diff --git a/Cargo.toml b/Cargo.toml
index 1ec28cb..2648f15 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "bp3d-util"
-version = "1.4.2"
+version = "2.0.0"
 authors = ["Yuri Edward <yuri6037@outlook.com>"]
 edition = "2021"
 description = "OS independant Rust language utilities."
@@ -24,6 +24,7 @@ result = ["extension"]
 path = ["extension"]
 extension = []
 index-map = []
+string = []
 
 [package.metadata.docs.rs]
 all-features = true
diff --git a/src/extension.rs b/src/extension.rs
index b76ec3f..0eee3ff 100644
--- a/src/extension.rs
+++ b/src/extension.rs
@@ -1,4 +1,4 @@
-// Copyright (c) 2024, BlockProject 3D
+// Copyright (c) 2025, BlockProject 3D
 //
 // All rights reserved.
 //
@@ -32,19 +32,23 @@
 #[macro_export]
 macro_rules! extension {
     (
-        $(#[$meta: meta])*
-        pub extension $name: ident $(<$($generic: ident),*>)?: $ty: ident$(<$($generic1: ident),*>)? {
-            $($tokens: tt)*
-        }
+        $(
+            $(#[$meta: meta])*
+            pub extension $name: ident $(<$($generic: ident),*>)?: $ty: ty {
+                $($tokens: tt)*
+            }
+        )*
     ) => {
         mod sealing {
             pub trait Sealed {}
         }
-        impl$(<$($generic1),*>)? sealing::Sealed for $ty $(<$($generic1),*>)? {}
+        $(
+            impl$(<$($generic),*>)? sealing::Sealed for $ty {}
 
-        $(#[$meta])*
-        pub trait $name $(<$($generic),*>)? : sealing::Sealed {
-            $($tokens)*
-        }
+            $(#[$meta])*
+            pub trait $name $(<$($generic),*>)? : sealing::Sealed {
+                $($tokens)*
+            }
+        )*
     };
 }
diff --git a/src/lib.rs b/src/lib.rs
index 71b7a23..39112f1 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,4 +1,4 @@
-// Copyright (c) 2024, BlockProject 3D
+// Copyright (c) 2025, BlockProject 3D
 //
 // All rights reserved.
 //
@@ -54,3 +54,6 @@ pub mod extension;
 
 #[cfg(feature = "index-map")]
 pub mod index_map;
+
+#[cfg(feature = "string")]
+pub mod string;
diff --git a/src/result.rs b/src/result.rs
index 7ce3a02..fc00ac4 100644
--- a/src/result.rs
+++ b/src/result.rs
@@ -1,4 +1,4 @@
-// Copyright (c) 2024, BlockProject 3D
+// Copyright (c) 2025, BlockProject 3D
 //
 // All rights reserved.
 //
@@ -33,7 +33,7 @@ use std::error::Error;
 
 extension! {
     /// Result extensions designed to simplify console based tools.
-    pub extension ResultExt<T>: Result<T, E> {
+    pub extension ResultExt<T, E>: Result<T, E> {
         /// Expects a given result to unwrap without issues, in case the result is an error,
         /// this function exits the program.
         ///
@@ -47,7 +47,7 @@ extension! {
     }
 }
 
