diff --git a/CHANGES.md b/CHANGES.md
index 0077cd518..f0b55801b 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -2,25 +2,31 @@
 
 ## Unreleased - 2021-xx-xx
 ### Added
-* `Compat` middleware enabling generic response body/error type of middlewares
-  like `Logger` and `Compress` to be used in `middleware::Condition` 
-  and `Resource`, `Scope` services. [#1865]
+* `Compat` middleware enabling generic response body/error type of middlewares like `Logger` and
+  `Compress` to be used in `middleware::Condition` and `Resource`, `Scope` services. [#1865]
 
 ### Changed
 * Update `actix-*` dependencies to tokio `1.0` based versions. [#1813]
 * Bumped `rand` to `0.8`.
 * Update `rust-tls` to `0.19`. [#1813]
 * Rename `Handler` to `HandlerService` and rename `Factory` to `Handler`. [#1852]
+* The default `TrailingSlash` is now `Trim`, in line with existing documentation. See migration
+  guide for implications. [#1875]
+* Rename `DefaultHeaders::{content_type => add_content_type}`. [#1875]
 * MSRV is now 1.46.0.
 
-[#1813]: https://github.com/actix/actix-web/pull/1813
-[#1865]: https://github.com/actix/actix-web/pull/1865
-
 ### Fixed
-* added the actual parsing error to `test::read_body_json` [#1812]
+* Added the underlying parse error to `test::read_body_json`'s panic message. [#1812]
+
+### Removed
+* Public modules `middleware::{normalize, err_handlers}`. All necessary middleware structs are now
+  exposed directly by the `middleware` module.
 
 [#1812]: https://github.com/actix/actix-web/pull/1812
+[#1813]: https://github.com/actix/actix-web/pull/1813
 [#1852]: https://github.com/actix/actix-web/pull/1852
+[#1865]: https://github.com/actix/actix-web/pull/1865
+[#1875]: https://github.com/actix/actix-web/pull/1875
 
 
 ## 3.3.2 - 2020-12-01
diff --git a/MIGRATION.md b/MIGRATION.md
index 5c4650194..e01702868 100644
--- a/MIGRATION.md
+++ b/MIGRATION.md
@@ -1,5 +1,15 @@
 ## Unreleased
 
+* The default `NormalizePath` behavior now strips trailing slashes by default. This was
+  previously documented to be the case in v3 but the behavior now matches. The effect is that
+  routes defined with trailing slashes will become inaccessible when
+  using `NormalizePath::default()`.
+  
+  Before: `#[get("/test/")`  
+  After: `#[get("/test")`  
+
+  Alternatively, explicitly require trailing slashes: `NormalizePath::new(TrailingSlash::Always)`.
+
 
 ## 3.0.0
 
diff --git a/examples/basic.rs b/examples/basic.rs
index 8b2bf2319..e8ad5fcdb 100644
--- a/examples/basic.rs
+++ b/examples/basic.rs
@@ -18,8 +18,7 @@ async fn no_params() -> &'static str {
 
 #[actix_web::main]
 async fn main() -> std::io::Result<()> {
-    std::env::set_var("RUST_LOG", "actix_server=info,actix_web=info");
-    env_logger::init();
+    env_logger::init_from_env(env_logger::Env::new().default_filter_or("info"));
 
     HttpServer::new(|| {
         App::new()
diff --git a/src/middleware/compat.rs b/src/middleware/compat.rs
index 66346b6d6..eabd1190d 100644
--- a/src/middleware/compat.rs
+++ b/src/middleware/compat.rs
@@ -1,41 +1,45 @@
-//! `Middleware` for enabling any middleware to be used in `Resource`, `Scope` and `Condition`.
-use std::future::Future;
-use std::pin::Pin;
-use std::task::{Context, Poll};
+//! For middleware documentation, see [`Compat`].
 
-use actix_http::body::Body;
-use actix_http::body::{MessageBody, ResponseBody};
+use std::{
+    future::Future,
+    pin::Pin,
+    task::{Context, Poll},
+};
+
+use actix_http::body::{Body, MessageBody, ResponseBody};
 use actix_service::{Service, Transform};
-use futures_core::future::LocalBoxFuture;
-use futures_core::ready;
+use futures_core::{future::LocalBoxFuture, ready};
 
-use crate::error::Error;
-use crate::service::ServiceResponse;
+use crate::{error::Error, service::ServiceResponse};
 
-/// `Middleware` for enabling any middleware to be used in `Resource`, `Scope` and `Condition`.
-///
-///
-/// ## Usage
+/// Middleware for enabling any middleware to be used in [`Resource::wrap`](crate::Resource::wrap),
+/// [`Scope::wrap`](crate::Scope::wrap) and [`Condition`](super::Condition).
 ///
+/// # Usage
 /// ```rust
 /// use actix_web::middleware::{Logger, Compat};
 /// use actix_web::{App, web};
 ///
 /// let logger = Logger::default();
 ///
-/// // this would not compile
-/// // let app = App::new().service(web::scope("scoped").wrap(logger));
+/// // this would not compile because of incompatible body types
+/// // let app = App::new()
+/// //     .service(web::scope("scoped").wrap(logger));
 ///
-/// // by using scoped middleware we can use logger in scope.
-/// let app = App::new().service(web::scope("scoped").wrap(Compat::new(logger)));
+/// // by using this middleware we can use the logger on a scope
+/// let app = App::new()
+///     .service(web::scope("scoped").wrap(Compat::new(logger)));
 /// ```
 pub struct Compat<T> {
     transform: T,
 }
 
 impl<T> Compat<T> {
-    pub fn new(transform: T) -> Self {
-        Self { transform }
+    /// Wrap a middleware to give it broader compatibility.
+    pub fn new(middleware: T) -> Self {
+        Self {
+            transform: middleware,
+        }
     }
 }
 
diff --git a/src/middleware/compress.rs b/src/middleware/compress.rs
index b6ad2c4b5..376719ab2 100644
--- a/src/middleware/compress.rs
+++ b/src/middleware/compress.rs
@@ -1,45 +1,47 @@
-//! `Middleware` for compressing response body.
-use std::cmp;
-use std::future::Future;
-use std::marker::PhantomData;
-use std::pin::Pin;
-use std::str::FromStr;
-use std::task::{Context, Poll};
+//! For middleware documentation, see [`Compress`].
 
