diff --git a/.env.example b/.env.example
deleted file mode 100644
index 6d05b4ad..00000000
--- a/.env.example
+++ /dev/null
@@ -1 +0,0 @@
-PGURL="postgres://[user]:[password]@[host]/[dbname]"
diff --git a/db/index.js b/db/index.js
index af723442..2577751a 100644
--- a/db/index.js
+++ b/db/index.js
@@ -1,25 +1,19 @@
-// Load our .env file
-require('dotenv').config()
 
-// Require Client obj from the postgres node module
-const { Client } = require("pg");
+const { Pool } = require('pg');
+
+const { PGHOST, PGDATABASE, PGUSER, PGPASSWORD } = process.env;
+
+const dbConnection = new Pool({
+  host: PGHOST,
+  database: PGDATABASE,
+  username: PGUSER,
+  password: PGPASSWORD,
+  port: 5432, 
+  ssl: {
+    require: true,
+  },
+})
+
+module.exports = dbConnection
 
-const client = {
-  query: async (str, values) => {
-    // Get the connection string from process.env -
-    // the dotenv library sets this variable based
-    // on the contents of our env file
-    // Create a new connection to the database using the Client
-    // object provided by the postgres node module
-    const dbClient = new Client(process.env.PGURL)
-    // connect a connection
-    await dbClient.connect()
-    // execute the query
-    const result = await dbClient.query(str, values)
-    // close the connection
-    await dbClient.end()
-    return result
-  }
-}
 
-module.exports = client;
diff --git a/package-lock.json b/package-lock.json
index 37ccdff8..b886cb18 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -12,6 +12,7 @@
         "cors": "^2.8.5",
         "dotenv": "^16.3.1",
         "express": "^4.18.2",
+        "express-async-errors": "^3.1.1",
         "faker": "^5.5.3",
         "morgan": "1.10.0",
         "pg": "8.6.0",
@@ -2064,6 +2065,14 @@
         "node": ">= 0.10.0"
       }
     },
+    "node_modules/express-async-errors": {
+      "version": "3.1.1",
+      "resolved": "https://registry.npmjs.org/express-async-errors/-/express-async-errors-3.1.1.tgz",
+      "integrity": "sha512-h6aK1da4tpqWSbyCa3FxB/V6Ehd4EEB15zyQq9qe75OZBp0krinNKuH4rAY+S/U/2I36vdLAUFSjQJ+TFmODng==",
+      "peerDependencies": {
+        "express": "^4.16.2"
+      }
+    },
     "node_modules/express/node_modules/body-parser": {
       "version": "1.20.1",
       "resolved": "https://registry.npmjs.org/body-parser/-/body-parser-1.20.1.tgz",
diff --git a/package.json b/package.json
index 57d8b4fb..831dbdf6 100644
--- a/package.json
+++ b/package.json
@@ -6,13 +6,19 @@
   "scripts": {
     "start": "npx nodemon src/index.js",
     "test": "npx jest -i test/api/routes --forceExit",
-    "test-extensions": "npx jest -i test/api/extensions  --forceExit"
+    "test-extensions": "npx jest -i test/api/extensions  --forceExit",
+    "test-books": "npx jest -i test/api/routes/books.spec.js --forceExit",
+    "test-books-extensions": "npx jest -i test/api/extensions/books.spec.js --forceExit",
+    "test-pets": "npx jest -i test/api/routes/pets.spec.js --forceExit",
+    "test-pets-extensions": "npx jest -i test/api/extensions/pets.spec.js --forceExit",
+    "test-breeds-extensions": "npx jest -i test/api/extensions/breeds.spec.js --forceExit"
   },
   "dependencies": {
     "body-parser": "^1.20.2",
     "cors": "^2.8.5",
     "dotenv": "^16.3.1",
     "express": "^4.18.2",
+    "express-async-errors": "^3.1.1",
     "faker": "^5.5.3",
     "morgan": "1.10.0",
     "pg": "8.6.0",
diff --git a/src/controllers/booksControllers.js b/src/controllers/booksControllers.js
new file mode 100644
index 00000000..34f1088d
--- /dev/null
+++ b/src/controllers/booksControllers.js
@@ -0,0 +1,104 @@
+const {
+  MissingFieldsError,
+  NoDataError,
+  InvalidParameterError,
+  DataAlreadyExistsError,
+} = require("../errors/errors");
+const {
+  fetchAllBooks,
+  postBook,
+  fetchBookById,
