diff --git a/src/array/arrayContains/algo.ts b/src/array/arrayContains/algo.ts
new file mode 100644
index 0000000..ef37fdf
--- /dev/null
+++ b/src/array/arrayContains/algo.ts
@@ -0,0 +1,13 @@
+export type _ArrayContains<
+  Array extends (string | number | boolean)[],
+  Value extends string | number | boolean,
+  IndexArr extends number[] = [],
+> = IndexArr["length"] extends Array["length"]
+  ? false
+  : Array[IndexArr["length"]] extends Value
+    ? true
+    : _ArrayContains<
+        Array,
+        Value,
+        [...IndexArr, 7]
+      >
diff --git a/src/array/arrayContains/index.test.ts b/src/array/arrayContains/index.test.ts
new file mode 100644
index 0000000..a10f9dc
--- /dev/null
+++ b/src/array/arrayContains/index.test.ts
@@ -0,0 +1,104 @@
+import {
+  describe,
+  it,
+  expectTypeOf,
+} from "vitest"
+import type { _ArrayContains } from "./algo"
+
+describe("ArrayContains type tests", () => {
+  it("should return true if the array contains the element", () => {
+    type T1 = _ArrayContains<[1, 2, 3], 2> // 2 is in the array
+    type T2 = _ArrayContains<["a", "b", "c"], "b"> // "b" is in the array
+    type T3 = _ArrayContains<
+      [true, false, true],
+      true
+    > // true is in the array
+    expectTypeOf<T1>().toEqualTypeOf<true>()
+    expectTypeOf<T2>().toEqualTypeOf<true>()
+    expectTypeOf<T3>().toEqualTypeOf<true>()
+  })
+
+  it("should return false if the array does not contain the element", () => {
+    type T1 = _ArrayContains<[1, 2, 3], 4> // 4 is not in the array
+    type T2 = _ArrayContains<["a", "b", "c"], "d"> // "d" is not in the array
+    type T3 = _ArrayContains<
+      [true, false, true],
+      false
+    > // false is in the array
+    type T4 = _ArrayContains<[], "anything"> // empty array, always false
+    expectTypeOf<T1>().toEqualTypeOf<false>()
+    expectTypeOf<T2>().toEqualTypeOf<false>()
+    expectTypeOf<T3>().toEqualTypeOf<true>()
+    expectTypeOf<T4>().toEqualTypeOf<false>()
+  })
+
+  it("should handle arrays of mixed types correctly", () => {
+    type T1 = _ArrayContains<[1, "a", true], 1> // 1 is in the array
+    type T2 = _ArrayContains<[1, "a", true], "a"> // "a" is in the array
+    type T3 = _ArrayContains<
+      [1, "a", true],
+      false
+    > // false is not in the array
+    type T4 = _ArrayContains<[1, "a", true], "b"> // "b" is not in the array
+    expectTypeOf<T1>().toEqualTypeOf<true>()
+    expectTypeOf<T2>().toEqualTypeOf<true>()
+    expectTypeOf<T3>().toEqualTypeOf<false>()
+    expectTypeOf<T4>().toEqualTypeOf<false>()
+  })
+
+  it("should return false for incompatible types", () => {
+    type T1 = _ArrayContains<[1, 2, 3], "1"> // string "1" is not the same as number 1
+    type T2 = _ArrayContains<["a", "b", "c"], 1> // numbers are not in a string array
+    type T3 = _ArrayContains<
+      [true, false],
+      "true"
+    > // string "true" is not the same as boolean true
+    expectTypeOf<T1>().toEqualTypeOf<false>()
+    expectTypeOf<T2>().toEqualTypeOf<false>()
+    expectTypeOf<T3>().toEqualTypeOf<false>()
+  })
+
+  it("should handle arrays of a single type", () => {
+    type T1 = _ArrayContains<
+      ["apple", "banana", "cherry"],
+      "banana"
+    > // "banana" is in the array
+    type T2 = _ArrayContains<[1, 2, 3], 3> // 3 is in the array
+    type T3 = _ArrayContains<[true, false], true> // true is in the array
+    type T4 = _ArrayContains<[true, false], false> // false is in the array
+    expectTypeOf<T1>().toEqualTypeOf<true>()
+    expectTypeOf<T2>().toEqualTypeOf<true>()
+    expectTypeOf<T3>().toEqualTypeOf<true>()
+    expectTypeOf<T4>().toEqualTypeOf<true>()
+  })
+
+  it("should handle arrays with duplicate values", () => {
+    type T1 = _ArrayContains<[1, 2, 2, 3], 2> // 2 appears multiple times, still true