-use actix_http::body::MessageBody;
-use actix_http::encoding::Encoder;
-use actix_http::http::header::{ContentEncoding, ACCEPT_ENCODING};
-use actix_http::Error;
+use std::{
+    cmp,
+    future::Future,
+    marker::PhantomData,
+    pin::Pin,
+    str::FromStr,
+    task::{Context, Poll},
+};
+
+use actix_http::{
+    body::MessageBody,
+    encoding::Encoder,
+    http::header::{ContentEncoding, ACCEPT_ENCODING},
+    Error,
+};
 use actix_service::{Service, Transform};
 use futures_util::future::{ok, Ready};
 use pin_project::pin_project;
 
-use crate::dev::BodyEncoding;
-use crate::service::{ServiceRequest, ServiceResponse};
+use crate::{
+    dev::BodyEncoding,
+    service::{ServiceRequest, ServiceResponse},
+};
 
-#[derive(Debug, Clone)]
-/// `Middleware` for compressing response body.
+/// Middleware for compressing response payloads.
 ///
-/// Use `BodyEncoding` trait for overriding response compression.
-/// To disable compression set encoding to `ContentEncoding::Identity` value.
+/// Use `BodyEncoding` trait for overriding response compression. To disable compression set
+/// encoding to `ContentEncoding::Identity`.
 ///
+/// # Usage
 /// ```rust
 /// use actix_web::{web, middleware, App, HttpResponse};
 ///
-/// fn main() {
-///     let app = App::new()
-///         .wrap(middleware::Compress::default())
-///         .service(
-///             web::resource("/test")
-///                 .route(web::get().to(|| HttpResponse::Ok()))
-///                 .route(web::head().to(|| HttpResponse::MethodNotAllowed()))
-///         );
-/// }
+/// let app = App::new()
+///     .wrap(middleware::Compress::default())
+///     .default_service(web::to(|| HttpResponse::NotFound()));
 /// ```
+#[derive(Debug, Clone)]
 pub struct Compress(ContentEncoding);
 
 impl Compress {
-    /// Create new `Compress` middleware with default encoding.
+    /// Create new `Compress` middleware with the specified encoding.
     pub fn new(encoding: ContentEncoding) -> Self {
         Compress(encoding)
     }
@@ -84,9 +86,7 @@ where
     type Error = Error;
     type Future = CompressResponse<S, B>;
 
-    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
-        self.service.poll_ready(cx)
-    }
+    actix_service::forward_ready!(service);
 
     #[allow(clippy::borrow_interior_mutable_const)]
     fn call(&mut self, req: ServiceRequest) -> Self::Future {
@@ -109,7 +109,6 @@ where
     }
 }
 
-#[doc(hidden)]
 #[pin_project]
 pub struct CompressResponse<S, B>
 where
diff --git a/src/middleware/condition.rs b/src/middleware/condition.rs
index 04173e053..d61e7d576 100644
--- a/src/middleware/condition.rs
+++ b/src/middleware/condition.rs
@@ -1,35 +1,36 @@
-//! `Middleware` for conditionally enables another middleware.
+//! For middleware documentation, see [`Condition`].
+
 use std::task::{Context, Poll};
 
 use actix_service::{Service, Transform};
-use futures_util::future::{ok, Either, FutureExt, LocalBoxFuture};
+use futures_util::future::{Either, FutureExt, LocalBoxFuture};
 
-/// `Middleware` for conditionally enables another middleware.
-/// The controlled middleware must not change the `Service` interfaces.
+/// Middleware for conditionally enabling other middleware.
 ///
-/// This means you cannot control such middlewares like `Logger` or `Compress` directly.
-/// *. See `Compat` middleware for alternative.
-///
-/// ## Usage
+/// The controlled middleware must not change the `Service` interfaces. This means you cannot
+/// control such middlewares like `Logger` or `Compress` directly. See the [`Compat`](super::Compat)
+/// middleware for a workaround.
 ///
+/// # Usage
 /// ```rust
 /// use actix_web::middleware::{Condition, NormalizePath};
 /// use actix_web::App;
 ///
-/// # fn main() {
-/// let enable_normalize = std::env::var("NORMALIZE_PATH") == Ok("true".into());
+/// let enable_normalize = std::env::var("NORMALIZE_PATH").is_ok();
 /// let app = App::new()
 ///     .wrap(Condition::new(enable_normalize, NormalizePath::default()));
-/// # }
 /// ```
 pub struct Condition<T> {
-    trans: T,
+    transformer: T,
     enable: bool,
 }
 
 impl<T> Condition<T> {
-    pub fn new(enable: bool, trans: T) -> Self {
-        Self { trans, enable }
+    pub fn new(enable: bool, transformer: T) -> Self {
+        Self {
+            transformer,
+            enable,
+        }
     }
 }
 
