diff --git a/README.md b/README.md
index 3bcc11e..b3c9061 100644
--- a/README.md
+++ b/README.md
@@ -20,9 +20,19 @@ yarn add @getalby/lightning-tools
 
 or for use without any build tools:
 
-```
-// lightning-tools now available at window.lightningTools
-<script src="https://cdn.jsdelivr.net/npm/@getalby/lightning-tools@latest/dist/index.browser.js"></script>
+```html
+<script type="module">
+  import { LightningAddress } from "https://esm.sh/@getalby/lightning-tools@5.0.0"; // jsdelivr.net, skypack.dev also work
+
+  // use LightningAddress normally...
+  (async () => {
+    const ln = new LightningAddress("hello@getalby.com");
+    // fetch the LNURL data
+    await ln.fetch();
+    // get the LNURL-pay data:
+    console.log(ln.lnurlpData);
+  })();
+</script>
 ```
 
 **This library relies on a global `fetch()` function which will work in [browsers](https://caniuse.com/?search=fetch) and node v18 or newer.** (In older versions you have to use a polyfill.)
@@ -179,7 +189,7 @@ import { fetchWithL402 } from "@getalby/lightning-tools";
 await fetchWithL402(
   "https://lsat-weather-api.getalby.repl.co/kigali",
   {},
-  { store: window.localStorage },
+  { store: window.localStorage }
 )
   .then((res) => res.json())
   .then(console.log);
@@ -198,7 +208,7 @@ const nwc = new webln.NostrWebLNProvider({
 await fetchWithL402(
   "https://lsat-weather-api.getalby.repl.co/kigali",
   {},
-  { webln: nwc },
+  { webln: nwc }
 )
   .then((res) => res.json())
   .then(console.log);
@@ -211,7 +221,7 @@ import { l402 } from "@getalby/lightning-tools";
 await l402.fetchWithL402(
   "https://lsat-weather-api.getalby.repl.co/kigali",
   {},
-  { store: new l402.storage.NoStorage() },
+  { store: new l402.storage.NoStorage() }
 );
 ```
 
@@ -262,13 +272,25 @@ This library uses a [proxy](https://github.com/getAlby/lightning-address-details
 
 You can disable the proxy by explicitly setting the proxy to false when initializing a lightning address:
 
+```js
+const lightningAddress = new LightningAddress("hello@getalby.com", {
+  proxy: false,
+});
 ```
-const lightningAddress = new LightningAddress("hello@getalby.com", {proxy: false});
+
+## crypto dependency
+
+If you get an `crypto is not defined` in NodeJS error you have to import it first:
+
+```js
+import * as crypto from 'crypto'; // or 'node:crypto'
+globalThis.crypto = crypto as any;
+//or: global.crypto = require('crypto');
 ```
 
 ## fetch() dependency
 
-This library relies on a global fetch object which will work in browsers and node v18.x or newer. In old version yoi can manually install a global fetch option or polyfill if needed.
+This library relies on a global fetch object which will work in browsers and node v18.x or newer. In old version you can manually install a global fetch option or polyfill if needed.
 
 For example:
 
