Whatsapp

WhatsApp is a free messaging and calling app for individuals who want to stay in touch with friends and family using their phone number.

Key capabilities include:

• End-to-end encrypted messaging for text, photos, videos, audio, and documents, plus group chats and real-time location sharing
• Voice and video calls over Wi‑Fi or mobile data, including group calling, to avoid SMS and international texting charges
• Privacy-focused controls such as disappearing messages (auto-delete after 7 days), delete for everyone (within 60 minutes), and view once photos and videos
• Conversation utilities like starred messages, reply to specific messages in groups, voice message transcripts, and chat summaries

Pricing: Free (data charges may apply via carrier)

What makes it notable is its combination of phone-number-based signup, broad availability across Android, iOS, Desktop, and Web, and end-to-end encryption for private conversations and calls, plus built-in features like live location tracking and message expiration.