+  updateBookById,
+  deleteBookById,
+  fetchBookByQuery,
+} = require("../dal/bookRepository");
+
+async function getBooksController(req, res) {
+  let books;
+  const query = req.query;
+
+  if (query) {
+    if (query.perPage < 10 || query.perPage > 50) {
+      throw new InvalidParameterError(
+        `parameter invalid perPage: ${query.perPage} not valid. Accepted range is 10 - 50`
+      );
+    }
+    books = await fetchBookByQuery(query);
+  } else {
+    books = await fetchAllBooks();
+  }
+
+  res
+    .status(200)
+    .json({ books, page: Number(query.page), per_page: Number(query.perPage) });
+}
+
+async function addBookController(req, res) {
+  const newBook = req.body;
+  const requiredProperties = [
+    "title",
+    "type",
+    "author",
+    "topic",
+    "publication_date",
+    "pages",
+  ];
+  const allFieldsExist = requiredProperties.every(
+    (property) => newBook[property]
+  );
+  if (!allFieldsExist) {
+    throw new MissingFieldsError(
+      "Books require a title, type, author, topic, publication year, and number of pages"
+    );
+  }
+  const book = await postBook(newBook);
+  res.status(201).json({ book });
+}
+
+async function getBookByIdController(req, res) {
+  targetBookId = Number(req.params.id);
+
+  const book = await fetchBookById(targetBookId);
+  if (!book) {
+    throw new NoDataError(`no book with id: ${targetBookId}`);
+  }
+  res.status(200).json({ book });
+}
+
+async function putBookByIdController(req, res, next) {
+  const targetBookId = Number(req.params.id);
+  const newParams = req.body;
+
+  const allBooks = await fetchAllBooks(); 
+  if (allBooks.find((book) => book.title === newParams.title)) {
+    throw new DataAlreadyExistsError(
+      `A book with the title: ${newParams.title} already exists`
+    );
+  }
+
+  const book = await fetchBookById(targetBookId);
+  if (!book) {
+    throw new NoDataError(`no book with id: ${targetBookId}`);
+  }
+  const updatedBook = await updateBookById(targetBookId, newParams);
+  res.status(201).json({ book: updatedBook });
+}
+
+async function deleteBookByIdController(req, res, next) {
+  const targetBookId = Number(req.params.id);
+
+  const book = await fetchBookById(targetBookId);
+  if (!book) {
+    throw new NoDataError(`no book with id: ${targetBookId}`);
+  }
+  const deletedBook = await deleteBookById(targetBookId);
+  res.status(201).json({ book: deletedBook });
+}
+
+module.exports = {
+  addBookController,
+  getBooksController,
+  getBookByIdController,
+  putBookByIdController,
+  deleteBookByIdController,
+};
diff --git a/src/controllers/breedsControllers.js b/src/controllers/breedsControllers.js
new file mode 100644
index 00000000..12c898b5
--- /dev/null
+++ b/src/controllers/breedsControllers.js
@@ -0,0 +1,9 @@
+const { fetchBreeds } = require("../dal/breedsRepository");
+
+async function getAllBreedsController(req, res) {
+  const breeds = await fetchBreeds(req.query);
+    console.log({ breeds })
+  res.status(200).json({ breeds });
+}
+
+module.exports = { getAllBreedsController };
diff --git a/src/controllers/petsControllers.js b/src/controllers/petsControllers.js
new file mode 100644
index 00000000..8d4ec709
--- /dev/null
+++ b/src/controllers/petsControllers.js
@@ -0,0 +1,94 @@
+const { MissingFieldsError, NoDataError, InvalidParameterError } = require("../errors/errors");
+
+const {
+  fetchAllPets,
+  fetchPetById,
+  updatePetById,
+  addPet,
+  deletePet,
+  fetchPetsWithQuery,
+} = require("../dal/petsRepository");
+
+async function getPetsController(req, res) {
+  let pets;
+
+  if (req.query) {
+    if (req.query.perPage < 10 || req.query.perPage > 50) {
+      throw new InvalidParameterError(`parameter invalid perPage: ${req.query.perPage} not valid. Accepted range is 10 - 50`)
+    }