diff --git a/examples/request-invoice.js b/examples/request-invoice.js
new file mode 100644
index 0000000..7d2f60f
--- /dev/null
+++ b/examples/request-invoice.js
@@ -0,0 +1,13 @@
+import * as crypto from "crypto"; // or 'node:crypto'
+global.crypto = crypto;
+import { LightningAddress } from "@getalby/lightning-tools";
+
+const ln = new LightningAddress("hello@getalby.com");
+
+await ln.fetch();
+// request an invoice for 1000 satoshis
+// this returns a new `Invoice` class that can also be used to validate the payment
+const invoice = await ln.requestInvoice({ satoshi: 1000 });
+
+console.log(invoice.paymentRequest); // print the payment request
+console.log(invoice.paymentHash); // print the payment hash
diff --git a/package.json b/package.json
index 97fa43d..363fd88 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@getalby/lightning-tools",
-  "version": "4.2.1",
+  "version": "5.0.0",
   "description": "Collection of helpful building blocks and tools to develop Bitcoin Lightning web apps",
   "type": "module",
   "source": "src/index.ts",
@@ -36,21 +36,16 @@
     "tsc:compile": "tsc --noEmit",
     "format": "prettier --check '**/*.(md|json)' 'src/**/*.(js|ts)' 'examples/**/*.js'",
     "format:fix": "prettier --loglevel silent --write '**/*.(md|json)' 'src/**/*.(js|ts)' 'examples/**/*.js'",
-    "build:browser": "cp src/window.js dist && browserify dist/window.js > dist/index.browser.js",
     "test": "jest",
     "clean": "rm -rf dist",
-    "build": "microbundle && yarn build:browser",
+    "build": "microbundle --no-sourcemap",
     "dev": "microbundle watch",
     "prepare": "husky install"
   },
-  "dependencies": {
-    "crypto-js": "^4.1.1",
-    "light-bolt11-decoder": "^3.0.0"
-  },
+  "dependencies": {},
   "devDependencies": {
     "@commitlint/cli": "^17.7.1",
     "@commitlint/config-conventional": "^17.7.0",
-    "@types/crypto-js": "^4.1.1",
     "@types/jest": "^29.4.0",
     "@types/node": "^20.8.2",
     "@typescript-eslint/eslint-plugin": "^6.4.0",
@@ -62,6 +57,7 @@
     "husky": "^8.0.3",
     "jest": "^29.5.0",
     "jest-fetch-mock": "^3.0.3",
+    "light-bolt11-decoder": "^3.0.0",
     "lint-staged": "^14.0.0",
     "microbundle": "^0.15.1",
     "nostr-tools": "^1.17.0",
diff --git a/setupJest.ts b/setupJest.ts
index 79e0bb2..1d5b38c 100644
--- a/setupJest.ts
+++ b/setupJest.ts
@@ -1,3 +1,3 @@
-import jestFetchMock from 'jest-fetch-mock';
+import jestFetchMock from "jest-fetch-mock";
 
-jestFetchMock.enableMocks();
\ No newline at end of file
+jestFetchMock.enableMocks();
diff --git a/src/invoice.test.ts b/src/invoice.test.ts
index b20d9a8..adbc249 100644
--- a/src/invoice.test.ts
+++ b/src/invoice.test.ts
@@ -27,4 +27,15 @@ describe("Invoice", () => {
     const decodedInvoice = new Invoice({ pr: paymentRequestWithMemo });
     expect(decodedInvoice.description).toBe("Test memo");
   });
+
+  test("validate preimage", async () => {
+    const decodedInvoice = new Invoice({
+      pr: "lnbc120n1p3ecwp5pp5z8n0tzytydn57x6q0kqgfearewkx6kdh90svrkrc64azwy9jpnfqdq4f35kw6r5wdshgueqw35hqcqzpgxqyz5vqsp535pwwk083jvpnf87nl3mr4ext8q5f576s57cds72nvu7fpr037nq9qyyssqtq40wszjzs0vpaka2uckjf4xs2fu24f4vp9eev8r230m6epcp2kxdg8xztlw89p2kzkdpadujuflv6f8avgw3jhnvcxjkegdtydd95sp8hwns5",
+    });
+    expect(
+      await decodedInvoice.validatePreimage(
+        "dedbef581d83342848d99c02519053f01856add237f94437bc9bbec7bd6f6e55",
+      ),
+    ).toBe(true);
+  });
 });
diff --git a/src/invoice.ts b/src/invoice.ts
index 8ad900f..ae8e4dc 100644
--- a/src/invoice.ts
+++ b/src/invoice.ts
@@ -1,7 +1,7 @@
 import { decodeInvoice } from "./utils/invoice";
-import Hex from "crypto-js/enc-hex.js";
-import sha256 from "crypto-js/sha256.js";
 import { InvoiceArgs } from "./types";
+import { sha256 } from "./utils/sha256";
+import { fromHexString } from "./utils/hex";
 
 export default class Invoice {
   paymentRequest: string;
@@ -44,11 +44,11 @@ export default class Invoice {
     }
   }
 
-  validatePreimage(preimage: string): boolean {
+  async validatePreimage(preimage: string): Promise<boolean> {
     if (!preimage || !this.paymentHash) return false;
 
     try {
-      const preimageHash = sha256(Hex.parse(preimage)).toString(Hex);
+      const preimageHash = await sha256(fromHexString(preimage));
       return this.paymentHash === preimageHash;
     } catch {
       return false;
diff --git a/src/lightning-address.ts b/src/lightning-address.ts
index 3d019c4..3409af7 100644
--- a/src/lightning-address.ts
+++ b/src/lightning-address.ts
@@ -75,7 +75,7 @@ export default class LightningAddress {
     );
     const json = await result.json();
 
-    this.parseResponse(json.lnurlp, json.keysend, json.nostr);
+    await this.parseResponse(json.lnurlp, json.keysend, json.nostr);
   }
 
   async fetchWithoutProxy() {
@@ -99,7 +99,7 @@ export default class LightningAddress {
       nostrData = await nostrResult.json();
     }
 