@@ -49,16 +50,15 @@ where
 
     fn new_transform(&self, service: S) -> Self::Future {
         if self.enable {
-            let f = self.trans.new_transform(service).map(|res| {
-                res.map(
-                    ConditionMiddleware::Enable as fn(T::Transform) -> Self::Transform,
-                )
-            });
-            Either::Left(f)
+            let fut = self.transformer.new_transform(service);
+            async move {
+                let wrapped_svc = fut.await?;
+                Ok(ConditionMiddleware::Enable(wrapped_svc))
+            }
+            .boxed_local()
         } else {
-            Either::Right(ok(ConditionMiddleware::Disable(service)))
+            async move { Ok(ConditionMiddleware::Disable(service)) }.boxed_local()
         }
-        .boxed_local()
     }
 }
 
@@ -77,18 +77,16 @@ where
     type Future = Either<E::Future, D::Future>;
 
     fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
-        use ConditionMiddleware::*;
         match self {
-            Enable(service) => service.poll_ready(cx),
-            Disable(service) => service.poll_ready(cx),
+            ConditionMiddleware::Enable(service) => service.poll_ready(cx),
+            ConditionMiddleware::Disable(service) => service.poll_ready(cx),
         }
     }
 
     fn call(&mut self, req: Req) -> Self::Future {
-        use ConditionMiddleware::*;
         match self {
-            Enable(service) => Either::Left(service.call(req)),
-            Disable(service) => Either::Right(service.call(req)),
+            ConditionMiddleware::Enable(service) => Either::Left(service.call(req)),
+            ConditionMiddleware::Disable(service) => Either::Right(service.call(req)),
         }
     }
 }
@@ -96,14 +94,17 @@ where
 #[cfg(test)]
 mod tests {
     use actix_service::IntoService;
+    use futures_util::future::ok;
 
     use super::*;
-    use crate::dev::{ServiceRequest, ServiceResponse};
-    use crate::error::Result;
-    use crate::http::{header::CONTENT_TYPE, HeaderValue, StatusCode};
-    use crate::middleware::errhandlers::*;
-    use crate::test::{self, TestRequest};
-    use crate::HttpResponse;
+    use crate::{
+        dev::{ServiceRequest, ServiceResponse},
+        error::Result,
+        http::{header::CONTENT_TYPE, HeaderValue, StatusCode},
+        middleware::err_handlers::*,
+        test::{self, TestRequest},
+        HttpResponse,
+    };
 
     #[allow(clippy::unnecessary_wraps)]
     fn render_500<B>(mut res: ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> {
diff --git a/src/middleware/defaultheaders.rs b/src/middleware/default_headers.rs
similarity index 79%
rename from src/middleware/defaultheaders.rs
rename to src/middleware/default_headers.rs
index d648ad70f..6f027124f 100644
--- a/src/middleware/defaultheaders.rs
+++ b/src/middleware/default_headers.rs
@@ -1,24 +1,34 @@
-//! Middleware for setting default response headers
-use std::convert::TryFrom;
-use std::future::Future;
-use std::marker::PhantomData;
-use std::pin::Pin;
-use std::rc::Rc;
-use std::task::{Context, Poll};
+//! For middleware documentation, see [`DefaultHeaders`].
 
-use actix_service::{Service, Transform};
-use futures_util::future::{ready, Ready};
-use futures_util::ready;
+use std::{
+    convert::TryFrom,
+    future::Future,
+    marker::PhantomData,
+    pin::Pin,
+    rc::Rc,
+    task::{Context, Poll},
+};
 
-use crate::http::header::{HeaderName, HeaderValue, CONTENT_TYPE};
-use crate::http::{Error as HttpError, HeaderMap};
-use crate::service::{ServiceRequest, ServiceResponse};
-use crate::Error;
+use futures_util::{
+    future::{ready, Ready},
+    ready,
+};
 
-/// `Middleware` for setting default response headers.
+use crate::{
+    dev::{Service, Transform},
+    http::{
+        header::{HeaderName, HeaderValue, CONTENT_TYPE},
+        Error as HttpError, HeaderMap,
+    },
+    service::{ServiceRequest, ServiceResponse},
+    Error,
+};
+
+/// Middleware for setting default response headers.
 ///
-/// This middleware does not set header if response headers already contains it.
+/// Headers with the same key that are already set in a response will *not* be overwritten.
 ///
+/// # Usage
 /// ```rust
 /// use actix_web::{web, http, middleware, App, HttpResponse};
 ///
@@ -38,7 +48,6 @@ pub struct DefaultHeaders {
 }
 
 struct Inner {
-    ct: bool,
     headers: HeaderMap,
 }
 
@@ -46,7 +55,6 @@ impl Default for DefaultHeaders {
     fn default() -> Self {
         DefaultHeaders {
             inner: Rc::new(Inner {
-                ct: false,
                 headers: HeaderMap::new(),
             }),
         }
@@ -54,12 +62,12 @@ impl Default for DefaultHeaders {
 }
 
 impl DefaultHeaders {
-    /// Construct `DefaultHeaders` middleware.
+    /// Constructs an empty `DefaultHeaders` middleware.
     pub fn new() -> DefaultHeaders {
         DefaultHeaders::default()
     }
 
-    /// Set a header.
+    /// Adds a header to the default set.
     #[inline]
     pub fn header<K, V>(mut self, key: K, value: V) -> Self
     where
@@ -84,11 +92,18 @@ impl DefaultHeaders {
         self
     }
 
