diff --git a/css-minifier-web/Cargo.toml b/css-minifier-web/Cargo.toml
index a9f86b6..796ac91 100644
--- a/css-minifier-web/Cargo.toml
+++ b/css-minifier-web/Cargo.toml
@@ -1,15 +1,14 @@
 [package]
 name = "css-minifier-web"
-version = "0.3.0"
+version = "0.5.0"
 authors = ["Mnwa <mihan@panfilov.biz>"]
 edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-css-minify = { version = "0.4", path = "../css-minify" }
+css-minify = { version = "0.5", path = "../css-minify" }
 actix-web = { version = "4" }
 actix-files = "0.6"
 yarte = "0.15"
-serde = { version = "1.0", features = ["derive"] }
-parking_lot = "0.12"
\ No newline at end of file
+serde = { version = "1.0", features = ["derive"] }
\ No newline at end of file
diff --git a/css-minifier-web/src/main.rs b/css-minifier-web/src/main.rs
index 4af862e..5947615 100644
--- a/css-minifier-web/src/main.rs
+++ b/css-minifier-web/src/main.rs
@@ -1,6 +1,5 @@
 use actix_web::{get, post, web, App, HttpResponse, HttpServer, Responder};
 use css_minify::optimizations::{Level, Minifier};
-use parking_lot::Mutex;
 use serde::Deserialize;
 use std::collections::hash_map::DefaultHasher;
 use std::hash::{Hash, Hasher};
@@ -22,13 +21,10 @@ async fn index() -> impl Responder {
 #[post("/")]
 async fn minify_css(
     request: web::Form<MinifyRequest>,
-    minifier: web::Data<Mutex<Minifier>>,
+    minifier: web::Data<Minifier>,
 ) -> impl Responder {
     let level = Level::from_str(&request.level).unwrap_or(Level::One);
-    let output_css = match minifier.lock().minify(&request.input_css, level) {
-        Ok(output_css) => output_css,
-        Err(e) => e.to_string(),
-    };
+    let output_css = minifier.minify(&request.input_css, level).unwrap_or_else(|e| e.to_string());
 
     match Template::call(&IndexTemplate {
         input_css: Some(request.into_inner().input_css),
@@ -55,10 +51,9 @@ async fn main_css(css: web::Data<MinifiedCss>) -> impl Responder {
 #[actix_web::main]
 async fn main() -> std::io::Result<()> {
     let mut hasher = DefaultHasher::default();
-    let minifier = web::Data::new(Mutex::new(Minifier::default()));
+    let minifier = web::Data::new(Minifier::default());
 
     let minified_css = minifier
-        .lock()
         .minify(include_str!("../static/main.css"), Level::Three)
         .expect("invalid css");
 
@@ -78,9 +73,9 @@ async fn main() -> std::io::Result<()> {
             .service(minify_css)
             .service(main_css)
     })
-    .bind(std::env::var("HTTP_HOST").unwrap_or_else(|_| "0.0.0.0:8081".into()))?
-    .run()
-    .await
+        .bind(std::env::var("HTTP_HOST").unwrap_or_else(|_| "0.0.0.0:8081".into()))?
+        .run()
+        .await
 }
 
 struct MinifiedCss {
diff --git a/css-minifier/Cargo.toml b/css-minifier/Cargo.toml
index 8e23a19..cc113ea 100644
--- a/css-minifier/Cargo.toml
+++ b/css-minifier/Cargo.toml
@@ -12,7 +12,7 @@ license = "Apache-2.0/MIT"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-css-minify = { version = "0.4", path = "../css-minify" }
+css-minify = { version = "0.5", path = "../css-minify" }
 clap = { version = "^4", features = ["derive"] }
 shellexpand = "3.1"
 indoc = "2.0"
diff --git a/css-minify/Cargo.toml b/css-minify/Cargo.toml
index fdedcf2..7780872 100644
--- a/css-minify/Cargo.toml
+++ b/css-minify/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "css-minify"
-version = "0.4.2"
+version = "0.5.0"
 authors = ["Mnwa <mihan@panfilov.biz>"]
 edition = "2021"
 description = "CSS parser and minificator based on nom"
diff --git a/css-minify/src/optimizations/font.rs b/css-minify/src/optimizations/font.rs
index 4387d7a..3ea98fd 100644
--- a/css-minify/src/optimizations/font.rs
+++ b/css-minify/src/optimizations/font.rs
@@ -5,7 +5,7 @@ use crate::structure::{Parameters, Value};
 pub(crate) struct FontTransformer;
 