-    this.parseResponse(lnurlData, keysendData, nostrData);
+    await this.parseResponse(lnurlData, keysendData, nostrData);
   }
 
   lnurlpUrl() {
@@ -249,13 +249,13 @@ export default class LightningAddress {
     return response;
   }
 
-  private parseResponse(
+  private async parseResponse(
     lnurlpData: LnUrlRawData | undefined,
     keysendData: KeySendRawData | undefined,
     nostrData: NostrResponse | undefined,
   ) {
     if (lnurlpData) {
-      this.lnurlpData = parseLnUrlPayResponse(lnurlpData);
+      this.lnurlpData = await parseLnUrlPayResponse(lnurlpData);
     }
     if (keysendData) {
       this.keysendData = parseKeysendResponse(keysendData);
diff --git a/src/utils/hex.ts b/src/utils/hex.ts
new file mode 100644
index 0000000..2151dd1
--- /dev/null
+++ b/src/utils/hex.ts
@@ -0,0 +1,5 @@
+// from https://stackoverflow.com/a/50868276
+export const fromHexString = (hexString: string) =>
+  Uint8Array.from(
+    hexString.match(/.{1,2}/g)!.map((byte) => parseInt(byte, 16)),
+  );
diff --git a/src/utils/lnurl.test.ts b/src/utils/lnurl.test.ts
index ca94013..632a2eb 100644
--- a/src/utils/lnurl.test.ts
+++ b/src/utils/lnurl.test.ts
@@ -27,7 +27,7 @@ describe("isUrl", () => {
 });
 
 describe("parseLnUrlPayResponse", () => {
-  test("min/max must be in millisats", () => {
+  test("min/max must be in millisats", async () => {
     const response = {
       status: "OK",
       tag: "payRequest",
@@ -42,7 +42,7 @@ describe("parseLnUrlPayResponse", () => {
         "79f00d3f5a19ec806189fcab03c1be4ff81d18ee4f653c88fac41fe03570f432",
       allowsNostr: true,
     };
-    const parsed = parseLnUrlPayResponse(response);
+    const parsed = await parseLnUrlPayResponse(response);
     expect(parsed.min).toBe(1000);
     expect(parsed.max).toBe(11000000000);
   });
diff --git a/src/utils/lnurl.ts b/src/utils/lnurl.ts
index 47e5b91..0fcc2f2 100644
--- a/src/utils/lnurl.ts
+++ b/src/utils/lnurl.ts
@@ -1,11 +1,9 @@
-import Hex from "crypto-js/enc-hex.js";
-import sha256 from "crypto-js/sha256.js";
-
 import type {
   LUD18ServicePayerData,
   LnUrlPayResponse,
   LnUrlRawData,
 } from "../types";
+import { sha256 } from "./sha256";
 
 const URL_REGEX =
   /((([A-Za-z]{3,9}:(?:\/\/)?)(?:[-;:&=+$,\w]+@)?[A-Za-z0-9.-]+|(?:www.|[-;:&=+$,\w]+@)[A-Za-z0-9.-]+)((?:\/[+~%/.\w-_]*)?\??(?:[-+=&;%@.\w_]*)#?(?:[\w]*))?)/;
@@ -30,7 +28,9 @@ export const isValidAmount = ({
 const TAG_PAY_REQUEST = "payRequest";
 
 // From: https://github.com/dolcalmi/lnurl-pay/blob/main/src/request-pay-service-params.ts
-export const parseLnUrlPayResponse = (data: LnUrlRawData): LnUrlPayResponse => {
+export const parseLnUrlPayResponse = async (
+  data: LnUrlRawData,
+): Promise<LnUrlPayResponse> => {
   if (data.tag !== TAG_PAY_REQUEST)
     throw new Error("Invalid pay service params");
 
@@ -45,10 +45,10 @@ export const parseLnUrlPayResponse = (data: LnUrlRawData): LnUrlPayResponse => {
   let metadataHash: string;
   try {
     metadata = JSON.parse(data.metadata + "");
-    metadataHash = sha256(data.metadata + "").toString(Hex);
+    metadataHash = await sha256(data.metadata + "");
   } catch {
     metadata = [];
-    metadataHash = sha256("[]").toString(Hex);
+    metadataHash = await sha256("[]");
   }
 
   let image = "";
diff --git a/src/utils/nostr.ts b/src/utils/nostr.ts
index f806b60..97cf0e7 100644
--- a/src/utils/nostr.ts
+++ b/src/utils/nostr.ts
@@ -1,6 +1,5 @@
-import Hex from "crypto-js/enc-hex.js";
-import sha256 from "crypto-js/sha256.js";
 import { Event, NostrResponse, ZapArgs, ZapOptions } from "../types";
+import { sha256 } from "./sha256";
 
 export async function generateZapEvent(
   { satoshi, comment, p, e, relays }: ZapArgs,
@@ -32,7 +31,7 @@ export async function generateZapEvent(
     content: comment ?? "",
   };
 