+    type T2 = _ArrayContains<
+      ["a", "b", "a", "c"],
+      "a"
+    > // "a" appears multiple times, still true
+    type T3 = _ArrayContains<
+      [true, false, true],
+      false
+    > // false is present, still true
+    expectTypeOf<T1>().toEqualTypeOf<true>()
+    expectTypeOf<T2>().toEqualTypeOf<true>()
+    expectTypeOf<T3>().toEqualTypeOf<true>()
+  })
+
+  it("should return false for arrays that do not match the specified type", () => {
+    type T1 = _ArrayContains<
+      ["a", "b", "c"],
+      number
+    > // numbers are not in a string array
+    type T2 = _ArrayContains<[1, 2, 3], boolean> // booleans are not in a number array
+    type T3 = _ArrayContains<
+      [true, false],
+      string
+    > // strings are not in a boolean array
+    expectTypeOf<T1>().toEqualTypeOf<false>()
+    expectTypeOf<T2>().toEqualTypeOf<false>()
+    expectTypeOf<T3>().toEqualTypeOf<false>()
+  })
+})
diff --git a/src/array/arrayContains/index.ts b/src/array/arrayContains/index.ts
new file mode 100644
index 0000000..0adbe05
--- /dev/null
+++ b/src/array/arrayContains/index.ts
@@ -0,0 +1,20 @@
+/**
+ * A type that searches for a match in the array, if there is a match between array element and given the thing you look for it returns true.
+ * Only primitive values are supported.
+ *
+ * @template Array - Array of primitive values.
+ * @template Value - Value you look for.
+ * @returns {boolean} - Returns `true` if array contains or 'false' otherwise.
+ *
+ *
+ * @example
+ * type ArrayContainsBanana = ArrayContains<["apple", "banana", "cherry"], "banana">; // Result: true
+ * type ArrayContainsFalse = StartsWith<[true, true, false], false>; // Result: true
+ */
+
+import type { _ArrayContains } from "./algo"
+
+export type ArrayContains<
+  A extends (string | number | boolean)[],
+  V extends string | number | boolean,
+> = _ArrayContains<A, V, []>
diff --git a/src/string/strToArr/algo.ts b/src/string/strToArr/algo.ts
index 8fca604..6f748a3 100644
--- a/src/string/strToArr/algo.ts
+++ b/src/string/strToArr/algo.ts
@@ -1,9 +1,9 @@
-export type _StrToArr<Str extends string, Acc extends string[]> = [
-  Str,
-] extends [`${infer First}${infer Rest}`]
+export type _StrToArr<
+  Str extends string,
+  Acc extends string[],
+> = [Str] extends [`${infer First}${infer Rest}`]
   ? _StrToArr<Rest, [...Acc, First]>
   : Acc
 
-export type _StrToArr_Back$<Str> = Str extends string
-  ? _StrToArr<Str, []>
-  : never
+export type _StrToArr_Back$<Str> =
+  Str extends string ? _StrToArr<Str, []> : never
diff --git a/src/string/toKebabCase/algo.ts b/src/string/toKebabCase/algo.ts
new file mode 100644
index 0000000..f7d3e2c
--- /dev/null
+++ b/src/string/toKebabCase/algo.ts
@@ -0,0 +1,25 @@
+import type { ArrayContains } from "array/arrayContains"
+import type { _StrToArr } from "string/strToArr/algo"
+
+type Separators = [" ", "_", "-"]
+
+type Saintize<Result extends string> =
+  Result extends `-${infer Rest}`
+    ? Saintize<Rest>
+    : Result extends `${infer P}--${infer Q}`
+      ? Saintize<`${P}-${Q}`>
+      : Uncapitalize<Result>
+
+export type _ToKebabCase<
+  Str extends string,
+  Builder extends string = "",
+> = Str extends `${infer First}${infer Rest}`
+  ? ArrayContains<Separators, First> extends true
+    ? _ToKebabCase<Rest, `${Builder}-`>
+    : First extends Uppercase<First>
+      ? _ToKebabCase<
+          Rest,
+          `${Builder}-${Lowercase<First>}`
+        >
+      : _ToKebabCase<Rest, `${Builder}${First}`>
+  : Saintize<Builder>
diff --git a/src/string/toKebabCase/index.test.ts b/src/string/toKebabCase/index.test.ts
new file mode 100644
index 0000000..ee69f89
--- /dev/null
+++ b/src/string/toKebabCase/index.test.ts
@@ -0,0 +1,91 @@