 impl Transform for FontTransformer {
-    fn transform_parameters(&mut self, mut parameters: Parameters) -> Parameters {
+    fn transform_parameters(&self, mut parameters: Parameters) -> Parameters {
         parameters
             .iter_mut()
             .filter(|(name, _)| matches!(name.as_str(), "font-weight"))
@@ -34,25 +34,25 @@ mod test {
                     Some(Selector::Class("test".into())),
                     vec![],
                 )]
-                .into(),
+                    .into(),
                 parameters: {
                     let mut tmp = IndexMap::new();
                     tmp.insert("font-weight".into(), "bold".into());
                     tmp.into()
                 },
-            }),])),
+            }), ])),
             CssEntities(vec![CssEntity::Block(Block {
                 selectors: vec![SelectorWithPseudoClasses(
                     Some(Selector::Class("test".into())),
                     vec![],
                 )]
-                .into(),
+                    .into(),
                 parameters: {
                     let mut tmp = IndexMap::new();
                     tmp.insert("font-weight".into(), "700".into());
                     tmp.into()
                 },
-            }),])
+            }), ])
         )
     }
 }
diff --git a/css-minify/src/optimizations/merge_blocks.rs b/css-minify/src/optimizations/merge_blocks.rs
index a2c4358..ae62c41 100644
--- a/css-minify/src/optimizations/merge_blocks.rs
+++ b/css-minify/src/optimizations/merge_blocks.rs
@@ -6,15 +6,15 @@ use indexmap::map::IndexMap;
 pub struct MergeBlocks;
 
 impl Transform for MergeBlocks {
-    fn transform_parameters(&mut self, parameters: Parameters) -> Parameters {
+    fn transform_parameters(&self, parameters: Parameters) -> Parameters {
         parameters
     }
 
-    fn transform(&mut self, entity: CssEntity) -> CssEntity {
+    fn transform(&self, entity: CssEntity) -> CssEntity {
         entity
     }
 
-    fn transform_many(&mut self, entities: CssEntities) -> CssEntities {
+    fn transform_many(&self, entities: CssEntities) -> CssEntities {
         let mut blocks_to_merge = IndexMap::new();
         entities
             .0
@@ -43,15 +43,15 @@ impl Transform for MergeBlocks {
                         screen,
                         entities: self.transform_many(entities),
                     }
-                    .into(),
+                        .into(),
                     CssEntity::Supports(Supports {
-                        conditions,
-                        entities,
-                    }) => Supports {
+                                            conditions,
+                                            entities,
+                                        }) => Supports {
                         conditions,
                         entities: self.transform_many(entities),
                     }
-                    .into(),
+                        .into(),
                     entity => entity,
                 })
                 .collect(),
@@ -79,7 +79,7 @@ mod test {
                         Some(Selector::Class("test".into())),
                         vec![]
                     )]
-                    .into(),
+                        .into(),
                     parameters: {
                         let mut tmp = IndexMap::new();
                         tmp.insert("background-color".into(), "#f64e60 !important".into());
@@ -91,7 +91,7 @@ mod test {
                         Some(Selector::Class("test".into())),
                         vec![]
                     )]
-                    .into(),
+                        .into(),
                     parameters: {
                         let mut tmp = IndexMap::new();
                         tmp.insert("color".into(), "#f64e60 !important".into());
@@ -104,7 +104,7 @@ mod test {
                     Some(Selector::Class("test".into())),
                     vec![]
                 )]
-                .into(),
+                    .into(),
                 parameters: {
                     let mut tmp = IndexMap::new();
                     tmp.insert("background-color".into(), "#f64e60 !important".into());
diff --git a/css-minify/src/optimizations/merge_m_n_p.rs b/css-minify/src/optimizations/merge_m_n_p.rs
index fecde48..43f1840 100644
--- a/css-minify/src/optimizations/merge_m_n_p.rs
+++ b/css-minify/src/optimizations/merge_m_n_p.rs
@@ -13,7 +13,7 @@ pub struct Margin(Option<Value>, Option<Value>, Option<Value>, Option<Value>);
 pub struct Padding(Option<Value>, Option<Value>, Option<Value>, Option<Value>);
 
 impl Transform for Merge {
-    fn transform_parameters(&mut self, mut parameters: Parameters) -> Parameters {
+    fn transform_parameters(&self, mut parameters: Parameters) -> Parameters {
         let mut margin = Margin::default();
         let mut padding = Padding::default();
         parameters.0.iter().for_each(|(name, val)| {
@@ -235,7 +235,7 @@ mod test {
                         Parameters(map)
                     },
                 }
-                .into()
+                    .into()
             ),
             Block {
                 selectors: Selectors::default(),
@@ -245,7 +245,7 @@ mod test {
                     Parameters(map)
                 },
             }
-            .into()
+                .into()
         )
     }
 
@@ -264,7 +264,7 @@ mod test {
                         Parameters(map)
                     },
                 }
-                .into()
+                    .into()
             ),
             Block {
                 selectors: Selectors::default(),
@@ -274,7 +274,7 @@ mod test {
                     Parameters(map)
                 },
             }
-            .into()
+                .into()
         )
     }
 