-impl<T, E: Error> ResultExt<T> for Result<T, E> {
+impl<T, E: Error> ResultExt<T, E> for Result<T, E> {
     fn expect_exit(self, msg: &str, code: i32) -> T {
         match self {
             Ok(v) => v,
diff --git a/src/string.rs b/src/string.rs
new file mode 100644
index 0000000..d7fef38
--- /dev/null
+++ b/src/string.rs
@@ -0,0 +1,266 @@
+// Copyright (c) 2025, BlockProject 3D
+//
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without modification,
+// are permitted provided that the following conditions are met:
+//
+//     * Redistributions of source code must retain the above copyright notice,
+//       this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above copyright notice,
+//       this list of conditions and the following disclaimer in the documentation
+//       and/or other materials provided with the distribution.
+//     * Neither the name of BlockProject 3D nor the names of its contributors
+//       may be used to endorse or promote products derived from this software
+//       without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+//! String utilities.
+
+use crate::extension;
+use std::borrow::Cow;
+
+/// The range trait that represents all supported range types for sub_nearest method.
+pub trait Range {
+    /// The actual implementation of nearest substring, see [sub_nearest](StrTools::sub_nearest) for
+    /// more information.
+    fn sub_nearest<'a>(&self, obj: &'a str) -> &'a str;
+}
+
+extension! {
+    /// The main StrTools extension trait.
+    pub extension StrTools: str {
+        /// A substring method which truncates strings at the nearest UTF-8 code rather than
+        /// panicking.
+        ///
+        /// # Panics
+        ///
+        /// This function still panics if the given range is out of bounds. It however does not panic
+        /// if the passed range falls withing a UTF-8 code.
+        fn sub_nearest(&self, range: impl Range) -> &str;
+
+        /// A string capitalize function which operates on UTF-8 strings.
+        fn capitalise(&self) -> Cow<str>;
+
+        /// A string decapitalize function which operates on UTF-8 strings. This essentially does
+        /// the inverse of the [capitalise](StrTools::capitalise) function.
+        fn decapitalise(&self) -> Cow<str>;
+    }
+
+    /// The main string tools operating on raw byte slices.
+    pub extension BufTools: [u8] {
+        /// A string capitalize function which operates on ASCII only strings.
+        fn capitalise_ascii(&self) -> Cow<[u8]>;
+
+        /// A string decapitalize function which operates on ASCII only strings. This essentially does
+        /// the inverse of the [capitalise](BufTools::capitalise_ascii) function.
+        fn decapitalise_ascii(&self) -> Cow<[u8]>;
+    }
+}
+
+fn utf8_max(buf: &[u8], max: usize) -> &[u8] {
+    if unsafe { buf.get_unchecked(max.unchecked_sub(1)) } & 0x80 == 0x00 {
+        &buf[..max]
+    } else {
+        let start = unsafe { max.unchecked_sub(1) };
+        let mut i = start;
+        unsafe {
+            while buf.get_unchecked(i) & 0xC0 == 0x80 {
+                i = i.unchecked_sub(1);
+            }
+            let n = start.unchecked_sub(i);
+            if (buf.get_unchecked(i) & 0xF0 == 0xF0 && n == 4)
+                || (buf.get_unchecked(i) & 0xE0 == 0xE0 && n == 3)
+                || (buf.get_unchecked(i) & 0xC0 == 0xC0 && n == 2)
+            {
+                &buf[..max]
+            } else {
+                &buf[..i]
+            }
+        }
+    }
+}
+
+fn utf8_min(buf: &[u8], start: usize) -> &[u8] {
+    if unsafe { buf.get_unchecked(start) } & 0x80 == 0x00 {
+        &buf[start..]
+    } else {
+        let start = start;
+        let mut i = start;
+        unsafe {
+            while i < buf.len() && buf.get_unchecked(i) & 0xC0 == 0x80 {
+                i = i.unchecked_add(1);
+            }
+            &buf[i..]
+        }
+    }
+}
+
+impl Range for std::ops::Range<usize> {
+    fn sub_nearest<'a>(&self, obj: &'a str) -> &'a str {
+        let bytes = obj.as_bytes();
+        let bytes = utf8_max(bytes, self.end);
+        if bytes.is_empty() {
+            return "";
+        }
+        let bytes = utf8_min(bytes, self.start);
+        unsafe { std::str::from_utf8(bytes).unwrap_unchecked() }