+import {
+  describe,
+  it,
+  expectTypeOf,
+} from "vitest"
+import type { _ToKebabCase } from "./algo"
+
+describe("_ToKebabCase type tests", () => {
+  it("should convert camelCase to kebab-case", () => {
+    type T1 = _ToKebabCase<"camelCase">
+    type T2 = _ToKebabCase<"thisIsATest">
+    type T3 = _ToKebabCase<"anotherExampleHere">
+    expectTypeOf<T1>().toEqualTypeOf<"camel-case">()
+    expectTypeOf<T2>().toEqualTypeOf<"this-is-a-test">()
+    expectTypeOf<T3>().toEqualTypeOf<"another-example-here">()
+  })
+
+  it("should handle strings with separators (space, underscore, hyphen)", () => {
+    type T1 = _ToKebabCase<"hello world">
+    type T2 = _ToKebabCase<"hello_world">
+    type T3 = _ToKebabCase<"hello-world">
+    expectTypeOf<T1>().toEqualTypeOf<"hello-world">()
+    expectTypeOf<T2>().toEqualTypeOf<"hello-world">()
+    expectTypeOf<T3>().toEqualTypeOf<"hello-world">()
+  })
+
+  it("should handle uppercase letters properly", () => {
+    type T1 = _ToKebabCase<"HelloWorld">
+    type T2 = _ToKebabCase<"UpperCase">
+    expectTypeOf<T1>().toEqualTypeOf<"hello-world">()
+    expectTypeOf<T2>().toEqualTypeOf<"upper-case">()
+  })
+
+  it("should handle strings with mixed separators and cases", () => {
+    type T1 =
+      _ToKebabCase<"MixOf_Separators And-Cases">
+    type T2 =
+      _ToKebabCase<"another_Example-Here Today">
+    expectTypeOf<T1>().toEqualTypeOf<"mix-of-separators-and-cases">()
+    expectTypeOf<T2>().toEqualTypeOf<"another-example-here-today">()
+  })
+
+  it("should handle strings without any uppercase letters or separators", () => {
+    type T1 = _ToKebabCase<"lowercase">
+    type T2 = _ToKebabCase<"already-kebab">
+    type T3 = _ToKebabCase<"plain">
+    expectTypeOf<T1>().toEqualTypeOf<"lowercase">()
+    expectTypeOf<T2>().toEqualTypeOf<"already-kebab">()
+    expectTypeOf<T3>().toEqualTypeOf<"plain">()
+  })
+
+  it("should handle empty strings and strings without transformations", () => {
+    type T1 = _ToKebabCase<"">
+    type T2 = _ToKebabCase<"simple">
+    expectTypeOf<T1>().toEqualTypeOf<"">()
+    expectTypeOf<T2>().toEqualTypeOf<"simple">()
+  })
+
+  it("should handle strings with leading or trailing separators", () => {
+    type T1 = _ToKebabCase<"trailing-space ">
+    type T2 = _ToKebabCase<"trailing-hyphen-">
+    expectTypeOf<T1>().toEqualTypeOf<"trailing-space-">()
+    expectTypeOf<T2>().toEqualTypeOf<"trailing-hyphen-">()
+  })
+
+  it("should handle uppercase strings", () => {
+    type T1 = _ToKebabCase<"UPPERCASE">
+    type T2 = _ToKebabCase<"MIXEDUppercase">
+    expectTypeOf<T1>().toEqualTypeOf<"u-p-p-e-r-c-a-s-e">()
+    expectTypeOf<T2>().toEqualTypeOf<"m-i-x-e-d-uppercase">()
+  })
+
+  it("should handle strings with multiple separators in sequence", () => {
+    type T1 =
+      _ToKebabCase<"string__with__multiple__underscores">
+    type T2 =
+      _ToKebabCase<"string--with--multiple--hyphens">
+    type T3 =
+      _ToKebabCase<"string  with  multiple  spaces">
+    expectTypeOf<T1>().toEqualTypeOf<"string-with-multiple-underscores">()
+    expectTypeOf<T2>().toEqualTypeOf<"string-with-multiple-hyphens">()
+    expectTypeOf<T3>().toEqualTypeOf<"string-with-multiple-spaces">()
+  })
+
+  it("should preserve existing kebab-case", () => {
+    type T1 = _ToKebabCase<"already-kebab-case">
+    type T2 = _ToKebabCase<"more-kebab-case-here">
+    expectTypeOf<T1>().toEqualTypeOf<"already-kebab-case">()
+    expectTypeOf<T2>().toEqualTypeOf<"more-kebab-case-here">()
+  })
+})
diff --git a/src/string/toKebabCase/index.ts b/src/string/toKebabCase/index.ts
new file mode 100644
index 0000000..60c4496
--- /dev/null
+++ b/src/string/toKebabCase/index.ts
@@ -0,0 +1,15 @@
+/**
+ * A ToKebabCase implementation on a type level.