@@ -293,7 +293,7 @@ mod test {
                         Parameters(map)
                     },
                 }
-                .into()
+                    .into()
             ),
             Block {
                 selectors: Selectors::default(),
@@ -303,7 +303,7 @@ mod test {
                     Parameters(map)
                 },
             }
-            .into()
+                .into()
         )
     }
 
@@ -322,7 +322,7 @@ mod test {
                         Parameters(map)
                     },
                 }
-                .into()
+                    .into()
             ),
             Block {
                 selectors: Selectors::default(),
@@ -332,7 +332,7 @@ mod test {
                     Parameters(map)
                 },
             }
-            .into()
+                .into()
         )
     }
 }
diff --git a/css-minify/src/optimizations/merge_media.rs b/css-minify/src/optimizations/merge_media.rs
index d911e87..7b5b4ec 100644
--- a/css-minify/src/optimizations/merge_media.rs
+++ b/css-minify/src/optimizations/merge_media.rs
@@ -6,11 +6,11 @@ use indexmap::map::IndexMap;
 pub struct MergeMedia;
 
 impl Transform for MergeMedia {
-    fn transform_parameters(&mut self, parameters: Parameters) -> Parameters {
+    fn transform_parameters(&self, parameters: Parameters) -> Parameters {
         parameters
     }
 
-    fn transform(&mut self, entity: CssEntity) -> CssEntity {
+    fn transform(&self, entity: CssEntity) -> CssEntity {
         match entity {
             CssEntity::Media(mut m) => {
                 m.screen = m.screen.replace(": ", ":");
@@ -20,7 +20,7 @@ impl Transform for MergeMedia {
         }
     }
 
-    fn transform_many(&mut self, entities: CssEntities) -> CssEntities {
+    fn transform_many(&self, entities: CssEntities) -> CssEntities {
         let mut media = IndexMap::new();
         entities
             .0
@@ -47,13 +47,13 @@ impl Transform for MergeMedia {
                 .filter(|e| !matches!(e, CssEntity::Media(_)))
                 .map(|e| match e {
                     CssEntity::Supports(Supports {
-                        conditions,
-                        entities,
-                    }) => Supports {
+                                            conditions,
+                                            entities,
+                                        }) => Supports {
                         conditions,
                         entities: self.transform_many(entities),
                     }
-                    .into(),
+                        .into(),
                     entity => entity,
                 })
                 .collect(),
@@ -88,10 +88,10 @@ mod test {
                             Some(Selector::Class("test".into())),
                             vec![]
                         )]
-                        .into(),
+                            .into(),
                         parameters: Default::default()
                     })]
-                    .into()
+                        .into()
                 }),
                 CssEntity::Media(Media {
                     screen: Value::from("only screen and (max-width: 992px)"),
@@ -100,10 +100,10 @@ mod test {
                             Some(Selector::Class("test2".into())),
                             vec![]
                         )]
-                        .into(),
+                            .into(),
                         parameters: Default::default()
                     })]
-                    .into()
+                        .into()
                 })
             ])),
             CssEntities(vec![CssEntity::Media(Media {
@@ -114,7 +114,7 @@ mod test {
                             Some(Selector::Class("test".into())),
                             vec![]
                         )]
-                        .into(),
+                            .into(),
                         parameters: Default::default()
                     }),
                     CssEntity::Block(Block {
@@ -122,11 +122,11 @@ mod test {
                             Some(Selector::Class("test2".into())),
                             vec![]
                         )]
-                        .into(),
+                            .into(),
                         parameters: Default::default()
                     })
                 ]
-                .into()
+                    .into()
             })])
         )
     }
diff --git a/css-minify/src/optimizations/merge_shorthand.rs b/css-minify/src/optimizations/merge_shorthand.rs
index 2cd24ec..a673bb5 100644
--- a/css-minify/src/optimizations/merge_shorthand.rs
+++ b/css-minify/src/optimizations/merge_shorthand.rs
@@ -8,7 +8,7 @@ use std::fmt::Display;
 pub struct MergeShortHand;
 
 impl Transform for MergeShortHand {
-    fn transform_parameters(&mut self, mut parameters: Parameters) -> Parameters {
+    fn transform_parameters(&self, mut parameters: Parameters) -> Parameters {
         let mut font = FontShortHand::default();
         let mut list = ListShortHand::default();
         let mut background = BackgroundShortHand::default();
@@ -508,7 +508,7 @@ mod test {
                         Parameters(map)
                     },
                 }
-                .into()
+                    .into()
             ),
             Block {
                 selectors: Selectors::default(),
@@ -521,7 +521,7 @@ mod test {
                     Parameters(map)
                 },
             }
-            .into()
+                .into()
         )
     }
 
