diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..1b6457c
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,4 @@
+{
+  "editor.formatOnSave": true,
+  "editor.defaultFormatter": "esbenp.prettier-vscode"
+}
diff --git a/README.md b/README.md
index d1d8e08..db0be8d 100644
--- a/README.md
+++ b/README.md
@@ -10,6 +10,31 @@ This JavaScript SDK for the Alby OAuth2 Wallet API and the Nostr Wallet Connect
 npm install @getalby/sdk
 ```
 
+or
+
+```
+yarn add @getalby/sdk
+```
+
+or for use without any build tools:
+
+```html
+<script type="module">
+  import { webln } from "https://esm.sh/@getalby/js-sdk@3.0.0"; // jsdelivr.net, skypack.dev also work
+
+  // use webln normally...
+  (async () => {
+    const nwc = new webln.NostrWebLNProvider({
+      nostrWalletConnectUrl: YOUR_NWC_URL,
+    });
+    await nwc.enable();
+    const balanceResponse = await nwc.getBalance();
+    console.log("Wallet balance", balanceResponse.balance);
+    nwc.close();
+  })();
+</script>
+```
+
 **This library relies on a global fetch() function which will work in browsers and node v18.x or newer.** (In older versions you have to use a polyfill.)
 
 ## Content
@@ -127,6 +152,7 @@ catch (e) {
 ```
 
 #### React Native (Expo)
+
 Look at our [NWC React Native Expo Demo app](https://github.com/getAlby/nwc-react-native-expo) for how to use NWC in a React Native expo project.
 
 #### For Node.js
@@ -249,7 +275,7 @@ const authClient = new auth.OAuth2User({
   }, // initialize with existing token
 });
 
-const authUrl = authClient.generateAuthURL({
+const authUrl = await authClient.generateAuthURL({
   code_challenge_method: "S256",
   // authorizeUrl: "https://getalby.com/oauth"  endpoint for authorization (replace with the appropriate URL based on the environment)
 });
diff --git a/examples/boostagram.js b/examples/boostagram.js
index 70fd57d..1ce3712 100644
--- a/examples/boostagram.js
+++ b/examples/boostagram.js
@@ -25,7 +25,7 @@ const authClient = new auth.OAuth2User({
 });
 
 console.log(`Open the following URL and authenticate the app:`);
-console.log(authClient.generateAuthURL());
+console.log(await authClient.generateAuthURL());
 console.log("----\n");
 
 const code = await rl.question("Code: (localhost:8080?code=[THIS CODE]: ");
diff --git a/examples/decode-invoice.js b/examples/decode-invoice.js
index e2771aa..2109d51 100644
--- a/examples/decode-invoice.js
+++ b/examples/decode-invoice.js
@@ -20,7 +20,7 @@ const authClient = new auth.OAuth2User({
 });
 
 console.log(`Open the following URL and authenticate the app:`);
-console.log(authClient.generateAuthURL());
+console.log(await authClient.generateAuthURL());
 console.log("----\n");
 
 const code = await rl.question("Code: (localhost:8080?code=[THIS CODE]: ");
diff --git a/examples/invoices.js b/examples/invoices.js
index 03ef621..0e4c25c 100644
--- a/examples/invoices.js
+++ b/examples/invoices.js
@@ -18,7 +18,7 @@ const authClient = new auth.OAuth2User({
 });
 
 console.log(`Open the following URL and authenticate the app:`);
-console.log(authClient.generateAuthURL());
+console.log(await authClient.generateAuthURL());
 console.log("----\n");
 
 const code = await rl.question("Code: (localhost:8080?code=[THIS CODE]: ");
diff --git a/examples/keysends.js b/examples/keysends.js
index 4db7783..fd76078 100644
--- a/examples/keysends.js
+++ b/examples/keysends.js
@@ -25,7 +25,7 @@ const authClient = new auth.OAuth2User({
 });
 
 console.log(`Open the following URL and authenticate the app:`);
-console.log(authClient.generateAuthURL());
+console.log(await authClient.generateAuthURL());
 console.log("----\n");
 
 const code = await rl.question("Code: (localhost:8080?code=[THIS CODE]: ");
diff --git a/examples/nwc/get-balance.js b/examples/nwc/get-balance.js
index 48e45d1..1e77cd3 100644
--- a/examples/nwc/get-balance.js
+++ b/examples/nwc/get-balance.js
@@ -9,9 +9,9 @@ import { webln as providers } from "../../dist/index.module.js";
 
 const rl = readline.createInterface({ input, output });
 