+ *
+ * @template String - A string to turn into kebab case.
+ * @returns {string} - a-string-to-turn-into-kebab-case.
+ *
+ *
+ * @example
+ * type KebabCased = ToKebabCase<"MixOf_Separators And-Cases">; // Result: mix-of-separators-and-cases
+ */
+
+import type { _ToKebabCase } from "./algo"
+
+export type ToKebabCase<Str extends string> =
+  _ToKebabCase<Str>
diff --git a/src/string/toSnakeCase/algo.ts b/src/string/toSnakeCase/algo.ts
new file mode 100644
index 0000000..af297f0
--- /dev/null
+++ b/src/string/toSnakeCase/algo.ts
@@ -0,0 +1,25 @@
+import type { ArrayContains } from "array/arrayContains"
+import type { _StrToArr } from "string/strToArr/algo"
+
+type Separators = [" ", "_", "-"]
+
+type Saintize<Result extends string> =
+  Result extends `_${infer Rest}`
+    ? Saintize<Rest>
+    : Result extends `${infer P}__${infer Q}`
+      ? Saintize<`${P}_${Q}`>
+      : Uncapitalize<Result>
+
+export type _ToSnakeCase<
+  Str extends string,
+  Builder extends string = "",
+> = Str extends `${infer First}${infer Rest}`
+  ? ArrayContains<Separators, First> extends true
+    ? _ToSnakeCase<Rest, `${Builder}_`>
+    : First extends Uppercase<First>
+      ? _ToSnakeCase<
+          Rest,
+          `${Builder}_${Lowercase<First>}`
+        >
+      : _ToSnakeCase<Rest, `${Builder}${First}`>
+  : Saintize<Builder>
diff --git a/src/string/toSnakeCase/index.test.ts b/src/string/toSnakeCase/index.test.ts
new file mode 100644
index 0000000..ff78c05
--- /dev/null
+++ b/src/string/toSnakeCase/index.test.ts
@@ -0,0 +1,91 @@
+import {
+  describe,
+  it,
+  expectTypeOf,
+} from "vitest"
+import type { _ToSnakeCase } from "./algo"
+
+describe("_ToSnakeCase type tests", () => {
+  it("should convert camelCase to snake_case", () => {
+    type T1 = _ToSnakeCase<"camelCase">
+    type T2 = _ToSnakeCase<"thisIsATest">
+    type T3 = _ToSnakeCase<"anotherExampleHere">
+    expectTypeOf<T1>().toEqualTypeOf<"camel_case">()
+    expectTypeOf<T2>().toEqualTypeOf<"this_is_a_test">()
+    expectTypeOf<T3>().toEqualTypeOf<"another_example_here">()
+  })
+
+  it("should handle strings with separators (space, underscore, hyphen)", () => {
+    type T1 = _ToSnakeCase<"hello world">
+    type T2 = _ToSnakeCase<"hello_world">
+    type T3 = _ToSnakeCase<"hello-world">
+    expectTypeOf<T1>().toEqualTypeOf<"hello_world">()
+    expectTypeOf<T2>().toEqualTypeOf<"hello_world">()
+    expectTypeOf<T3>().toEqualTypeOf<"hello_world">()
+  })
+
+  it("should handle uppercase letters properly", () => {
+    type T1 = _ToSnakeCase<"HelloWorld">
+    type T2 = _ToSnakeCase<"UpperCase">
+    expectTypeOf<T1>().toEqualTypeOf<"hello_world">()
+    expectTypeOf<T2>().toEqualTypeOf<"upper_case">()
+  })
+
+  it("should handle strings with mixed separators and cases", () => {
+    type T1 =
+      _ToSnakeCase<"MixOf_Separators And-Cases">