+    pets = await fetchPetsWithQuery(req.query);
+  } else {
+    pets = await fetchAllPets();
+  }
+
+  res
+    .status(200)
+    .json({
+      pets,
+      page: Number(req.query.page),
+      per_page: Number(req.query.perPage),
+    });
+}
+
+async function getPetsByIdController(req, res) {
+  const id = Number(req.params.id);
+  const pet = await fetchPetById(id);
+
+  if (!pet) {
+    throw new NoDataError(`no pet with id: ${id}`);
+  }
+  res.status(200).json({ pet });
+}
+
+async function updatePetByIdController(req, res) {
+  const id = Number(req.params.id);
+  const updatedParams = req.body;
+
+  const found = await fetchPetById(id)
+  if (!found) {
+      throw new NoDataError(`no pet with id: ${id}`);
+  }
+
+  const pet = await updatePetById(id, updatedParams);
+  res.status(201).json({ pet });
+}
+
+async function addPetController(req, res) {
+  const newPet = req.body;
+
+  const requiredFields = ["name", "age", "type", "breed", "has_microchip"];
+  const missingFields = [];
+  requiredFields.forEach((field) => {
+    if (!newPet[field]) {
+      missingFields.push(field);
+    }
+  });
+  if (missingFields.length > 0) {
+    throw new MissingFieldsError(
+      `missing fields: ${missingFields.toString().replaceAll(",", ", ")}`
+    );
+  }
+
+  const pet = await addPet(newPet);
+  res.status(201).json({ pet });
+}
+
+async function deletePetController(req, res) {
+  const id = Number(req.params.id);
+
+  const found = await fetchPetById(id)
+  if (!found) {
+      throw new NoDataError(`no pet with id: ${id}`);
+  }
+
+  const pet = await deletePet(id);
+  res.status(201).json({ pet });
+}
+
+module.exports = {
+  getPetsController,
+  getPetsByIdController,
+  updatePetByIdController,
+  addPetController,
+  deletePetController,
+};
diff --git a/src/dal/bookRepository.js b/src/dal/bookRepository.js
new file mode 100644
index 00000000..93d08473
--- /dev/null
+++ b/src/dal/bookRepository.js
@@ -0,0 +1,101 @@
+const db = require("../../db/index.js");
+
+async function fetchAllBooks() {
+  try {
+    const result = await db.query("SELECT * FROM books");
+    return result.rows;
+  } catch (e) {
+    console.log(e);
+  }
+}
+
+async function fetchBookByQuery(query) {
+  let sqlQuery = "SELECT * FROM books";
+  const params = [];
+  const perPage = query.perPage || 20;
+
+  if (query.author) {
+    params.push(query.author);
+    sqlQuery += ` WHERE author = $${params.length}`;
+  }
+
+  params.push(perPage);
+  sqlQuery += ` LIMIT $${params.length}`;
+
+  if (query.page) {
+    params.push((query.page - 1) * query.perPage);
+    sqlQuery += ` OFFSET $${params.length}`;
+  }
+
+  try {
+    const result = await db.query(sqlQuery, params);
+    return result.rows;
+  } catch (e) {
+    console.log(e);
+  }
+}
+
+async function postBook(book) {
+  try {
+    const sqlQuery = `INSERT INTO books (title, type, author, topic, publication_date, pages) VALUES ($1, $2, $3, $4, $5, $6) RETURNING *;`;
+    const result = await db.query(sqlQuery, [
+      book.title,
+      book.type,
+      book.author,
+      book.topic,
+      book.publication_date,
+      book.pages,
+    ]);
+    return result.rows[0];
+  } catch (e) {
+    console.log(e);
+  }
+}
+
+async function fetchBookById(id) {
+  try {
+    const sqlQuery = "SELECT * FROM books WHERE id = $1;";
+    const result = await db.query(sqlQuery, [id]);
+    return result.rows[0];
+  } catch (e) {
+    console.log(e);
+  }
+}
+
+async function updateBookById(id, newParams) {
+  try {
+    const sqlQuery =
+      "UPDATE books SET title = $2, type = $3, author = $4, topic = $5, publication_date = $6, pages = $7 WHERE id = $1 RETURNING *;";
+    const result = await db.query(sqlQuery, [
+      id,
+      newParams.title,
+      newParams.type,
+      newParams.author,
+      newParams.topic,
