Thunderbird extensions

SaaY 4 appsUpdated Jan 6, 2026

1
LanguageTool
Like
An AI-powered proofreading tool supports over 20 languages, offering free and premium versions with extensive grammar checks across multiple apps.
Cost / License
Freemium
Open Source
Application typeApplication types
Grammar Checker
AI Writing Tool
Platforms
Mac
Windows
Linux
Online
iPhone
iPad
Microsoft Edge
ONLYOFFICE
Google Chrome
Microsoft Outlook
Safari
Visual Studio Code
Microsoft Word
Eclipse
TinyMCE
Google Docs
Thunderbird
Vim
Cloudron
Sublime Text
GNU Emacs
Opera
Gmail
LibreOffice
Apache OpenOffice
Mozilla Firefox
LibreOffice - Writer
+2
SaaY ’s note
https://addons.thunderbird.net/en-US/thunderbird/addon/grammar-and-spell-checker/
2
Proton Calendar
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Your calendar is a record of your life. Proton Calendar helps keep it private.
Cost / License
Freemium
Proprietary
Application type
Calendar App
Platforms
Online
Android
iPhone
Android Tablet
iPad
Android Auto
Tor
+1
SaaY ’s note
https://addons.thunderbird.net/en-US/thunderbird/addon/proton-calendar-toolbar-button/
3
Proton Mail
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Secure Swiss-based email with end-to-end encryption and zero third-party access. Available across devices, offering a free version to promote privacy.
Cost / License
Freemium
Open Source
Application typeApplication types
WebMail Provider
Email Client
Platforms
Mac
Windows
Linux
Online
Android
iPhone
iPad
Snapcraft
Flathub
Tor
OpenAPK
+9
SaaY ’s note
https://addons.thunderbird.net/en-US/thunderbird/addon/proton-mail-toolbar-button/
4
WhatsApp
Like
Free messaging without SMS fees, web sync, and multimedia sharing, supporting group and video chats, available on iPhone, Android, and desktop.
Cost / License
Freemium
Proprietary
Application typeApplication types
Instant Messenger
Video Calling App
Platforms
Mac
Windows
Online
Android
iPhone
Android Tablet
iPad
Apple Watch
Android Auto
Android Wear
Apple Car Play
+6
SaaY ’s note
https://addons.thunderbird.net/en-US/thunderbird/addon/whatsapp-quick-access/