+    type T2 =
+      _ToSnakeCase<"another_Example-Here Today">
+    expectTypeOf<T1>().toEqualTypeOf<"mix_of_separators_and_cases">()
+    expectTypeOf<T2>().toEqualTypeOf<"another_example_here_today">()
+  })
+
+  it("should handle strings without any uppercase letters or separators", () => {
+    type T1 = _ToSnakeCase<"lowercase">
+    type T2 = _ToSnakeCase<"already_snake">
+    type T3 = _ToSnakeCase<"plain">
+    expectTypeOf<T1>().toEqualTypeOf<"lowercase">()
+    expectTypeOf<T2>().toEqualTypeOf<"already_snake">()
+    expectTypeOf<T3>().toEqualTypeOf<"plain">()
+  })
+
+  it("should handle empty strings and strings without transformations", () => {
+    type T1 = _ToSnakeCase<"">
+    type T2 = _ToSnakeCase<"simple">
+    expectTypeOf<T1>().toEqualTypeOf<"">()
+    expectTypeOf<T2>().toEqualTypeOf<"simple">()
+  })
+
+  it("should handle strings with leading or trailing separators", () => {
+    type T1 = _ToSnakeCase<"trailing space ">
+    type T2 = _ToSnakeCase<"trailing-hyphen-">
+    expectTypeOf<T1>().toEqualTypeOf<"trailing_space_">()
+    expectTypeOf<T2>().toEqualTypeOf<"trailing_hyphen_">()
+  })
+
+  it("should handle uppercase strings", () => {
+    type T1 = _ToSnakeCase<"UPPERCASE">
+    type T2 = _ToSnakeCase<"MIXEDUppercase">
+    expectTypeOf<T1>().toEqualTypeOf<"u_p_p_e_r_c_a_s_e">()
+    expectTypeOf<T2>().toEqualTypeOf<"m_i_x_e_d_uppercase">()
+  })
+
+  it("should handle strings with multiple separators in sequence", () => {
+    type T1 =
+      _ToSnakeCase<"string__with__multiple__underscores">
+    type T2 =
+      _ToSnakeCase<"string--with--multiple--hyphens">
+    type T3 =
+      _ToSnakeCase<"string  with  multiple  spaces">
+    expectTypeOf<T1>().toEqualTypeOf<"string_with_multiple_underscores">()
+    expectTypeOf<T2>().toEqualTypeOf<"string_with_multiple_hyphens">()
+    expectTypeOf<T3>().toEqualTypeOf<"string_with_multiple_spaces">()
+  })
+
+  it("should preserve existing snake_case", () => {
+    type T1 = _ToSnakeCase<"already_snake_case">
+    type T2 = _ToSnakeCase<"more_snake_case_here">
+    expectTypeOf<T1>().toEqualTypeOf<"already_snake_case">()
+    expectTypeOf<T2>().toEqualTypeOf<"more_snake_case_here">()
+  })
+})
diff --git a/src/string/toSnakeCase/index.ts b/src/string/toSnakeCase/index.ts
new file mode 100644
index 0000000..268ba4a
--- /dev/null
+++ b/src/string/toSnakeCase/index.ts
@@ -0,0 +1,15 @@
+/**
+ * A ToSnakeCase implementation on a type level.
+ *
+ * @template String - A string to turn into snake case.
+ * @returns {string} - a_string_to_turn_into_snake_case.
+ *
+ *
+ * @example
+ * type SnakeCased = ToSnakeCase<"MixOf_Separators And-Cases">; // Result: mix_of_separators_and_cases
+ */
+
+import type { _ToSnakeCase } from "./algo"
+
+export type ToSnakeCase<Str extends string> =
+  _ToSnakeCase<Str>