+      newParams.publication_date,
+      newParams.pages,
+    ]);
+    return result.rows[0];
+  } catch (e) {
+    console.log(e);
+  }
+}
+
+async function deleteBookById(id) {
+  try {
+    const sqlQuery = "DELETE FROM books WHERE id = $1 RETURNING *;";
+    const result = await db.query(sqlQuery, [id]);
+    return result.rows[0];
+  } catch (e) {
+    console.log(e);
+  }
+}
+
+module.exports = {
+  fetchAllBooks,
+  postBook,
+  fetchBookById,
+  updateBookById,
+  deleteBookById,
+  fetchBookByQuery,
+};
diff --git a/src/dal/breedsRepository.js b/src/dal/breedsRepository.js
new file mode 100644
index 00000000..d9888489
--- /dev/null
+++ b/src/dal/breedsRepository.js
@@ -0,0 +1,10 @@
+const db = require("../../db/index.js");
+
+async function fetchBreeds(query) {
+
+    sqlQuery = 'SELECT breed FROM pets WHERE type = $1 GROUP BY breed'
+    const result = await db.query(sqlQuery, [query.type])
+    return result.rows
+}
+
+module.exports = { fetchBreeds }
\ No newline at end of file
diff --git a/src/dal/petsRepository.js b/src/dal/petsRepository.js
new file mode 100644
index 00000000..00caa6fe
--- /dev/null
+++ b/src/dal/petsRepository.js
@@ -0,0 +1,100 @@
+const db = require("../../db/index.js");
+
+async function fetchAllPets() {
+  const sqlQuery = "SELECT * FROM pets LIMIT 20";
+
+  try {
+    const pets = await db.query(sqlQuery);
+    return pets.rows;
+  } catch (e) {
+    console.log(e);
+  }
+}
+
+async function fetchPetsWithQuery(query) {
+  let sqlQuery = `SELECT * FROM pets`;
+  const params = [];
+  const perPage = query.perPage || 20;
+
+  params.push(perPage);
+  sqlQuery += ` LIMIT $${params.length}`;
+
+  if (query.page) {
+    params.push((query.page - 1) * query.perPage);
+    sqlQuery += ` OFFSET $${params.length}`;
+  }
+
+  try {
+    const result = await db.query(sqlQuery, params);
+    return result.rows;
+  } catch (e) {
+    console.log(e);
+  }
+}
+
+async function fetchPetById(id) {
+  const sqlQuery = "SELECT * FROM pets WHERE id = $1";
+
+  try {
+    const pets = await db.query(sqlQuery, [id]);
+    return pets.rows[0];
+  } catch (e) {
+    console.log(e);
+  }
+}
+
+async function updatePetById(id, updatedParams) {
+  const sqlQuery =
+    "UPDATE pets SET name = $1, age = $2, type = $3, breed = $4, has_microchip = $5 RETURNING *;";
+
+  try {
+    const result = await db.query(sqlQuery, [
+      updatedParams.name,
+      updatedParams.age,
+      updatedParams.type,
+      updatedParams.breed,
+      updatedParams.has_microchip,
+    ]);
+    return result.rows[0];
+  } catch (e) {
+    console.log(e);
+  }
+}
+
+async function addPet(newPet) {
+  const sqlQuery =
+    "INSERT INTO pets (name, age, type, breed, has_microchip) VALUES ($1, $2, $3, $4, $5) RETURNING *";
+
+  try {
+    const result = await db.query(sqlQuery, [
+      newPet.name,
+      newPet.age,
+      newPet.type,
+      newPet.breed,
+      newPet.has_microchip,
+    ]);
+    return result.rows[0];
+  } catch (e) {
+    console.log(e);
+  }
+}
+
+async function deletePet(petId) {
+  const sqlQuery = "DELETE FROM pets WHERE id = $1 RETURNING *";
+
+  try {
+    const result = await db.query(sqlQuery, [petId]);
+    return result.rows[0];
+  } catch (e) {
+    console.log(e);
+  }
+}
+
+module.exports = {
+  fetchAllPets,
+  fetchPetById,
+  updatePetById,
+  addPet,
+  deletePet,
+  fetchPetsWithQuery,
+};
diff --git a/src/errors/errors.js b/src/errors/errors.js
new file mode 100644
index 00000000..09d80724
--- /dev/null
+++ b/src/errors/errors.js
@@ -0,0 +1,16 @@
+class MissingFieldsError extends Error {
+}
+
+class NoDataError extends Error {
+
+}
+
+class InvalidParameterError extends Error {
+
+}
+
+class DataAlreadyExistsError extends Error {
+
+}
+
+module.exports = { MissingFieldsError, NoDataError, InvalidParameterError, DataAlreadyExistsError }
