diff --git a/README.md b/README.md
index 5616a5e..57c55a9 100644
--- a/README.md
+++ b/README.md
@@ -1,12 +1,20 @@
 # Sugoi-web
-Chrome extension to translate Japanese web novels with Sugoi Offline Translation Server (https://www.patreon.com/mingshiba) or DeepL API.
+Extension for Chromium-based browsers and Firefox to translate Japanese web novels with Sugoi Offline Translation Server (https://www.patreon.com/mingshiba) or DeepL API.
 
-**Installation:**
+**Installation for Chromium-based browsers:**
 1. Download the *Source code (zip)* archive from Releases
 2. Unpack the archive
 3. Open extensions page (*chrome://extensions/*)
 4. Enable **Developer Mode**
-5. Add extension using the "Load Unpacked" button
+5. Press "Load Unpacked" button and select folder with *manifest.json*
+
+**Installation for Firefox:**
+1. Download the *Source code (zip)* archive from Releases
+2. Unpack the archive
+3. Delete *manifest.json*
+4. Rename *manifest-firefox.json* to *manifest.json*
+5. Open extensions page (*about:debugging#/runtime/this-firefox*)
+6. Press "Load Temporary Add-on" button and select *manifest.json*
 
 **Using with Sugoi:**
 1. Open *{Sugoi folder} / backendServer / Program-Backend / Sugoi-Japanese-Translator / offlineTranslation*
diff --git a/js/background.js b/js/background.js
index 40a5f03..a65732e 100644
--- a/js/background.js
+++ b/js/background.js
@@ -61,7 +61,6 @@ class DeepL
 			data += '&text=' + encodeURIComponent(lines[i]);
 		}
 
-		/*
 		const response = await fetch(this.url, {
 			method: 'POST',
 			body: data,
@@ -70,15 +69,6 @@ class DeepL
 				'Content-Type': 'application/x-www-form-urlencoded',
 			}
 		});
-		*/
-		const response = await fetch('https://api-free.deepl.com/v2/translate', {
-			method: 'POST',
-			body: data,
-			headers: {
-				'Authorization': 'DeepL-Auth-Key 3e598917-623e-c1dc-1163-cad97a555430:fx',
-				'Content-Type': 'application/x-www-form-urlencoded',
-			},
-		});
 
 		const result = [];
 
@@ -101,7 +91,14 @@ class DeepL
 
 function button_toggle(tab_id, enable)
 {
-	chrome.action.enable(tab_id);
+	if (chrome.action)
+	{
+		chrome.action.enable(tab_id);
+	}
+	else
+	{
+		chrome.browserAction.enable(tab_id);
+	}
 	/*
 	chrome.action.setIcon({
 		path: enable ? 'images/icon32.png' : 'images/icon32_off.png'
@@ -227,12 +224,17 @@ async function processExternalMessage(request, sender)
 	return response;
 }
 
+function is_firefox()
+{
+	return typeof browser !== 'undefined';
+}
+
 chrome.runtime.onMessage.addListener((request, sender, sendResponse) => {
-	processMessage(request, sender).then(sendResponse);
-	return true;
+	const promise = processMessage(request, sender).then(sendResponse);
+	return is_firefox ? promise : true;
 });
 
 chrome.runtime.onMessageExternal.addListener((request, sender, sendResponse) => {
-	processExternalMessage(request, sender).then(sendResponse);
-	return true;
+	const promise = processExternalMessage(request, sender).then(sendResponse);
+	return is_firefox ? promise : true;
 });
\ No newline at end of file
diff --git a/js/classes/ChromeApi.js b/js/classes/ChromeApi.js
index 01d5b84..5d5e405 100644
--- a/js/classes/ChromeApi.js
+++ b/js/classes/ChromeApi.js
@@ -78,7 +78,10 @@ class ChromeApi
 			config.deepl_texts_per_request = parseInt(config.deepl_texts_per_request);
 		}
 
-		return this.storageSet({config: config});
+		// firefox workaround, otherwise saved empty object
+		const data = JSON.parse(JSON.stringify(config));
+
+		return this.storageSet({config: data});
 	}
 
 	/**
diff --git a/js/classes/TranslatorSugoi.js b/js/classes/TranslatorSugoi.js
index ad94c2d..1ea8e92 100644
--- a/js/classes/TranslatorSugoi.js
+++ b/js/classes/TranslatorSugoi.js
@@ -7,7 +7,7 @@ class TranslatorSugoi extends Translator
 	 * @type {string}
 	 * @private
 	 */
-	_url = 'http://127.0.0.1';
+	_url = 'http://localhost';
 
 	/**
 	 *
diff --git a/manifest-firefox.json b/manifest-firefox.json
new file mode 100644
index 0000000..1f0f6b2
--- /dev/null
+++ b/manifest-firefox.json
@@ -0,0 +1,65 @@
+{
+	"name": "Sugoi Web Translation",
+	"version": "1.0.8",
+
+	"manifest_version": 2,
+
+	"description": "Sugoi/DeepL Web Translation",
+	"icons": {
+		"128": "images/s128.png",
+		"16": "images/s16.png",
+		"48": "images/s48.png"
+	},
+
+	"browser_action": {
+		"default_icon": {
+			"32": "images/s32.png"
+		},
+		"default_title": "Sugoi/DeepL Web Translation",
+		"default_popup": "popup/action.html"
+	},
+
+	"permissions": [
+		"storage",
+		"tabs",
+		"http://localhost/*",
+		"https://api-free.deepl.com/v2/*",
+		"https://api.deepl.com/v2/*"
+	],
+	"background": {
+		"scripts": ["js/background.js"]
+	},
+
+	"content_scripts":[
+		{
+			"js": [
+				"js/vendor/jquery-3.4.1.min.js",
+				"js/classes/Utilities.js",
+
+				"js/classes/Translator.js",
+				"js/classes/TranslatorSugoi.js",
+				"js/classes/TranslatorDeepL.js",
+				"js/classes/TranslatorLine.js",
+
+				"js/classes/proxy/Proxy.js",
+				"js/classes/proxy/ProxySyosetu.js",
+				"js/classes/proxy/ProxyKakuyomu.js",
+				"js/classes/proxy/ProxyUnavailable.js",
+
+				"js/classes/ChromeApi.js",
+				"js/classes/Config.js",
+				"js/classes/UI.js",
+
+				"js/main.js"
+			],
+			"matches": [
+				"*://*.syosetu.com/*",
+				"*://syosetu.com/*",
+				"*://*.kakuyomu.jp/*",
+				"*://kakuyomu.jp/*"
+			],
+			"run_at": "document_end",
+			"all_frames": true
+		}
+	]
+}
\ No newline at end of file
diff --git a/manifest.json b/manifest.json
index f85ab0f..1be8fa6 100644
--- a/manifest.json
+++ b/manifest.json
@@ -1,11 +1,11 @@
 {
 	"name": "Sugoi Web Translation",
-	"version": "1.0.7",
+	"version": "1.0.8",
 
 	"manifest_version": 3,
 	"incognito": "split",
 
-	"description": "",
+	"description": "Sugoi/DeepL Web Translation",
 	"icons": {
 		"128": "images/s128.png",
 		"16": "images/s16.png",
@@ -16,7 +16,7 @@
 		"default_icon": {
 			"32": "images/s32.png"
 		},
-		"default_title": "Sugoi Web Translation",
+		"default_title": "Sugoi/DeepL Web Translation",
 		"default_popup": "popup/action.html"
 	},