diff --git a/async_db/src/db.rs b/async_db/src/db.rs
index 252f55c..d7c7692 100644
--- a/async_db/src/db.rs
+++ b/async_db/src/db.rs
@@ -1,8 +1,6 @@
 use actix_web::{web, Error as AWError};
 use failure::Error;
 use futures::{Future, TryFutureExt};
-use r2d2;
-use r2d2_sqlite;
 use rusqlite::{Statement, NO_PARAMS};
 use serde::{Deserialize, Serialize};
 use std::{thread::sleep, time::Duration};
diff --git a/async_db/src/main.rs b/async_db/src/main.rs
index 90a5956..66f368f 100644
--- a/async_db/src/main.rs
+++ b/async_db/src/main.rs
@@ -22,6 +22,7 @@ mod db;
 use db::{Pool, Queries};
 
 /// Version 1: Calls 4 queries in sequential order, as an asynchronous handler
+#[allow(clippy::eval_order_dependence)] // it's FP?
 async fn asyncio_weather(db: web::Data<Pool>) -> Result<HttpResponse, AWError> {
     let result = vec![
         db::execute(&db, Queries::GetTopTenHottestYears).await?,
diff --git a/async_ex2/src/handlers/parts.rs b/async_ex2/src/handlers/parts.rs
index 9e8725b..734931a 100644
--- a/async_ex2/src/handlers/parts.rs
+++ b/async_ex2/src/handlers/parts.rs
@@ -2,18 +2,18 @@ use actix_web::{web, Error, HttpResponse};
 
 use crate::common::{Part, Product};
 
-pub async fn get_parts(query: web::Query<Option<Part>>) -> Result<HttpResponse, Error> {
+pub async fn get_parts(_query: web::Query<Option<Part>>) -> Result<HttpResponse, Error> {
     Ok(HttpResponse::Ok().finish())
 }
 
-pub async fn add_part(new_part: web::Json<Product>) -> Result<HttpResponse, Error> {
+pub async fn add_part(_new_part: web::Json<Product>) -> Result<HttpResponse, Error> {
     Ok(HttpResponse::Ok().finish())
 }
 
-pub async fn get_part_detail(id: web::Path<String>) -> Result<HttpResponse, Error> {
+pub async fn get_part_detail(_id: web::Path<String>) -> Result<HttpResponse, Error> {
     Ok(HttpResponse::Ok().finish())
 }
 
-pub async fn remove_part(id: web::Path<String>) -> Result<HttpResponse, Error> {
+pub async fn remove_part(_id: web::Path<String>) -> Result<HttpResponse, Error> {
     Ok(HttpResponse::Ok().finish())
 }
diff --git a/async_ex2/src/handlers/products.rs b/async_ex2/src/handlers/products.rs
index 624b820..7f65fd6 100644
--- a/async_ex2/src/handlers/products.rs
+++ b/async_ex2/src/handlers/products.rs
@@ -3,22 +3,22 @@ use actix_web::{web, Error, HttpResponse};
 use crate::common::{Part, Product};
 
 pub async fn get_products(
-    query: web::Query<Option<Part>>,
+    _query: web::Query<Option<Part>>,
 ) -> Result<HttpResponse, Error> {
     Ok(HttpResponse::Ok().finish())
 }
 
 pub async fn add_product(
-    new_product: web::Json<Product>,
+    _new_product: web::Json<Product>,
 ) -> Result<HttpResponse, Error> {
     Ok(HttpResponse::Ok().finish())
 }
 
-pub async fn get_product_detail(id: web::Path<String>) -> Result<HttpResponse, Error> {
+pub async fn get_product_detail(_id: web::Path<String>) -> Result<HttpResponse, Error> {
     Ok(HttpResponse::Ok().finish())
 }
 
-pub async fn remove_product(id: web::Path<String>) -> Result<HttpResponse, Error> {
+pub async fn remove_product(_id: web::Path<String>) -> Result<HttpResponse, Error> {
     Ok(HttpResponse::Ok().finish())
 }
 
diff --git a/async_pg/src/main.rs b/async_pg/src/main.rs
index 8d48c68..ad3dc98 100644
--- a/async_pg/src/main.rs
+++ b/async_pg/src/main.rs
@@ -99,7 +99,7 @@ mod handlers {
         let user_info: User = user.into_inner();
 
         let client: Client =
-            db_pool.get().await.map_err(|err| MyError::PoolError(err))?;
+            db_pool.get().await.map_err(MyError::PoolError)?;
 
         let new_user = db::add_user(&client, user_info).await?;
 
diff --git a/awc_https/src/main.rs b/awc_https/src/main.rs
index 7415c94..2958ea9 100644
--- a/awc_https/src/main.rs
+++ b/awc_https/src/main.rs
@@ -2,7 +2,7 @@ use actix_web::{web, App, HttpRequest, HttpResponse, HttpServer, client::{Client
 use openssl::ssl::{SslConnector, SslMethod};
 
