diff --git a/packages/nextjs/src/server.ts b/packages/nextjs/src/server.ts
index 0a568de..bd69e25 100644
--- a/packages/nextjs/src/server.ts
+++ b/packages/nextjs/src/server.ts
@@ -22,8 +22,8 @@ export async function trackEvent(
 
 function getHeaders(req?: NextIncomingMessage): Headers | undefined {
   if (req) {
-    // we only need the user-agent header
     return new Headers({
+      'accept-language': req.headers['accept-language'] ?? '',
       'user-agent': req.headers['user-agent'] ?? '',
     });
   }
diff --git a/packages/node/src/index.ts b/packages/node/src/index.ts
index 2c87252..ddd8b8e 100644
--- a/packages/node/src/index.ts
+++ b/packages/node/src/index.ts
@@ -2,6 +2,8 @@ import { AptabaseOptions } from './types';
 
 export { AptabaseOptions };
 
+const isDebug = process.env.NODE_ENV === 'development';
+
 export function init(appKey: string, options?: AptabaseOptions) {
   globalThis.__APTABASE__ = { appKey, options };
 }
@@ -15,18 +17,15 @@ export async function trackEvent(
   props?: Record<string, string | number | boolean>,
 ): Promise<void> {
   const { appKey } = globalThis.__APTABASE__ || {};
-
   if (!appKey) return Promise.resolve();
 
-  const userAgent = req.headers.get('user-agent') ?? '';
-
   const body = JSON.stringify({
     timestamp: new Date().toISOString(),
     sessionId: 'CHANGE-THIS',
     eventName: eventName,
     systemProps: {
-      isDebug: true,
-      locale: 'en',
+      isDebug,
+      locale: extractLocale(req.headers.get('accept-language')),
       appVersion: '',
       sdkVersion: globalThis.__APTABASE_SDK_VERSION__ ?? `aptabase-node@${process.env.PKG_VERSION}`,
     },
@@ -37,7 +36,7 @@ export async function trackEvent(
     const response = await fetch('http://localhost:3000/api/v0/event', {
       method: 'POST',
       headers: {
-        'User-Agent': userAgent,
+        'User-Agent': req.headers.get('user-agent') ?? '',
         'Content-Type': 'application/json',
         'App-Key': appKey,
       },
@@ -53,3 +52,17 @@ export async function trackEvent(
     console.warn(`Failed to send event "${eventName}": ${e}`);
   }
 }
+
+function extractLocale(locale: string | null): string | null {
+  if (!locale) {
+    return null;
+  }
+
+  const languageLocales = locale.split(',');
+  const firstLanguageLocale = languageLocales[0];
+  if (!firstLanguageLocale) {
+    return null;
+  }
+  const [language] = firstLanguageLocale.split(';');
+  return language || null;
+}
diff --git a/packages/web/src/index.ts b/packages/web/src/index.ts
index 43851fa..fdfef36 100644
--- a/packages/web/src/index.ts
+++ b/packages/web/src/index.ts
@@ -1,13 +1,13 @@
 export type AptabaseOptions = {
   host?: string;
   appVersion?: string;
-  __sdkVersion?: string;
 };
 
+const locale = navigator?.languages && navigator?.languages.length ? navigator?.languages[0] : navigator?.language;
+const isDebug = location?.hostname === 'localhost';
+
 let _appKey = '';
 let _apiUrl = '';
-let _locale = '';
-let _isDebug = false;
 let _options: AptabaseOptions | undefined;
 
 const _hosts: { [region: string]: string } = {
@@ -41,26 +41,25 @@ export function init(appKey: string, options?: AptabaseOptions) {
 
   const baseUrl = getBaseUrl(parts[1], options);
   _apiUrl = `${baseUrl}/api/v0/event`;
-
-  if (typeof location !== 'undefined') {
-    _isDebug = location.hostname === 'localhost';
-  }
-
-  if (typeof navigator !== 'undefined') {
-    _locale = navigator.languages && navigator.languages.length ? navigator.languages[0] : navigator.language;
-  }
 }
 
 export function trackEvent(eventName: string, props?: Record<string, string | number | boolean>) {
-  if (!_appKey || typeof window === 'undefined' || !window.fetch) return;
+  if (!_appKey) return;
+
+  if (typeof window === 'undefined' || !window.fetch) {
+    console.warn(
+      `Aptabase: this call to "trackEvent" requires a browser environment. Did you import from the wrong package?`,
+    );
+    return;
+  }
 
   const body = JSON.stringify({
     timestamp: new Date().toISOString(),
     sessionId: 'CHANGE-THIS',
     eventName: eventName,
     systemProps: {
-      isDebug: _isDebug,
-      locale: _locale,
+      isDebug,
+      locale,
       appVersion: _options?.appVersion ?? '',
       sdkVersion: globalThis.__APTABASE_SDK_VERSION__ ?? `aptabase-web@${process.env.PKG_VERSION}`,
     },
diff --git a/packages/web/src/session.ts b/packages/web/src/session.ts
deleted file mode 100644
index 59b92b5..0000000
--- a/packages/web/src/session.ts
+++ /dev/null
@@ -1,23 +0,0 @@
-export function newSessionId() {
-  if (typeof crypto !== "undefined" && crypto && crypto.randomUUID) {
-    return crypto.randomUUID();
-  }
-
-  return [
-    randomStr(8),
-    randomStr(4),
-    randomStr(4),
-    randomStr(4),
-    randomStr(12),
-  ].join("-");
-}
-
-const characters = "abcdefghijklmnopqrstuvwxyz0123456789";
-const charactersLength = characters.length;
-function randomStr(len: number) {
-  let result = "";
-  for (let i = 0; i < len; i++) {
-    result += characters.charAt(Math.floor(Math.random() * charactersLength));
-  }
-  return result;
-}