-const nwcUrl = await rl.question(
-  "Nostr Wallet Connect URL (nostr+walletconnect://...): ",
-);
+const nwcUrl =
+  process.env.NWC_URL ||
+  (await rl.question("Nostr Wallet Connect URL (nostr+walletconnect://...): "));
 rl.close();
 
 const webln = new providers.NostrWebLNProvider({
diff --git a/examples/oauth2-public-callback_pkce_s256.mjs b/examples/oauth2-public-callback_pkce_s256.mjs
index 7311c8d..f91c941 100644
--- a/examples/oauth2-public-callback_pkce_s256.mjs
+++ b/examples/oauth2-public-callback_pkce_s256.mjs
@@ -1,14 +1,29 @@
 import { auth, Client } from "../dist/index.module.js";
 import express from "express";
 
+if (!process.env.CLIENT_ID || !process.env.CLIENT_SECRET) {
+  throw new Error("Please set CLIENT_ID and CLIENT_SECRET");
+}
+
 const app = express();
 
 const authClient = new auth.OAuth2User({
   client_id: process.env.CLIENT_ID,
   client_secret: process.env.CLIENT_SECRET,
   callback: "http://localhost:8080/callback",
-  scopes: ["invoices:read", "account:read", "balance:read", "invoices:create", "invoices:read", "payments:send"],
-  token: {access_token: undefined, refresh_token: undefined, expires_at: undefined} // initialize with existing token
+  scopes: [
+    "invoices:read",
+    "account:read",
+    "balance:read",
+    "invoices:create",
+    "invoices:read",
+    "payments:send",
+  ],
+  token: {
+    access_token: undefined,
+    refresh_token: undefined,
+    expires_at: undefined,
+  }, // initialize with existing token
 });
 
 const client = new Client(authClient);
@@ -29,7 +44,7 @@ app.get("/callback", async function (req, res) {
 });
 
 app.get("/login", async function (req, res) {
-  const authUrl = authClient.generateAuthURL({
+  const authUrl = await authClient.generateAuthURL({
     state: STATE,
     code_challenge_method: "S256",
   });
@@ -52,20 +67,20 @@ app.get("/value4value", async function (req, res) {
 });
 
 app.get("/make-invoice", async function (req, res) {
-  const result = await client.createInvoice({amount: 1000});
+  const result = await client.createInvoice({ amount: 1000 });
   res.send(result);
 });
 
-app.get("/bolt11/:invoice", async function(req, res) {
-  const result = await client.sendPayment({invoice: req.params.invoice});
+app.get("/bolt11/:invoice", async function (req, res) {
+  const result = await client.sendPayment({ invoice: req.params.invoice });
   res.send(result);
 });
 
-app.get('/keysend/:destination', async function(req, res) {
+app.get("/keysend/:destination", async function (req, res) {
   const result = await client.keysend({
     destination: req.params.destination,
     amount: 10,
-    memo: req.query.memo
+    memo: req.query.memo,
   });
   res.send(result);
 });
diff --git a/examples/send-to-ln-address.js b/examples/send-to-ln-address.js
index 568f5e3..307b46e 100644
--- a/examples/send-to-ln-address.js
+++ b/examples/send-to-ln-address.js
@@ -19,7 +19,7 @@ const authClient = new auth.OAuth2User({
 });
 
 console.log(`Open the following URL and authenticate the app:`);
-console.log(authClient.generateAuthURL());
+console.log(await authClient.generateAuthURL());
 console.log("----\n");
 
 const code = await rl.question("Code: (localhost:8080?code=[THIS CODE]: ");
diff --git a/examples/webhooks.js b/examples/webhooks.js
index e8f50d2..a2cf29a 100644
--- a/examples/webhooks.js
+++ b/examples/webhooks.js
@@ -25,7 +25,7 @@ const authClient = new auth.OAuth2User({
 });
 
 console.log(`Open the following URL and authenticate the app:`);
-console.log(authClient.generateAuthURL());
+console.log(await authClient.generateAuthURL());
 console.log("----\n");
 