-    /// Set *CONTENT-TYPE* header if response does not contain this header.
-    pub fn content_type(mut self) -> Self {
+    /// Adds a default *Content-Type* header if response does not contain one.
+    ///
+    /// Default is `application/octet-stream`.
+    pub fn add_content_type(mut self) -> Self {
         Rc::get_mut(&mut self.inner)
-            .expect("Multiple copies exist")
-            .ct = true;
+            .expect("Multiple `Inner` copies exist.")
+            .headers
+            .insert(
+                CONTENT_TYPE,
+                HeaderValue::from_static("application/octet-stream"),
+            );
+
         self
     }
 }
@@ -126,9 +141,7 @@ where
     type Error = Error;
     type Future = DefaultHeaderFuture<S, B>;
 
-    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
-        self.service.poll_ready(cx)
-    }
+    actix_service::forward_ready!(service);
 
     fn call(&mut self, req: ServiceRequest) -> Self::Future {
         let inner = self.inner.clone();
@@ -160,19 +173,14 @@ where
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
         let this = self.project();
         let mut res = ready!(this.fut.poll(cx))?;
+
         // set response headers
         for (key, value) in this.inner.headers.iter() {
             if !res.headers().contains_key(key) {
                 res.headers_mut().insert(key.clone(), value.clone());
             }
         }
-        // default content-type
-        if this.inner.ct && !res.headers().contains_key(&CONTENT_TYPE) {
-            res.headers_mut().insert(
-                CONTENT_TYPE,
-                HeaderValue::from_static("application/octet-stream"),
-            );
-        }
+
         Poll::Ready(Ok(res))
     }
 }
@@ -183,10 +191,12 @@ mod tests {
     use futures_util::future::ok;
 
     use super::*;
-    use crate::dev::ServiceRequest;
-    use crate::http::header::CONTENT_TYPE;
-    use crate::test::{ok_service, TestRequest};
-    use crate::HttpResponse;
+    use crate::{
+        dev::ServiceRequest,
+        http::header::CONTENT_TYPE,
+        test::{ok_service, TestRequest},
+        HttpResponse,
+    };
 
     #[actix_rt::test]
     async fn test_default_headers() {
@@ -219,7 +229,7 @@ mod tests {
         let srv =
             |req: ServiceRequest| ok(req.into_response(HttpResponse::Ok().finish()));
         let mut mw = DefaultHeaders::new()
-            .content_type()
+            .add_content_type()
             .new_transform(srv.into_service())
             .await
             .unwrap();
diff --git a/src/middleware/errhandlers.rs b/src/middleware/err_handlers.rs
similarity index 85%
rename from src/middleware/errhandlers.rs
rename to src/middleware/err_handlers.rs
index 8503b3e1e..dfd9a7dc5 100644
--- a/src/middleware/errhandlers.rs
+++ b/src/middleware/err_handlers.rs
@@ -1,35 +1,36 @@
-//! Custom handlers service for responses.
+//! For middleware documentation, see [`ErrorHandlers`].
+
 use std::rc::Rc;
-use std::task::{Context, Poll};
 
 use actix_service::{Service, Transform};
 use ahash::AHashMap;
 use futures_util::future::{ok, FutureExt, LocalBoxFuture, Ready};
 
-use crate::dev::{ServiceRequest, ServiceResponse};
-use crate::error::{Error, Result};
-use crate::http::StatusCode;
+use crate::{
+    dev::{ServiceRequest, ServiceResponse},
+    error::{Error, Result},
+    http::StatusCode,
+};
 
-/// Error handler response
+/// Return type for [`ErrorHandlers`] custom handlers.
 pub enum ErrorHandlerResponse<B> {
-    /// New http response got generated
+    /// Immediate HTTP response.
     Response(ServiceResponse<B>),
-    /// Result is a future that resolves to a new http response
+
+    /// A future that resolves to an HTTP response.
     Future(LocalBoxFuture<'static, Result<ServiceResponse<B>, Error>>),
 }
 
 type ErrorHandler<B> = dyn Fn(ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>>;
 
-/// `Middleware` for allowing custom handlers for responses.
+/// Middleware for registering custom status code based error handlers.
 ///
-/// You can use `ErrorHandlers::handler()` method  to register a custom error
-/// handler for specific status code. You can modify existing response or
-/// create completely new one.
-///
-/// ## Example
+/// Register handlers with the `ErrorHandlers::handler()` method to register a custom error handler
+/// for a given status code. Handlers can modify existing responses or create completely new ones.
 ///
+/// # Usage
 /// ```rust
-/// use actix_web::middleware::errhandlers::{ErrorHandlers, ErrorHandlerResponse};
+/// use actix_web::middleware::{ErrorHandlers, ErrorHandlerResponse};
 /// use actix_web::{web, http, dev, App, HttpRequest, HttpResponse, Result};
 ///
 /// fn render_500<B>(mut res: dev::ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> {
@@ -39,7 +40,6 @@ type ErrorHandler<B> = dyn Fn(ServiceResponse<B>) -> Result<ErrorHandlerResponse
 ///     Ok(ErrorHandlerResponse::Response(res))
 /// }
 ///
-/// # fn main() {
 /// let app = App::new()
 ///     .wrap(
 ///         ErrorHandlers::new()
@@ -49,7 +49,6 @@ type ErrorHandler<B> = dyn Fn(ServiceResponse<B>) -> Result<ErrorHandlerResponse
 ///         .route(web::get().to(|| HttpResponse::Ok()))
 ///         .route(web::head().to(|| HttpResponse::MethodNotAllowed())
 ///     ));
-/// # }
 /// ```
 pub struct ErrorHandlers<B> {
     handlers: Rc<AHashMap<StatusCode, Box<ErrorHandler<B>>>>,
@@ -64,12 +63,12 @@ impl<B> Default for ErrorHandlers<B> {
 }
 
 impl<B> ErrorHandlers<B> {
-    /// Construct new `ErrorHandlers` instance
+    /// Construct new `ErrorHandlers` instance.
     pub fn new() -> Self {
         ErrorHandlers::default()
     }
 