@@ -540,7 +540,7 @@ mod test {
                         Parameters(map)
                     },
                 }
-                .into()
+                    .into()
             ),
             Block {
                 selectors: Selectors::default(),
@@ -553,7 +553,7 @@ mod test {
                     Parameters(map)
                 },
             }
-            .into()
+                .into()
         )
     }
 
@@ -569,7 +569,7 @@ mod test {
                         Parameters(map)
                     },
                 }
-                .into()
+                    .into()
             ),
             Block {
                 selectors: Selectors::default(),
@@ -579,7 +579,7 @@ mod test {
                     Parameters(map)
                 },
             }
-            .into()
+                .into()
         )
     }
 
@@ -597,7 +597,7 @@ mod test {
                         Parameters(map)
                     },
                 }
-                .into()
+                    .into()
             ),
             Block {
                 selectors: Selectors::default(),
@@ -607,7 +607,7 @@ mod test {
                     Parameters(map)
                 },
             }
-            .into()
+                .into()
         )
     }
 
@@ -625,7 +625,7 @@ mod test {
                         Parameters(map)
                     },
                 }
-                .into()
+                    .into()
             ),
             Block {
                 selectors: Selectors::default(),
@@ -635,7 +635,7 @@ mod test {
                     Parameters(map)
                 },
             }
-            .into()
+                .into()
         )
     }
 }
diff --git a/css-minify/src/optimizations/mod.rs b/css-minify/src/optimizations/mod.rs
index af4feb2..7bc7f14 100644
--- a/css-minify/src/optimizations/mod.rs
+++ b/css-minify/src/optimizations/mod.rs
@@ -35,7 +35,7 @@ pub struct Minifier {
 
 impl Minifier {
     /// Minify css input and return result with minified css string
-    pub fn minify<'a>(&mut self, input: &'a str, level: Level) -> MResult<'a> {
+    pub fn minify<'a>(&self, input: &'a str, level: Level) -> MResult<'a> {
         let mut result = parse_css(input)
             .map(|(_, blocks)| blocks)
             .map_err(|e| MError(input, e));
diff --git a/css-minify/src/optimizations/transformer.rs b/css-minify/src/optimizations/transformer.rs
index 15e2093..e0ad5ef 100644
--- a/css-minify/src/optimizations/transformer.rs
+++ b/css-minify/src/optimizations/transformer.rs
@@ -7,8 +7,8 @@ pub struct Transformer {
 }
 
 pub enum TransformerParameterFn {
-    Name(Box<dyn FnMut(Name) -> Name>),
-    Value(Box<dyn FnMut(Value) -> Value>),
+    Name(Box<dyn Fn(Name) -> Name + Send + Sync>),
+    Value(Box<dyn Fn(Value) -> Value + Send + Sync>),
 }
 
 unsafe impl Send for TransformerParameterFn {}
@@ -20,12 +20,12 @@ impl Transformer {
 }
 
 impl Transform for Transformer {
-    fn transform_parameters(&mut self, parameters: Parameters) -> Parameters {
+    fn transform_parameters(&self, parameters: Parameters) -> Parameters {
         parameters
             .0
             .into_iter()
             .map(|(mut name, mut value)| {
-                for transformer in self.parameters.iter_mut() {
+                for transformer in self.parameters.iter() {
                     match transformer {
                         TransformerParameterFn::Name(t) => name = t(name),
                         TransformerParameterFn::Value(t) => value = t(value),
@@ -39,8 +39,8 @@ impl Transform for Transformer {
 }
 
 pub trait Transform {
-    fn transform_parameters(&mut self, parameters: Parameters) -> Parameters;
-    fn transform(&mut self, entity: CssEntity) -> CssEntity {
+    fn transform_parameters(&self, parameters: Parameters) -> Parameters;
+    fn transform(&self, entity: CssEntity) -> CssEntity {
         match entity {
             CssEntity::Block(mut block) => {
                 block.parameters = self.transform_parameters(block.parameters);
@@ -56,9 +56,9 @@ pub trait Transform {
                     .into(),
             }),
             CssEntity::Supports(Supports {
-                conditions,
-                entities,
-            }) => CssEntity::Supports(Supports {
+                                    conditions,
+                                    entities,
+                                }) => CssEntity::Supports(Supports {
                 conditions,
                 entities: entities
                     .0
@@ -98,7 +98,7 @@ pub trait Transform {
             CssEntity::At(at) => CssEntity::At(at),
         }
     }
-    fn transform_many(&mut self, blocks: CssEntities) -> CssEntities {
+    fn transform_many(&self, blocks: CssEntities) -> CssEntities {
         CssEntities(blocks.0.into_iter().map(|b| self.transform(b)).collect())
     }
 }