\ No newline at end of file
diff --git a/src/routers/books.js b/src/routers/books.js
index 1551dd87..23971ba9 100644
--- a/src/routers/books.js
+++ b/src/routers/books.js
@@ -1,9 +1,16 @@
 const express = require('express')
 const router = express.Router()
-const db = require("../../db");
 
-router.get('/', async (req, res) => {
+const { addBookController, getBooksController, getBookByIdController, putBookByIdController, deleteBookByIdController } = require('../controllers/booksControllers')
 
-})
+router.get('/', getBooksController)
+
+router.post('/', addBookController)
+
+router.get('/:id', getBookByIdController)
+
+router.put('/:id', putBookByIdController)
+
+router.delete('/:id', deleteBookByIdController)
 
 module.exports = router
diff --git a/src/routers/breeds.js b/src/routers/breeds.js
new file mode 100644
index 00000000..c27834ee
--- /dev/null
+++ b/src/routers/breeds.js
@@ -0,0 +1,8 @@
+const express = require('express')
+const router = express.Router()
+
+const { getAllBreedsController } = require('../controllers/breedsControllers')
+
+router.use('/', getAllBreedsController)
+
+module.exports = router
\ No newline at end of file
diff --git a/src/routers/pets.js b/src/routers/pets.js
new file mode 100644
index 00000000..56930e62
--- /dev/null
+++ b/src/routers/pets.js
@@ -0,0 +1,16 @@
+const express = require('express')
+const router = express.Router()
+
+const { getPetsController, getPetsByIdController, updatePetByIdController, addPetController, deletePetController } = require('../controllers/petsControllers')
+
+router.get('/', getPetsController)
+
+router.get('/:id', getPetsByIdController)
+
+router.put('/:id', updatePetByIdController)
+
+router.post('/', addPetController)
+
+router.delete('/:id', deletePetController)
+
+module.exports = router 
\ No newline at end of file
diff --git a/src/server.js b/src/server.js
index dac55e5d..24a3fc33 100644
--- a/src/server.js
+++ b/src/server.js
@@ -1,3 +1,5 @@
+require('dotenv').config()
+require('express-async-errors')
 const express = require("express");
 const morgan = require("morgan");
 const cors = require("cors");
@@ -10,7 +12,34 @@ app.use(express.json());
 
 //TODO: Implement books and pets APIs using Express Modular Routers
 const booksRouter = require('./routers/books.js')
-
+const petsRouter = require('./routers/pets.js')
+const breedsRouter = require('./routers/breeds.js')
 app.use('/books', booksRouter)
+app.use('/pets', petsRouter)
+app.use('/breeds', breedsRouter)
+
+//Error handling
+const { MissingFieldsError, NoDataError, InvalidParameterError, DataAlreadyExistsError } = require('./errors/errors.js')
+
+app.use((error, req, res, next) => {
+    if (error instanceof MissingFieldsError) {
+        return res.status(400).json({error: error.message})
+    }
+    if (error instanceof NoDataError) {
+        return res.status(404).json({error: error.message})
+    }
+
+    if (error instanceof InvalidParameterError) {
+        return res.status(400).json({error: error.message})
+    }
+
+    if (error instanceof DataAlreadyExistsError) {
+        return res.status(409).json({error: error.message})
+    }
+    console.log(`Unhandled error`, error)
+    res.status(500).json({
+        message: 'Something went wrong'
+    })
+})
 
 module.exports = app
diff --git a/utils/dbConnection.js b/utils/dbConnection.js
new file mode 100644
index 00000000..28dc327d
--- /dev/null
+++ b/utils/dbConnection.js
@@ -0,0 +1,16 @@
+const { Pool } = require('pg');
+
+const { PGHOST, PGDATABASE, PGUSER, PGPASSWORD } = process.env;
+
+const dbConnection = new Pool({
+  host: PGHOST,
+  database: PGDATABASE,
+  username: PGUSER,
+  password: PGPASSWORD,
+  port: 5432, 
+  ssl: {
+    require: true,
+  },
+})
+
+module.exports = dbConnection
\ No newline at end of file