-    /// Register error handler for specified status code
+    /// Register error handler for specified status code.
     pub fn handler<F>(mut self, status: StatusCode, handler: F) -> Self
     where
         F: Fn(ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> + 'static,
@@ -117,9 +116,7 @@ where
     type Error = Error;
     type Future = LocalBoxFuture<'static, Result<Self::Response, Self::Error>>;
 
-    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
-        self.service.poll_ready(cx)
-    }
+    actix_service::forward_ready!(service);
 
     fn call(&mut self, req: ServiceRequest) -> Self::Future {
         let handlers = self.handlers.clone();
diff --git a/src/middleware/logger.rs b/src/middleware/logger.rs
index c952aeac9..cdbd5e485 100644
--- a/src/middleware/logger.rs
+++ b/src/middleware/logger.rs
@@ -1,13 +1,16 @@
-//! Request logging middleware
-use std::collections::HashSet;
-use std::convert::TryFrom;
-use std::env;
-use std::fmt::{self, Display, Formatter};
-use std::future::Future;
-use std::marker::PhantomData;
-use std::pin::Pin;
-use std::rc::Rc;
-use std::task::{Context, Poll};
+//! For middleware documentation, see [`Logger`].
+
+use std::{
+    collections::HashSet,
+    convert::TryFrom,
+    env,
+    fmt::{self, Display as _},
+    future::Future,
+    marker::PhantomData,
+    pin::Pin,
+    rc::Rc,
+    task::{Context, Poll},
+};
 
 use actix_service::{Service, Transform};
 use bytes::Bytes;
@@ -16,78 +19,69 @@ use log::debug;
 use regex::{Regex, RegexSet};
 use time::OffsetDateTime;
 
-use crate::dev::{BodySize, MessageBody, ResponseBody};
-use crate::error::{Error, Result};
-use crate::http::{HeaderName, StatusCode};
-use crate::service::{ServiceRequest, ServiceResponse};
-use crate::HttpResponse;
+use crate::{
+    dev::{BodySize, MessageBody, ResponseBody},
+    error::{Error, Result},
+    http::{HeaderName, StatusCode},
+    service::{ServiceRequest, ServiceResponse},
+    HttpResponse,
+};
 
-/// `Middleware` for logging request and response info to the terminal.
+/// Middleware for logging request and response summaries to the terminal.
 ///
-/// `Logger` middleware uses standard log crate to log information. You should
-/// enable logger for `actix_web` package to see access log.
-/// ([`env_logger`](https://docs.rs/env_logger/*/env_logger/) or similar)
+/// This middleware uses the `log` crate to output information. Enable `log`'s output for the
+/// "actix_web" scope using [`env_logger`](https://docs.rs/env_logger) or similar crate.
 ///
-/// ## Usage
-///
-/// Create `Logger` middleware with the specified `format`.
-/// Default `Logger` could be created with `default` method, it uses the
-/// default format:
+/// # Default Format
+/// The [`default`](Logger::default) Logger uses the following format:
 ///
 /// ```plain
 /// %a "%r" %s %b "%{Referer}i" "%{User-Agent}i" %T
+///
+/// Example Output:
+/// 127.0.0.1:54278 "GET /test HTTP/1.1" 404 20 "-" "HTTPie/2.2.0" 0.001074
 /// ```
 ///
+/// # Usage
 /// ```rust
 /// use actix_web::{middleware::Logger, App};
 ///
-/// std::env::set_var("RUST_LOG", "actix_web=info");
-/// env_logger::init();
+/// // access logs are printed with the INFO level so ensure it is enabled by default
+/// env_logger::init_from_env(env_logger::Env::new().default_filter_or("info"));
 ///
 /// let app = App::new()
-///     .wrap(Logger::default())
+///     // .wrap(Logger::default())
 ///     .wrap(Logger::new("%a %{User-Agent}i"));
 /// ```
 ///
-/// ## Format
-///
-/// `%%`  The percent sign
-///
-/// `%a`  Remote IP-address (IP-address of proxy if using reverse proxy)
-///
-/// `%t`  Time when the request was started to process (in rfc3339 format)
-///
-/// `%r`  First line of request
-///
-/// `%s`  Response status code
-///
-/// `%b`  Size of response in bytes, including HTTP headers
-///
-/// `%T` Time taken to serve the request, in seconds with floating fraction in
-/// .06f format
-///
-/// `%D`  Time taken to serve the request, in milliseconds
-///
-/// `%U`  Request URL
-///
-/// `%{r}a`  Real IP remote address **\***
-///
-/// `%{FOO}i`  request.headers['FOO']
-///
-/// `%{FOO}o`  response.headers['FOO']
-///
-/// `%{FOO}e`  os.environ['FOO']
-///
-/// `%{FOO}xi`  [custom request replacement](Logger::custom_request_replace) labelled "FOO"
+/// # Format
+/// Variable | Description
+/// -------- | -----------
+/// `%%` | The percent sign
+/// `%a` | Peer IP address (or IP address of reverse proxy if used)
+/// `%t` | Time when the request started processing (in RFC 3339 format)
+/// `%r` | First line of request (Example: `GET /test HTTP/1.1`)
+/// `%s` | Response status code
+/// `%b` | Size of response in bytes, including HTTP headers
+/// `%T` | Time taken to serve the request, in seconds to 6 decimal places
+/// `%D` | Time taken to serve the request, in milliseconds
+/// `%U` | Request URL
+/// `%{r}a` | "Real IP" remote address **\***
+/// `%{FOO}i` |  `request.headers["FOO"]`
+/// `%{FOO}o` | `response.headers["FOO"]`
+/// `%{FOO}e` | `env_var["FOO"]`
+/// `%{FOO}xi` | [Custom request replacement](Logger::custom_request_replace) labelled "FOO"
 ///
 /// # Security
-///  **\*** It is calculated using
-///  [`ConnectionInfo::realip_remote_addr()`](crate::dev::ConnectionInfo::realip_remote_addr())
+/// **\*** "Real IP" remote address is calculated using
+/// [`ConnectionInfo::realip_remote_addr()`](crate::dev::ConnectionInfo::realip_remote_addr())
 ///
-///  If you use this value ensure that all requests come from trusted hosts, since it is trivial
-///  for the remote client to simulate being another client.
+/// If you use this value, ensure that all requests come from trusted hosts. Otherwise, it is
+/// trivial for the remote client to falsify their source IP address.
+#[derive(Debug)]
 pub struct Logger(Rc<Inner>);
 