 const code = await rl.question("Code: (localhost:8080?code=[THIS CODE]: ");
diff --git a/package.json b/package.json
index 43955f1..f1aabda 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@getalby/sdk",
-  "version": "2.7.0",
+  "version": "3.0.0",
   "description": "The SDK to integrate with Nostr Wallet Connect and the Alby API",
   "repository": "https://github.com/getAlby/js-sdk.git",
   "bugs": "https://github.com/getAlby/js-sdk/issues",
@@ -33,20 +33,17 @@
     "prepack": "yarn run build",
     "test": "jest",
     "clean": "rm -rf dist",
-    "build:browser": "cp src/window.js dist && browserify dist/window.js > dist/index.browser.js",
-    "build": "microbundle && yarn build:browser",
+    "build": "microbundle --no-sourcemap",
     "dev": "microbundle watch",
     "prepare": "husky install"
   },
   "dependencies": {
-    "crypto-js": "^4.1.1",
     "nostr-tools": "^1.17.0",
     "events": "^3.3.0"
   },
   "devDependencies": {
     "@commitlint/cli": "^17.7.1",
     "@commitlint/config-conventional": "^17.7.0",
-    "@types/crypto-js": "^4.1.1",
     "@types/jest": "^29.5.5",
     "@types/node": "^20.8.6",
     "@typescript-eslint/eslint-plugin": "^6.3.0",
diff --git a/src/OAuth2User.ts b/src/OAuth2User.ts
index be52dc4..6196a25 100644
--- a/src/OAuth2User.ts
+++ b/src/OAuth2User.ts
@@ -1,5 +1,4 @@
-import CryptoJS from "crypto-js";
-import { buildQueryString, basicAuthHeader } from "./utils";
+import { buildQueryString, basicAuthHeader, toHexString } from "./utils";
 import {
   OAuthClient,
   AuthHeader,
@@ -75,6 +74,7 @@ export class OAuth2User implements OAuthClient {
     if (this._refreshAccessTokenPromise) {
       return this._refreshAccessTokenPromise;
     }
+    // eslint-disable-next-line no-async-promise-executor
     this._refreshAccessTokenPromise = new Promise(async (resolve, reject) => {
       try {
         const refresh_token = this.token?.refresh_token;
@@ -109,7 +109,7 @@ export class OAuth2User implements OAuthClient {
         resolve({ token });
         this._tokenEvents.emit("tokenRefreshed", this.token);
       } catch (error) {
-        console.log(error);
+        console.error(error);
         reject(error);
         this._tokenEvents.emit("tokenRefreshFailed", error);
       } finally {
@@ -140,7 +140,9 @@ export class OAuth2User implements OAuthClient {
       throw new Error("client_id is required");
     }
     if (!client_secret && !code_verifier) {
-      throw new Error("either client_secret is required, or code should be generated using a challenge");
+      throw new Error(
+        "either client_secret is required, or code should be generated using a challenge",
+      );
     }
     if (!callback) {
       throw new Error("callback is required");
@@ -171,23 +173,16 @@ export class OAuth2User implements OAuthClient {
     return { token };
   }
 
-  generateAuthURL(options?: GenerateAuthUrlOptions): string {
+  async generateAuthURL(options?: GenerateAuthUrlOptions): Promise<string> {
     if (!options) {
       options = {};
     }
-    console.log(options);
     const { client_id, callback, scopes } = this.options;
     if (!callback) throw new Error("callback required");
     if (!scopes) throw new Error("scopes required");
     let code_challenge_method;
     if (options.code_challenge_method === "S256") {
-      const code_verifier = CryptoJS.lib.WordArray.random(64);
-      this.code_verifier = code_verifier.toString();
-      this.code_challenge = CryptoJS.SHA256(this.code_verifier)
-        .toString(CryptoJS.enc.Base64)
-        .replace(/\+/g, "-")
-        .replace(/\//g, "_")
-        .replace(/\=+$/, "");
+      await this._generateS256Challenge();
       code_challenge_method = "S256";
     } else if (
       options.code_challenge_method === "plain" &&
@@ -220,4 +215,24 @@ export class OAuth2User implements OAuthClient {
       Authorization: `Bearer ${this.token.access_token}`,
     };
   }
+
+  private async _generateS256Challenge() {
+    const codeVerifierBytes = crypto.getRandomValues(new Uint8Array(64));
+    this.code_verifier = toHexString(codeVerifierBytes);
+
+    // from https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto/digest
+    const hashBuffer = await crypto.subtle.digest(
+      "SHA-256",
+      new TextEncoder().encode(this.code_verifier),
+    );
+    const hashArray = new Uint8Array(hashBuffer);
+
+    // from https://stackoverflow.com/a/45313868
+    // TODO: consider using Buffer.from(hashBuffer).toString("base64") in NodeJS
+    this.code_challenge = btoa(String.fromCharCode(...hashArray))
+      // from https://gist.github.com/jhurliman/1250118?permalink_comment_id=3194799
+      .replace(/\+/g, "-")
+      .replace(/\//g, "_")
+      .replace(/=+$/, "");
+  }
 }
diff --git a/src/types.ts b/src/types.ts
index 3534627..160d0ec 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -47,7 +47,7 @@ export type GenerateAuthUrlOptions = { authorizeUrl?: string } & (
 
