diff --git a/.eslintrc.yml b/.eslintrc.yml
new file mode 100644
index 0000000..6135275
--- /dev/null
+++ b/.eslintrc.yml
@@ -0,0 +1,28 @@
+env:
+  es2021: true
+  node: true
+extends:
+  - eslint:recommended
+  - plugin:@typescript-eslint/recommended
+parser: '@typescript-eslint/parser'
+parserOptions:
+  ecmaVersion: latest
+  sourceType: module
+plugins:
+  - '@typescript-eslint'
+rules:
+  indent:
+    - error
+    - 2
+  linebreak-style:
+    - error
+    - unix
+  quotes:
+    - error
+    - double
+  semi:
+    - error
+    - always
+  comma-dangle:
+    - error
+    - always-multiline
diff --git a/README.md b/README.md
index 021c9ea..dc08681 100644
--- a/README.md
+++ b/README.md
@@ -36,11 +36,19 @@ This section includes the issues, changes & improvements I've made, with the tho
   - Outdated dependencies.
     > Related dependencies: `body-parser`, `dotenv`, `express`, `mongoose`, `@types/cors`, `@types/express`,
     > `@typescript-eslint/eslint-plugin`, `@typescript-eslint/parser`, `eslint`, `ts-node-dev`, `typescript`
+    >
+    > Note: As of this moment, the latest `typescript` version
+    > officially supported by the `@typescript-eslint/typescript-estree` is `4.5.5`
   - Not using exact versions for dependencies.
     > This issue has somewhat similar effects as the `package-lock.json` issue,
     > as `^version` will allow any semver compatible version to be installed.
+- Missing `eslint` config.
+  > The `eslint` config allows to enforce the desired code style among all the contributors.
 - Issues in the `src` directory:
   - Unused imports. (e.g. unused `lodash` import in the `src/scripts/seed.ts`)
+  - Using `var` to define variables.
+    > This way the variable would be defined/redefined globally which could cause problems.
+    > Instead of `var`, it's best to use `let` or `const`. 
 
 ### Improvements
 
diff --git a/package-lock.json b/package-lock.json
index b6c7ac1..030b975 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -22,7 +22,7 @@
         "@typescript-eslint/parser": "5.13.0",
         "eslint": "8.10.0",
         "ts-node-dev": "1.1.8",
-        "typescript": "4.6.2"
+        "typescript": "4.5.5"
       },
       "engines": {
         "node": ">=16.14.0"
@@ -2637,9 +2637,9 @@
       }
     },
     "node_modules/typescript": {
-      "version": "4.6.2",
-      "resolved": "https://registry.npmjs.org/typescript/-/typescript-4.6.2.tgz",
-      "integrity": "sha512-HM/hFigTBHZhLXshn9sN37H085+hQGeJHJ/X7LpBWLID/fbc2acUMfU+lGD98X81sKP+pFa9f0DZmCwB9GnbAg==",
+      "version": "4.5.5",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-4.5.5.tgz",
+      "integrity": "sha512-TCTIul70LyWe6IJWT8QSYeA54WQe8EjQFU4wY52Fasj5UKx88LNYKCgBEHcOMOrFF1rKGbD8v/xcNWVUq9SymA==",
       "dev": true,
       "bin": {
         "tsc": "bin/tsc",
@@ -4668,9 +4668,9 @@
       }
     },
     "typescript": {
-      "version": "4.6.2",
-      "resolved": "https://registry.npmjs.org/typescript/-/typescript-4.6.2.tgz",
-      "integrity": "sha512-HM/hFigTBHZhLXshn9sN37H085+hQGeJHJ/X7LpBWLID/fbc2acUMfU+lGD98X81sKP+pFa9f0DZmCwB9GnbAg==",
+      "version": "4.5.5",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-4.5.5.tgz",
+      "integrity": "sha512-TCTIul70LyWe6IJWT8QSYeA54WQe8EjQFU4wY52Fasj5UKx88LNYKCgBEHcOMOrFF1rKGbD8v/xcNWVUq9SymA==",
       "dev": true
     },
     "unpipe": {
diff --git a/package.json b/package.json
index 37daee7..ef150e1 100644
--- a/package.json
+++ b/package.json
@@ -23,7 +23,9 @@
     "seed": "ts-node-dev src/scripts/seed.ts",
     "start": "node .build/api.js",
     "build": "tsc",
-    "build:watch": "npm run build -- --watch"
+    "build:watch": "npm run build -- --watch",
+    "lint": "eslint src",
+    "lint:fix": "npm run lint -- --fix"
   },
   "dependencies": {
     "body-parser": "1.19.2",
@@ -39,6 +41,6 @@
     "@typescript-eslint/parser": "5.13.0",
     "eslint": "8.10.0",
     "ts-node-dev": "1.1.8",
-    "typescript": "4.6.2"
+    "typescript": "4.5.5"
   }
 }
diff --git a/src/api.ts b/src/api.ts
index e9725f6..5a0e250 100644
--- a/src/api.ts
+++ b/src/api.ts
@@ -22,5 +22,5 @@ app.use(profileRouter);
 app.use(simulatorRouter);
 