 
-async fn index(req: HttpRequest) -> HttpResponse {
+async fn index(_req: HttpRequest) -> HttpResponse {
 	let builder = SslConnector::builder(SslMethod::tls()).unwrap();
 
     let client = Client::build()
diff --git a/docker_sample/src/main.rs b/docker_sample/src/main.rs
index 803e0b6..af38893 100644
--- a/docker_sample/src/main.rs
+++ b/docker_sample/src/main.rs
@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate actix_web;
 
-use actix_web::{web, App, HttpResponse, HttpServer, Responder};
+use actix_web::{App, HttpResponse, HttpServer, Responder};
 
 #[get("/")]
 async fn index() -> impl Responder {
diff --git a/graphql-demo/src/db.rs b/graphql-demo/src/db.rs
index 7924fce..e0983dd 100644
--- a/graphql-demo/src/db.rs
+++ b/graphql-demo/src/db.rs
@@ -1,4 +1,3 @@
-use r2d2;
 use r2d2_mysql::mysql::{Opts, OptsBuilder};
 use r2d2_mysql::MysqlConnectionManager;
 
diff --git a/graphql-demo/src/schemas/product.rs b/graphql-demo/src/schemas/product.rs
index 0fe3744..9304ff3 100644
--- a/graphql-demo/src/schemas/product.rs
+++ b/graphql-demo/src/schemas/product.rs
@@ -1,4 +1,3 @@
-use juniper;
 use mysql::{from_row, params, Error as DBError, Row};
 
 use crate::schemas::root::Context;
diff --git a/graphql-demo/src/schemas/root.rs b/graphql-demo/src/schemas/root.rs
index ad3e890..051ef49 100644
--- a/graphql-demo/src/schemas/root.rs
+++ b/graphql-demo/src/schemas/root.rs
@@ -1,4 +1,3 @@
-use juniper;
 use juniper::{FieldError, FieldResult, RootNode};
 use mysql::{from_row, params, Error as DBError, Row};
 
@@ -109,9 +108,9 @@ impl MutationRoot {
         let insert: Result<Option<Row>, DBError> = conn.first_exec(
             "INSERT INTO user(id, name, email) VALUES(:id, :name, :email)",
             params! {
-                "id" => &new_id.to_owned(),
-                "name" => &user.name.to_owned(),
-                "email" => &user.email.to_owned(),
+                "id" => &new_id,
+                "name" => &user.name,
+                "email" => &user.email,
             },
         );
 
@@ -141,9 +140,9 @@ impl MutationRoot {
         let insert: Result<Option<Row>, DBError> = conn.first_exec(
             "INSERT INTO product(id, user_id, name, price) VALUES(:id, :user_id, :name, :price)",
             params! {
-                "id" => &new_id.to_owned(),
-                "user_id" => &product.user_id.to_owned(),
-                "name" => &product.name.to_owned(),
+                "id" => &new_id,
+                "user_id" => &product.user_id,
+                "name" => &product.name,
                 "price" => &product.price.to_owned(),
             },
         );
diff --git a/graphql-demo/src/schemas/user.rs b/graphql-demo/src/schemas/user.rs
index 4d71ae8..69ed3dc 100644
--- a/graphql-demo/src/schemas/user.rs
+++ b/graphql-demo/src/schemas/user.rs
@@ -1,4 +1,3 @@
-use juniper;
 use mysql::{from_row, params};
 