+#[derive(Debug, Clone)]
 struct Inner {
     format: Format,
     exclude: HashSet<String>,
@@ -113,7 +107,7 @@ impl Logger {
         self
     }
 
-    /// Ignore and do not log access info for paths that match regex
+    /// Ignore and do not log access info for paths that match regex.
     pub fn exclude_regex<T: Into<String>>(mut self, path: T) -> Self {
         let inner = Rc::get_mut(&mut self.0).unwrap();
         let mut patterns = inner.exclude_regex.patterns().to_vec();
@@ -209,7 +203,7 @@ where
     }
 }
 
-/// Logger middleware
+/// Logger middleware service.
 pub struct LoggerMiddleware<S> {
     inner: Rc<Inner>,
     service: S,
@@ -224,9 +218,7 @@ where
     type Error = Error;
     type Future = LoggerResponse<S, B>;
 
-    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
-        self.service.poll_ready(cx)
-    }
+    actix_service::forward_ready!(service);
 
     fn call(&mut self, req: ServiceRequest) -> Self::Future {
         if self.inner.exclude.contains(req.path())
@@ -255,7 +247,6 @@ where
     }
 }
 
-#[doc(hidden)]
 #[pin_project::pin_project]
 pub struct LoggerResponse<S, B>
 where
@@ -325,7 +316,7 @@ pub struct StreamLog<B> {
 impl<B> PinnedDrop for StreamLog<B> {
     fn drop(self: Pin<&mut Self>) {
         if let Some(ref format) = self.format {
-            let render = |fmt: &mut Formatter<'_>| {
+            let render = |fmt: &mut fmt::Formatter<'_>| {
                 for unit in &format.0 {
                     unit.render(fmt, self.size, self.time)?;
                 }
@@ -356,9 +347,8 @@ impl<B: MessageBody> MessageBody for StreamLog<B> {
     }
 }
 
-/// A formatting style for the `Logger`, consisting of multiple
-/// `FormatText`s concatenated into one line.
-#[derive(Clone)]
+/// A formatting style for the `Logger` consisting of multiple concatenated `FormatText` items.
+#[derive(Debug, Clone)]
 struct Format(Vec<FormatText>);
 
 impl Default for Format {
@@ -430,13 +420,12 @@ impl Format {
     }
 }
 
-/// A string of text to be logged. This is either one of the data
-/// fields supported by the `Logger`, or a custom `String`.
-#[doc(hidden)]
+/// A string of text to be logged.
+///
+/// This is either one of the data fields supported by the `Logger`, or a custom `String`.
 #[non_exhaustive]
 #[derive(Debug, Clone)]
-// TODO: remove pub on next breaking change
-pub enum FormatText {
+enum FormatText {
     Str(String),
     Percent,
     RequestLine,
@@ -454,10 +443,8 @@ pub enum FormatText {
     CustomRequest(String, Option<CustomRequestFn>),
 }
 
-// TODO: remove pub on next breaking change
-#[doc(hidden)]
 #[derive(Clone)]
-pub struct CustomRequestFn {
+struct CustomRequestFn {
     inner_fn: Rc<dyn Fn(&ServiceRequest) -> String>,
 }
 
@@ -476,11 +463,11 @@ impl fmt::Debug for CustomRequestFn {
 impl FormatText {
     fn render(
         &self,
-        fmt: &mut Formatter<'_>,
+        fmt: &mut fmt::Formatter<'_>,
         size: usize,
         entry_time: OffsetDateTime,
     ) -> Result<(), fmt::Error> {
-        match *self {
+        match self {
             FormatText::Str(ref string) => fmt.write_str(string),
             FormatText::Percent => "%".fmt(fmt),
             FormatText::ResponseSize => size.fmt(fmt),
@@ -506,7 +493,7 @@ impl FormatText {
     }
 
     fn render_response<B>(&mut self, res: &HttpResponse<B>) {
-        match *self {
+        match self {
             FormatText::ResponseStatus => {
                 *self = FormatText::Str(format!("{}", res.status().as_u16()))
             }
@@ -527,7 +514,7 @@ impl FormatText {
     }
 
     fn render_request(&mut self, now: OffsetDateTime, req: &ServiceRequest) {
-        match &*self {
+        match self {
             FormatText::RequestLine => {
                 *self = if req.query_string().is_empty() {
                     FormatText::Str(format!(
@@ -594,11 +581,11 @@ impl FormatText {
 
