+the root. When adding dependencies, specify exact versions without `^` or `~`.