diff --git a/package.json b/package.json
index a941d30f..46c252ce 100644
--- a/package.json
+++ b/package.json
@@ -7,10 +7,13 @@
         "url": "https://github.com/sponsors/fb55"
     },
     "repository": {
+        "type": "git",
         "url": "https://github.com/fb55/css-what"
     },
-    "main": "lib/index.js",
-    "types": "lib/index.d.ts",
+    "main": "lib/commonjs/index.js",
+    "module": "lib/es/index.js",
+    "types": "lib/es/index.d.ts",
+    "sideEffects": false,
     "files": [
         "lib/**/*"
     ],
@@ -24,7 +27,7 @@
         "format:es": "npm run lint:es -- --fix",
         "format:prettier": "npm run prettier -- --write",
         "prettier": "prettier '**/*.{ts,md,json,yml}'",
-        "build": "tsc",
+        "build": "tsc && tsc -p tsconfig.es.json",
         "prepare": "npm run build"
     },
     "devDependencies": {
@@ -45,7 +48,10 @@
     },
     "license": "BSD-2-Clause",
     "jest": {
-        "preset": "ts-jest"
+        "preset": "ts-jest",
+        "roots": [
+            "src"
+        ]
     },
     "prettier": {
         "tabWidth": 4
diff --git a/src/index.ts b/src/index.ts
index 03b8ecd3..1cf4a531 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,3 +1,3 @@
-export * from "./parse";
-export { default as parse } from "./parse";
-export { default as stringify } from "./stringify";
+export * from "./types";
+export { isTraversal, parse } from "./parse";
+export { stringify } from "./stringify";
diff --git a/src/parse.ts b/src/parse.ts
index 07c53404..f790a0c4 100644
--- a/src/parse.ts
+++ b/src/parse.ts
@@ -1,83 +1,12 @@
-export interface Options {
-    /**
-     * When false, tag names will not be lowercased.
-     * @default true
-     */
-    lowerCaseAttributeNames?: boolean;
-    /**
-     * When false, attribute names will not be lowercased.
-     * @default true
-     */
-    lowerCaseTags?: boolean;
-    /**
-     * When `true`, `xmlMode` implies both `lowerCaseTags` and `lowerCaseAttributeNames` are set to `false`.
-     * Also, `ignoreCase` on attributes will not be inferred based on HTML rules anymore.
-     * @default false
-     */
-    xmlMode?: boolean;
-}
-
-export type Selector =
-    | PseudoSelector
-    | PseudoElement
-    | AttributeSelector
-    | TagSelector
-    | UniversalSelector
-    | Traversal;
-
-export interface AttributeSelector {
-    type: "attribute";
-    name: string;
-    action: AttributeAction;
-    value: string;
-    ignoreCase: boolean | null;
-    namespace: string | null;
-}
-
-type DataType = Selector[][] | null | string;
-
-export interface PseudoSelector {
-    type: "pseudo";
-    name: string;
-    data: DataType;
-}
-
-export interface PseudoElement {
-    type: "pseudo-element";
-    name: string;
-}
-
-export interface TagSelector {
-    type: "tag";
-    name: string;
-    namespace: string | null;
-}
-
-export interface UniversalSelector {
-    type: "universal";
-    namespace: string | null;
-}
-
-export interface Traversal {
-    type: TraversalType;
-}
-
-export type AttributeAction =
-    | "any"
-    | "element"
-    | "end"
-    | "equals"
-    | "exists"
-    | "hyphen"
-    | "not"
-    | "start";
-
-export type TraversalType =
-    | "adjacent"
-    | "child"
-    | "descendant"
-    | "parent"
-    | "sibling";
+import type {
+    Options,
+    Selector,
+    AttributeSelector,
+    Traversal,
+    AttributeAction,
+    TraversalType,
+    DataType,
+} from "./types";
 
 const reName = /^[^\\#]?(?:\\(?:[\da-f]{1,6}\s?|.)|[\w\-\u00b0-\uFFFF])+/;
 const reEscape = /\\([\da-f]{1,6}\s?|(\s)|.)/gi;
@@ -220,10 +149,7 @@ function isWhitespace(c: string) {
  * The first dimension represents selectors separated by commas (eg. `sub1, sub2`),
  * the second contains the relevant tokens for that selector.
  */
-export default function parse(
-    selector: string,
-    options?: Options
-): Selector[][] {
+export function parse(selector: string, options?: Options): Selector[][] {
     const subselects: Selector[][] = [];
 