+    }
+}
+
+impl Range for std::ops::RangeTo<usize> {
+    fn sub_nearest<'a>(&self, obj: &'a str) -> &'a str {
+        let bytes = obj.as_bytes();
+        let bytes = utf8_max(bytes, self.end);
+        unsafe { std::str::from_utf8(bytes).unwrap_unchecked() }
+    }
+}
+
+impl Range for std::ops::RangeFrom<usize> {
+    fn sub_nearest<'a>(&self, obj: &'a str) -> &'a str {
+        let bytes = obj.as_bytes();
+        let bytes = utf8_min(bytes, self.start);
+        unsafe { std::str::from_utf8(bytes).unwrap_unchecked() }
+    }
+}
+
+impl StrTools for str {
+    fn sub_nearest(&self, range: impl Range) -> &str {
+        range.sub_nearest(self)
+    }
+
+    fn capitalise(&self) -> Cow<str> {
+        if self.is_empty() {
+            return self.into();
+        }
+        let first = unsafe { self.chars().next().unwrap_unchecked() };
+        if first.is_uppercase() {
+            self.into()
+        } else {
+            (self.sub_nearest(..1).to_uppercase() + self.sub_nearest(1..)).into()
+        }
+    }
+
+    fn decapitalise(&self) -> Cow<str> {
+        if self.is_empty() {
+            return self.into();
+        }
+        let first = unsafe { self.chars().next().unwrap_unchecked() };
+        if first.is_uppercase() {
+            (self.sub_nearest(..1).to_lowercase() + self.sub_nearest(1..)).into()
+        } else {
+            self.into()
+        }
+    }
+}
+
+impl BufTools for [u8] {
+    fn capitalise_ascii(&self) -> Cow<[u8]> {
+        if self.is_empty() {
+            return self.into();
+        }
+        if self[0] >= b'A' && self[0] <= b'Z' {
+            self.into()
+        } else {
+            let mut v: Vec<u8> = self.into();
+            v[0] = v[0].to_ascii_uppercase();
+            v.into()
+        }
+    }
+
+    fn decapitalise_ascii(&self) -> Cow<[u8]> {
+        if self.is_empty() {
+            return self.into();
+        }
+        if self[0] >= b'A' && self[0] <= b'Z' {
+            let mut v: Vec<u8> = self.into();
+            v[0] = v[0].to_ascii_lowercase();
+            v.into()
+        } else {
+            self.into()
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::string::{BufTools, StrTools};
+    use std::borrow::Cow;
+
+    #[test]
+    fn sub_basic() {
+        let str = "Hello";
+        assert_eq!(str.sub_nearest(..1), "H");
+        assert_eq!(str.sub_nearest(1..), "ello");
+    }
+
+    #[test]
+    fn truncate_ascii() {
+        let s = "this is a test";
+        assert_eq!(s.sub_nearest(..4), "this");
+        assert_eq!(&s[4..7], " is");
+        assert_eq!(s.sub_nearest(4..7), " is");
+    }
+
+    #[test]
+    fn truncate_utf8() {
+        let msg = "我";
+        assert_eq!(msg.sub_nearest(..3), "我");
+        assert_eq!(msg.sub_nearest(..1), "");
+        assert_eq!(msg.sub_nearest(1..), "");
+    }
+
+    #[test]
+    fn truncate_utf82() {
+        let msg = "我是";
+        assert_eq!(msg.sub_nearest(..6), "我是");
+        assert_eq!(msg.sub_nearest(..5), "我");
+        assert_eq!(msg.sub_nearest(1..), "是");
+    }
+
+    #[test]
+    fn truncate_utf83() {
+        let msg = "我abcd";
+        assert_eq!(msg.sub_nearest(..6), "我abc");
+        assert_eq!(msg.sub_nearest(1..), "abcd");
+        assert_eq!(msg.sub_nearest(1..2), "");
+        assert_eq!(msg.sub_nearest(1..4), "a");
+        assert_eq!(msg.sub_nearest(1..5), "ab");
+        assert_eq!(msg.sub_nearest(1..msg.len()), "abcd");
+        assert_eq!(msg.sub_nearest(1..msg.len() - 1), "abc");
+    }
+
+    #[test]
+    fn basic_capitalize() {
+        let msg = "abc";
+        let msg1 = "Abc";
+        assert_eq!(msg.capitalise(), "Abc");
+        assert_eq!(msg1.capitalise(), "Abc");
+        assert!(matches!(msg1.capitalise(), Cow::Borrowed(_)));
+        assert_eq!(msg1.decapitalise(), "abc");
+    }
+
+    #[test]
+    fn ascii_capitalize() {
+        let msg = "abc";
+        let msg1 = "Abc";
+        assert_eq!(&*msg.as_bytes().capitalise_ascii(), b"Abc");
+        assert_eq!(&*msg1.as_bytes().capitalise_ascii(), b"Abc");
+        assert!(matches!(
+            msg1.as_bytes().capitalise_ascii(),
+            Cow::Borrowed(_)
+        ));
+        assert_eq!(&*msg1.as_bytes().decapitalise_ascii(), b"abc");
+    }
+}