 app.listen(PORT, () =>
-  console.log(`✅  Ready on port http://localhost:${PORT}`)
+  console.log(`✅  Ready on port http://localhost:${PORT}`),
 );
diff --git a/src/models/Favorite.ts b/src/models/Favorite.ts
index ec4ffa3..a227a76 100644
--- a/src/models/Favorite.ts
+++ b/src/models/Favorite.ts
@@ -12,7 +12,7 @@ const schema = new Schema(
   },
   {
     timestamps: true,
-  }
+  },
 );
 
 export const Favorite = mongoose.model("Favorite", schema);
diff --git a/src/models/Simulator.ts b/src/models/Simulator.ts
index 51b15d0..d86a8a3 100644
--- a/src/models/Simulator.ts
+++ b/src/models/Simulator.ts
@@ -13,7 +13,7 @@ const schema = new Schema(
   },
   {
     timestamps: true,
-  }
+  },
 );
 
 export const Simulator = mongoose.model("Simulator", schema);
diff --git a/src/routes/profile.router.ts b/src/routes/profile.router.ts
index 3dd2d87..2bffca1 100644
--- a/src/routes/profile.router.ts
+++ b/src/routes/profile.router.ts
@@ -1,16 +1,16 @@
 import { Profile } from "#src/models/Profile.js";
 import express from "express";
 
-export var router = express.Router();
+export const router = express.Router();
 
 router.get("/api/profile", async (req, res) => {
-  var profile = await Profile.find().lean();
+  const profile = await Profile.find().lean();
   console.log(profile);
   res.json({ profile });
 });
 
 router.post("/api/profile", async (req, res) => {
-  var { email, name, nickname } = req.body;
+  const { email, name, nickname } = req.body;
 
   let profile = await Profile.findOne({
     $or: [{ email }, { nickname }],
diff --git a/src/routes/simulator.router.ts b/src/routes/simulator.router.ts
index 562b07e..d9a1125 100644
--- a/src/routes/simulator.router.ts
+++ b/src/routes/simulator.router.ts
@@ -2,13 +2,13 @@ import { Simulator } from "#src/models/Simulator.js";
 import cors from "cors";
 import express from "express";
 
-var app = express();
+const app = express();
 app.use(cors());
 
-export var router = express.Router();
+export const router = express.Router();
 
 router.get("/api/simulator", async (req, res) => {
-  var simulator = await Simulator.find().lean();
+  const simulator = await Simulator.find().lean();
   console.log(simulator);
   res.json({ simulator });
 });
@@ -16,20 +16,20 @@ router.get("/api/simulator", async (req, res) => {
 router.get("/api/simulator/:profile_id", async (req, res) => {
   console.log("========== ");
   let query = {};
-  var { profile_id } = req.params;
+  const { profile_id } = req.params;
   console.log({ profile_id });
   query = { profile_id };
-  var data = await Simulator.find(query);
+  const data = await Simulator.find(query);
   res.json(data);
 });
 
 router.post("/api/simulator/:profile_id", async (req, res) => {
-  var { profile_id } = req.params;
-  var newData = {
+  const { profile_id } = req.params;
+  const newData = {
     ...req.body,
     profile_id,
   };
   console.log(newData);
-  var simulator = await Simulator.create(newData);
+  const simulator = await Simulator.create(newData);
   res.json(simulator);
 });
diff --git a/src/scripts/seed.ts b/src/scripts/seed.ts
index 29f2dfb..f200c27 100644
--- a/src/scripts/seed.ts
+++ b/src/scripts/seed.ts
@@ -9,11 +9,11 @@ import mongoose from "mongoose";
   mongoose.connect(DBURL);
 
   const profile = new Profile({
-    name: `String`,
-    email: `String`,
-    capital: `123`,
-    divisa: `String`,
-    prefered_cryptocurrency: `String`,
+    name: "String",
+    email: "String",
+    capital: "123",
+    divisa: "String",
+    prefered_cryptocurrency: "String",
   });
   await profile.save();
 
@@ -24,22 +24,22 @@ import mongoose from "mongoose";
 
   const simulator = new Simulator({
     profile_id: idProfile,
-    name: `String`,
-    start_date: `01/05/2021`,
-    check_date: `01/05/2021`,
-    cryptocurrency: `String`,
-    divisa: `String`,
-    Crypto_price_start: `123`,
-    Crypto_price_check: `123`,
+    name: "String",
+    start_date: "01/05/2021",
+    check_date: "01/05/2021",
+    cryptocurrency: "String",
+    divisa: "String",
+    Crypto_price_start: "123",
+    Crypto_price_check: "123",
   });
   await simulator.save();
 
   const favorite = new Favorite({
     profile_id: idProfile,
-    name: `String`,
-    favorite1: `String`,
-    favorite2: `String`,
-    favorite3: `String`,
+    name: "String",
+    favorite1: "String",
+    favorite2: "String",
+    favorite3: "String",
   });
   await favorite.save();