 /// Converter to get a String from something that writes to a Formatter.
 pub(crate) struct FormatDisplay<'a>(
-    &'a dyn Fn(&mut Formatter<'_>) -> Result<(), fmt::Error>,
+    &'a dyn Fn(&mut fmt::Formatter<'_>) -> Result<(), fmt::Error>,
 );
 
 impl<'a> fmt::Display for FormatDisplay<'a> {
-    fn fmt(&self, fmt: &mut Formatter<'_>) -> Result<(), fmt::Error> {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
         (self.0)(fmt)
     }
 }
@@ -675,7 +662,7 @@ mod tests {
             unit.render_response(&resp);
         }
 
-        let render = |fmt: &mut Formatter<'_>| {
+        let render = |fmt: &mut fmt::Formatter<'_>| {
             for unit in &format.0 {
                 unit.render(fmt, 1024, now)?;
             }
@@ -708,7 +695,7 @@ mod tests {
         }
 
         let entry_time = OffsetDateTime::now_utc();
-        let render = |fmt: &mut Formatter<'_>| {
+        let render = |fmt: &mut fmt::Formatter<'_>| {
             for unit in &format.0 {
                 unit.render(fmt, 1024, entry_time)?;
             }
@@ -736,7 +723,7 @@ mod tests {
             unit.render_response(&resp);
         }
 
-        let render = |fmt: &mut Formatter<'_>| {
+        let render = |fmt: &mut fmt::Formatter<'_>| {
             for unit in &format.0 {
                 unit.render(fmt, 1024, now)?;
             }
@@ -769,7 +756,7 @@ mod tests {
         }
 
         let entry_time = OffsetDateTime::now_utc();
-        let render = |fmt: &mut Formatter<'_>| {
+        let render = |fmt: &mut fmt::Formatter<'_>| {
             for unit in &format.0 {
                 unit.render(fmt, 1024, entry_time)?;
             }
@@ -800,7 +787,7 @@ mod tests {
 
         unit.render_request(now, &req);
 
-        let render = |fmt: &mut Formatter<'_>| unit.render(fmt, 1024, now);
+        let render = |fmt: &mut fmt::Formatter<'_>| unit.render(fmt, 1024, now);
 
         let log_output = FormatDisplay(&render).to_string();
         assert_eq!(log_output, "custom_log");
diff --git a/src/middleware/mod.rs b/src/middleware/mod.rs
index af44fd8c7..e24782f07 100644
--- a/src/middleware/mod.rs
+++ b/src/middleware/mod.rs
@@ -1,19 +1,20 @@
-//! Middlewares
+//! Commonly used middleware.
+
+mod compat;
+mod condition;
+mod default_headers;
+mod err_handlers;
+mod logger;
+mod normalize;
+
+pub use self::compat::Compat;
+pub use self::condition::Condition;
+pub use self::default_headers::DefaultHeaders;
+pub use self::err_handlers::{ErrorHandlerResponse, ErrorHandlers};
+pub use self::logger::Logger;
+pub use self::normalize::{NormalizePath, TrailingSlash};
 
 #[cfg(feature = "compress")]
 mod compress;
 #[cfg(feature = "compress")]
 pub use self::compress::Compress;
-
-mod compat;
-mod condition;
-mod defaultheaders;
-pub mod errhandlers;
-mod logger;
-pub mod normalize;
-
-pub use self::compat::Compat;
-pub use self::condition::Condition;
-pub use self::defaultheaders::DefaultHeaders;
-pub use self::logger::Logger;
-pub use self::normalize::NormalizePath;
diff --git a/src/middleware/normalize.rs b/src/middleware/normalize.rs
index 4109364bf..89cab9073 100644
--- a/src/middleware/normalize.rs
+++ b/src/middleware/normalize.rs
@@ -1,60 +1,63 @@
 //! For middleware documentation, see [`NormalizePath`].
 
-use std::task::{Context, Poll};
-
 use actix_http::http::{PathAndQuery, Uri};
 use actix_service::{Service, Transform};
 use bytes::Bytes;
 use futures_util::future::{ready, Ready};
 use regex::Regex;
 
-use crate::service::{ServiceRequest, ServiceResponse};
-use crate::Error;
+use crate::{
+    service::{ServiceRequest, ServiceResponse},
+    Error,
+};
 
-/// To be used when constructing `NormalizePath` to define it's behavior.
+/// Determines the behavior of the [`NormalizePath`] middleware.
+///
+/// The default is `TrailingSlash::Trim`.
 #[non_exhaustive]
-#[derive(Clone, Copy)]
+#[derive(Debug, Clone, Copy)]
 pub enum TrailingSlash {
-    /// Always add a trailing slash to the end of the path.
-    /// This will require all routes to end in a trailing slash for them to be accessible.
-    Always,
+    /// Trim trailing slashes from the end of the path.
+    ///
+    /// Using this will require all routes to omit trailing slashes for them to be accessible.
+    Trim,
 
     /// Only merge any present multiple trailing slashes.
     ///
-    /// Note: This option provides the best compatibility with the v2 version of this middleware.
+    /// This option provides the best compatibility with behavior in actix-web v2.0.
     MergeOnly,
 
-    /// Trim trailing slashes from the end of the path.
-    Trim,
+    /// Always add a trailing slash to the end of the path.
+    ///
+    /// Using this will require all routes have a trailing slash for them to be accessible.
+    Always,
 }
 
 impl Default for TrailingSlash {
     fn default() -> Self {
-        TrailingSlash::Always
+        TrailingSlash::Trim
     }
 }
 