     const endIndex = parseSelector(subselects, `${selector}`, options, 0);
diff --git a/src/stringify.ts b/src/stringify.ts
index 1287932c..442b6db8 100644
--- a/src/stringify.ts
+++ b/src/stringify.ts
@@ -1,4 +1,4 @@
-import { Selector } from "./parse";
+import type { Selector } from "./types";
 
 const actionTypes: Record<string, string> = {
     equals: "",
@@ -29,7 +29,7 @@ const charsToEscape = new Set([
  *
  * @param selector Selector to stringify.
  */
-export default function stringify(selector: Selector[][]): string {
+export function stringify(selector: Selector[][]): string {
     return selector.map(stringifySubselector).join(", ");
 }
 
diff --git a/src/types.ts b/src/types.ts
new file mode 100644
index 00000000..c8d2d7c9
--- /dev/null
+++ b/src/types.ts
@@ -0,0 +1,80 @@
+export interface Options {
+    /**
+     * When false, tag names will not be lowercased.
+     * @default true
+     */
+    lowerCaseAttributeNames?: boolean;
+    /**
+     * When false, attribute names will not be lowercased.
+     * @default true
+     */
+    lowerCaseTags?: boolean;
+    /**
+     * When `true`, `xmlMode` implies both `lowerCaseTags` and `lowerCaseAttributeNames` are set to `false`.
+     * Also, `ignoreCase` on attributes will not be inferred based on HTML rules anymore.
+     * @default false
+     */
+    xmlMode?: boolean;
+}
+
+export type Selector =
+    | PseudoSelector
+    | PseudoElement
+    | AttributeSelector
+    | TagSelector
+    | UniversalSelector
+    | Traversal;
+
+export interface AttributeSelector {
+    type: "attribute";
+    name: string;
+    action: AttributeAction;
+    value: string;
+    ignoreCase: boolean | null;
+    namespace: string | null;
+}
+
+export type DataType = Selector[][] | null | string;
+
+export interface PseudoSelector {
+    type: "pseudo";
+    name: string;
+    data: DataType;
+}
+
+export interface PseudoElement {
+    type: "pseudo-element";
+    name: string;
+}
+
+export interface TagSelector {
+    type: "tag";
+    name: string;
+    namespace: string | null;
+}
+
+export interface UniversalSelector {
+    type: "universal";
+    namespace: string | null;
+}
+
+export interface Traversal {
+    type: TraversalType;
+}
+
+export type AttributeAction =
+    | "any"
+    | "element"
+    | "end"
+    | "equals"
+    | "exists"
+    | "hyphen"
+    | "not"
+    | "start";
+
+export type TraversalType =
+    | "adjacent"
+    | "child"
+    | "descendant"
+    | "parent"
+    | "sibling";
diff --git a/tsconfig.es.json b/tsconfig.es.json
new file mode 100644
index 00000000..8b7628c2
--- /dev/null
+++ b/tsconfig.es.json
@@ -0,0 +1,9 @@
+{
+    "extends": "./tsconfig.json",
+    "compilerOptions": {
+        "target": "ES2019",
+        "module": "es2015",
+        "outDir": "lib/es",
+        "moduleResolution": "node"
+    }
+}
diff --git a/tsconfig.json b/tsconfig.json
index 5d16dc75..6d6b80f3 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -7,7 +7,7 @@
         "declaration": true /* Generates corresponding '.d.ts' file. */,
         "declarationMap": true /* Generates a sourcemap for each corresponding '.d.ts' file. */,
         // "sourceMap": true,                     /* Generates corresponding '.map' file. */
-        "outDir": "lib" /* Redirect output structure to the directory. */,
+        "outDir": "lib/commonjs" /* Redirect output structure to the directory. */,
         // "importHelpers": true,                 /* Import emit helpers from 'tslib'. */
 
         /* Strict Type-Checking Options */