 export abstract class OAuthClient implements AuthClient {
   abstract token?: Token;
-  abstract generateAuthURL(options: GenerateAuthUrlOptions): string;
+  abstract generateAuthURL(options: GenerateAuthUrlOptions): Promise<string>;
   abstract requestAccessToken(code?: string): Promise<{ token: Token }>;
   abstract getAuthHeader(
     url?: string,
diff --git a/src/utils.ts b/src/utils.ts
index 314fc19..eb1245a 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -12,3 +12,7 @@ export function basicAuthHeader(
 ) {
   return `Basic ${btoa(`${client_id}:${client_secret}`)}`;
 }
+
+// from https://stackoverflow.com/a/50868276
+export const toHexString = (bytes: Uint8Array) =>
+  bytes.reduce((str, byte) => str + byte.toString(16).padStart(2, "0"), "");
diff --git a/src/webln/OauthWeblnProvider.ts b/src/webln/OauthWeblnProvider.ts
index 9230007..74318af 100644
--- a/src/webln/OauthWeblnProvider.ts
+++ b/src/webln/OauthWeblnProvider.ts
@@ -13,7 +13,7 @@ export class OauthWeblnProvider {
   client: Client;
   auth: OAuthClient;
   oauth: boolean;
-  subscribers: Record<string, (payload: any) => void>;
+  subscribers: Record<string, (payload: unknown) => void>;
   isExecuting: boolean;
 
   constructor(options: { auth: OAuthClient }) {
@@ -28,7 +28,7 @@ export class OauthWeblnProvider {
     this.subscribers[name] = callback;
   }
 
-  notify(name: string, payload?: any) {
+  notify(name: string, payload?: unknown) {
     const callback = this.subscribers[name];
     if (callback) {
       callback(payload);
@@ -45,7 +45,7 @@ export class OauthWeblnProvider {
     if (isBrowser()) {
       try {
         this.isExecuting = true;
-        const result = await this.openAuthorization();
+        await this.openAuthorization();
       } finally {
         this.isExecuting = false;
       }
@@ -123,12 +123,14 @@ export class OauthWeblnProvider {
     }
   }
 
-  openAuthorization() {
+  async openAuthorization() {
     const height = 700;
     const width = 600;
     const top = window.outerHeight / 2 + window.screenY - height / 2;
     const left = window.outerWidth / 2 + window.screenX - width / 2;
-    const url = this.auth.generateAuthURL({ code_challenge_method: "S256" });
+    const url = await this.auth.generateAuthURL({
+      code_challenge_method: "S256",
+    });
 
     return new Promise((resolve, reject) => {
       const popup = window.open(
diff --git a/src/window.js b/src/window.js
deleted file mode 100644
index dd73d5a..0000000
--- a/src/window.js
+++ /dev/null
@@ -1,3 +0,0 @@
-// assign alby-sdk exports to global window object (for index.browser.js)
-// @ts-ignore
-window["albySDK"] = require("./index.cjs");
diff --git a/tsconfig.json b/tsconfig.json
index 5e063b5..207ce4a 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -6,12 +6,13 @@
     "skipLibCheck": true,
     "checkJs": true,
     "allowJs": true,
-    "declarationMap": true,
+    "declarationMap": false,
     "declaration": true,
     "allowSyntheticDefaultImports": true,
     "target": "es2020",
+    "module": "ESNext",
     "rootDir": "./src",
-    "sourceMap": true,
+    "sourceMap": false,
     "moduleResolution": "node"
   },
   "include": ["src/**/*"],
diff --git a/yarn.lock b/yarn.lock
index 3755a76..ddbbb40 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2021,11 +2021,6 @@
   dependencies:
     "@babel/types" "^7.20.7"
 
-"@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"
@@ -3256,11 +3251,6 @@ 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"