-#[derive(Default, Clone, Copy)]
-/// Middleware to normalize a request's path so that routes can be matched less strictly.
+/// Middleware for normalizing a request's path so that routes can be matched more flexibly.
 ///
 /// # Normalization Steps
-/// - Merges multiple consecutive slashes into one. (For example, `/path//one` always
-///   becomes `/path/one`.)
+/// - Merges consecutive slashes into one. (For example, `/path//one` always becomes `/path/one`.)
 /// - Appends a trailing slash if one is not present, removes one if present, or keeps trailing
 ///   slashes as-is, depending on which [`TrailingSlash`] variant is supplied
 ///   to [`new`](NormalizePath::new()).
 ///
 /// # Default Behavior
-/// The default constructor chooses to strip trailing slashes from the end
-/// ([`TrailingSlash::Trim`]), the effect is that route definitions should be defined without
-/// trailing slashes or else they will be inaccessible.
+/// The default constructor chooses to strip trailing slashes from the end of paths with them
+/// ([`TrailingSlash::Trim`]). The implication is that route definitions should be defined without
+/// trailing slashes or else they will be inaccessible (or vice versa when using the
+/// `TrailingSlash::Always` behavior), as shown in the example tests below.
 ///
-/// # Example
+/// # Usage
 /// ```rust
 /// use actix_web::{web, middleware, App};
 ///
-/// # #[actix_rt::test]
-/// # async fn normalize() {
+/// # actix_web::rt::System::new("doctest").block_on(async {
 /// let app = App::new()
 ///     .wrap(middleware::NormalizePath::default())
 ///     .route("/test", web::get().to(|| async { "test" }))
@@ -80,8 +83,9 @@ impl Default for TrailingSlash {
 /// let req = TestRequest::with_uri("/unmatchable/").to_request();
 /// let res = call_service(&mut app, req).await;
 /// assert_eq!(res.status(), StatusCode::NOT_FOUND);
-/// # }
+/// # })
 /// ```
+#[derive(Debug, Clone, Copy, Default)]
 pub struct NormalizePath(TrailingSlash);
 
 impl NormalizePath {
@@ -111,7 +115,6 @@ where
     }
 }
 
-#[doc(hidden)]
 pub struct NormalizePathNormalization<S> {
     service: S,
     merge_slash: Regex,
@@ -127,9 +130,7 @@ where
     type Error = Error;
     type Future = S::Future;
 
-    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
-        self.service.poll_ready(cx)
-    }
+    actix_service::forward_ready!(service);
 
     fn call(&mut self, mut req: ServiceRequest) -> Self::Future {
         let head = req.head_mut();
@@ -198,7 +199,7 @@ mod tests {
             App::new()
                 .wrap(NormalizePath::default())
                 .service(web::resource("/").to(HttpResponse::Ok))
-                .service(web::resource("/v1/something/").to(HttpResponse::Ok)),
+                .service(web::resource("/v1/something").to(HttpResponse::Ok)),
         )
         .await;
 
@@ -306,7 +307,7 @@ mod tests {
     #[actix_rt::test]
     async fn test_in_place_normalization() {
         let srv = |req: ServiceRequest| {
-            assert_eq!("/v1/something/", req.path());
+            assert_eq!("/v1/something", req.path());
             ready(Ok(req.into_response(HttpResponse::Ok().finish())))
         };
 
@@ -334,7 +335,7 @@ mod tests {
 
     #[actix_rt::test]
     async fn should_normalize_nothing() {
-        const URI: &str = "/v1/something/";
+        const URI: &str = "/v1/something";
 
         let srv = |req: ServiceRequest| {
             assert_eq!(URI, req.path());
@@ -353,10 +354,8 @@ mod tests {
 
     #[actix_rt::test]
     async fn should_normalize_no_trail() {
-        const URI: &str = "/v1/something";
-
         let srv = |req: ServiceRequest| {
-            assert_eq!(URI.to_string() + "/", req.path());
+            assert_eq!("/v1/something", req.path());
             ready(Ok(req.into_response(HttpResponse::Ok().finish())))
         };
 
@@ -365,7 +364,7 @@ mod tests {
             .await
             .unwrap();
 
-        let req = TestRequest::with_uri(URI).to_srv_request();
+        let req = TestRequest::with_uri("/v1/something/").to_srv_request();
         let res = normalize.call(req).await.unwrap();
         assert!(res.status().is_success());
     }
diff --git a/tests/test_server.rs b/tests/test_server.rs
index 2f8ce625e..43ee1230d 100644
--- a/tests/test_server.rs
+++ b/tests/test_server.rs
@@ -1,7 +1,9 @@
-use std::future::Future;
-use std::io::{Read, Write};
-use std::pin::Pin;
-use std::task::{Context, Poll};
+use std::{
+    future::Future,
+    io::{Read, Write},
+    pin::Pin,
+    task::{Context, Poll},
+};
 
 use actix_http::http::header::{
     ContentEncoding, ACCEPT_ENCODING, CONTENT_ENCODING, CONTENT_LENGTH,
@@ -9,15 +11,16 @@ use actix_http::http::header::{
 };
 use brotli2::write::{BrotliDecoder, BrotliEncoder};
 use bytes::Bytes;
-use flate2::read::GzDecoder;
-use flate2::write::{GzEncoder, ZlibDecoder, ZlibEncoder};
-use flate2::Compression;
+use flate2::{
+    read::GzDecoder,
+    write::{GzEncoder, ZlibDecoder, ZlibEncoder},
+    Compression,
+};
 use futures_util::ready;
 use rand::{distributions::Alphanumeric, Rng};
 
 use actix_web::dev::BodyEncoding;
-use actix_web::middleware::normalize::TrailingSlash;
-use actix_web::middleware::{Compress, NormalizePath};
+use actix_web::middleware::{Compress, NormalizePath, TrailingSlash};
 use actix_web::{dev, test, web, App, Error, HttpResponse};
 
 const STR: &str = "Hello World Hello World Hello World Hello World Hello World \