-  nostrEvent.id = getEventHash(nostrEvent);
+  nostrEvent.id = await getEventHash(nostrEvent);
   return await nostr.signEvent(nostrEvent);
 }
 
@@ -69,8 +68,8 @@ export function serializeEvent(evt: Event): string {
   ]);
 }
 
-export function getEventHash(event: Event): string {
-  return sha256(serializeEvent(event)).toString(Hex);
+export function getEventHash(event: Event): Promise<string> {
+  return sha256(serializeEvent(event));
 }
 
 export function parseNostrResponse(
diff --git a/src/utils/sha256.ts b/src/utils/sha256.ts
new file mode 100644
index 0000000..83c9753
--- /dev/null
+++ b/src/utils/sha256.ts
@@ -0,0 +1,18 @@
+// from https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto/digest
+export async function sha256(message: string | Uint8Array) {
+  // encode as UTF-8
+  const msgBuffer =
+    typeof message === "string" ? new TextEncoder().encode(message) : message;
+
+  // hash the message
+  const hashBuffer = await crypto.subtle.digest("SHA-256", msgBuffer);
+
+  // convert ArrayBuffer to Array
+  const hashArray = Array.from(new Uint8Array(hashBuffer));
+
+  // convert bytes to hex string
+  const hashHex = hashArray
+    .map((b) => b.toString(16).padStart(2, "0"))
+    .join("");
+  return hashHex;
+}
diff --git a/src/window.js b/src/window.js
deleted file mode 100644
index 915186d..0000000
--- a/src/window.js
+++ /dev/null
@@ -1,3 +0,0 @@
-// assign alby-tools exports to global window object (for index.browser.js)
-// @ts-ignore this file is created at build time
-window["lightningTools"] = require("./index.cjs");
diff --git a/tsconfig.json b/tsconfig.json
index 576273a..0bd1179 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -6,13 +6,14 @@
     "skipLibCheck": true,
     "checkJs": true,
     "allowJs": true,
-    "declarationMap": true,
+    "declarationMap": false,
     "declaration": true,
     "allowSyntheticDefaultImports": true,
     "target": "es2020",
     "rootDir": "./src",
+    "module": "ESNext",
     "moduleResolution": "node",
-    "sourceMap": true,
+    "sourceMap": false,
     "noImplicitAny": false
   },
   "include": ["src/**/*"],
diff --git a/yarn.lock b/yarn.lock
index 0d94405..1dcf19d 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1899,11 +1899,6 @@
   dependencies:
     "@babel/types" "^7.3.0"
 
-"@types/crypto-js@^4.1.1":
-  version "4.1.1"
-  resolved "https://registry.yarnpkg.com/@types/crypto-js/-/crypto-js-4.1.1.tgz#602859584cecc91894eb23a4892f38cfa927890d"
-  integrity sha512-BG7fQKZ689HIoc5h+6D2Dgq1fABRa0RbBWKBd9SP/MVRVXROflpm5fhwyATX5duFmbStzyzyycPB8qUYKDH3NA==
-
 "@types/estree@*":
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/@types/estree/-/estree-1.0.0.tgz#5fb2e536c1ae9bf35366eed879e827fa59ca41c2"
@@ -3066,11 +3061,6 @@ crypto-browserify@^3.0.0:
     randombytes "^2.0.0"
     randomfill "^1.0.3"
 
-crypto-js@^4.1.1:
-  version "4.2.0"
-  resolved "https://registry.yarnpkg.com/crypto-js/-/crypto-js-4.2.0.tgz#4d931639ecdfd12ff80e8186dba6af2c2e856631"
-  integrity sha512-KALDyEYgpY+Rlob/iriUtjV6d5Eq+Y191A5g4UqLAi8CyGP9N1+FdVbkc1SxKc2r4YAYqG8JzO2KGL+AizD70Q==
-
 css-declaration-sorter@^6.3.0:
   version "6.3.1"
   resolved "https://registry.yarnpkg.com/css-declaration-sorter/-/css-declaration-sorter-6.3.1.tgz#be5e1d71b7a992433fb1c542c7a1b835e45682ec"