 use crate::schemas::product::Product;
@@ -33,7 +32,8 @@ impl User {
 
     fn products(&self, context: &Context) -> Vec<Product> {
         let mut conn = context.dbpool.get().unwrap();
-        let products = conn
+
+        conn
             .prep_exec(
                 "select * from product where user_id=:user_id",
                 params! {
@@ -54,7 +54,6 @@ impl User {
                     })
                     .collect()
             })
-            .unwrap();
-        products
+            .unwrap()
     }
 }
diff --git a/jsonrpc/src/main.rs b/jsonrpc/src/main.rs
index da0f1db..c2c5644 100644
--- a/jsonrpc/src/main.rs
+++ b/jsonrpc/src/main.rs
@@ -1,3 +1,6 @@
+// Allow this lint since it's fine to use type directly in the short example.
+#![allow(clippy::type_complexity)]
+
 use std::error;
 use std::pin::Pin;
 use std::sync::{Arc, RwLock};
@@ -7,7 +10,6 @@ use actix_rt::time::delay_for;
 use actix_web::{middleware, web, App, Error, HttpResponse, HttpServer};
 use bytes::Bytes;
 use futures::{Future, FutureExt};
-use serde_json;
 use serde_json::Value;
 
 #[allow(dead_code)]
diff --git a/middleware/src/main.rs b/middleware/src/main.rs
index c2237be..de3a1b7 100644
--- a/middleware/src/main.rs
+++ b/middleware/src/main.rs
@@ -1,3 +1,5 @@
+#![allow(clippy::type_complexity)]
+
 use actix_service::Service;
 use actix_web::{web, App, HttpServer};
 use futures::future::FutureExt;
diff --git a/r2d2/src/main.rs b/r2d2/src/main.rs
index 25e89ae..4cbbb24 100644
--- a/r2d2/src/main.rs
+++ b/r2d2/src/main.rs
@@ -4,7 +4,6 @@ use std::io;
 use actix_web::{middleware, web, App, Error, HttpResponse, HttpServer};
 use r2d2::Pool;
 use r2d2_sqlite::SqliteConnectionManager;
-use uuid;
 
 /// Async request handler. Ddb pool is stored in application state.
 async fn index(
diff --git a/server-sent-events/src/main.rs b/server-sent-events/src/main.rs
index bbfc51d..3c3d858 100644
--- a/server-sent-events/src/main.rs
+++ b/server-sent-events/src/main.rs
@@ -5,7 +5,6 @@ use std::time::Duration;
 
 use actix_web::web::{Bytes, Data, Path};
 use actix_web::{web, App, Error, HttpResponse, HttpServer, Responder};
-use env_logger;
 use futures::{Stream, StreamExt};
 use tokio::sync::mpsc::{channel, Receiver, Sender};
 use tokio::time::{interval_at, Instant};
diff --git a/shutdown-server/src/main.rs b/shutdown-server/src/main.rs
index b051a57..6356c20 100644
--- a/shutdown-server/src/main.rs
+++ b/shutdown-server/src/main.rs
@@ -23,7 +23,7 @@ async fn main() -> std::io::Result<()> {
 
     // create a channel
     let (tx, rx) = mpsc::channel::<()>();
-    let stopper = tx.clone();
+    let _stopper = tx.clone();
 
     let bind = "127.0.0.1:8080";
 
diff --git a/state/src/main.rs b/state/src/main.rs
index 29b9a9d..cad3a57 100644
--- a/state/src/main.rs
+++ b/state/src/main.rs
@@ -54,6 +54,7 @@ async fn main() -> io::Result<()> {
     env_logger::init();
 
     // Create some global state prior to building the server
+    #[allow(clippy::mutex_atomic)] // it's intentional.
     let counter1 = web::Data::new(Mutex::new(0usize));
     let counter3 = web::Data::new(AtomicUsize::new(0usize));
 
diff --git a/todo/src/api.rs b/todo/src/api.rs
index 344fbb4..f70e06f 100644
--- a/todo/src/api.rs
+++ b/todo/src/api.rs
@@ -27,7 +27,7 @@ pub async fn index(
 
     let rendered = tmpl
         .render("index.html.tera", &context)
-        .map_err(|e| error::ErrorInternalServerError(e))?;
+        .map_err(error::ErrorInternalServerError)?;
 
     Ok(HttpResponse::Ok().body(rendered))
 }
diff --git a/todo/src/model.rs b/todo/src/model.rs
index 2c8c03a..6fa1dc2 100644
--- a/todo/src/model.rs
+++ b/todo/src/model.rs
@@ -1,4 +1,3 @@
-use diesel;
 use diesel::pg::PgConnection;
 use diesel::prelude::*;
 use serde::Serialize;