Short answer: WhatsApp leads in Malaysia (used monthly by about 91% of internet users) and Indonesia, LINE in Thailand (56 million monthly users, about 83% of internet users), Zalo in Vietnam (78 to 81 million monthly users) and Facebook Messenger in the Philippines (about 62 million users), where Viber is also common. Plan your sales channels and languages per market.
The leading app in each market
A note on the numbers: some are the share of internet users who use an app each month, some are the company's own monthly active users, and the Philippines figure is Meta's advertising reach. They answer "which app do people here use?" well, but they aren't one comparable scale.
Malaysia: WhatsApp
WhatsApp is the default for both personal and business chat. DataReportal's Digital 2025 Malaysia report found about 90.7% of internet users use it every month. Telegram and Messenger are used alongside it, often for groups and community channels. Customers write in Malay, English and Chinese, often mixing them in one message.
Indonesia: WhatsApp
WhatsApp is the leading chat app in survey data (GWI, as summarised by Sinch). Meta doesn't publish an advertising reach figure for WhatsApp, so there's no exact user count, but shops, resellers and service businesses run on WhatsApp numbers. Reply in Bahasa Indonesia, not Malay: the two are close but not the same.
Thailand: LINE
LINE is to Thailand what WhatsApp is to Malaysia. DataReportal's Digital 2026 Thailand report, using LINE's own figures, puts it at 56 million monthly active users, about 82.6% of internet users. Many Thai buyers simply won't add a WhatsApp number, so a LINE account is close to essential. Messages are usually in Thai, with polite particles (ค่ะ / ครับ) that matter for tone.
Vietnam: Zalo
Zalo, made by Vietnam's VNG, dominates there. DataReportal's Digital 2026 Vietnam report gives 78.3 million monthly active users, and VNG's results for the second quarter of 2026 reported about 81 million. Its users are almost all in Vietnam, so it matters for that market only. Facebook Messenger is also widely used.
The Philippines: Facebook Messenger
Messenger leads, helped by how central Facebook is in the Philippines. DataReportal's Messenger figures, from Meta's advertising tools, put its reach at about 61.8 million users in January 2025. Viber is the strong second in survey data. English and Filipino (Tagalog) are both fine for business chat.
What this means for your sales team
- Pick channels per market. A WhatsApp-only setup misses most Thai and Vietnamese buyers.
- Plan for languages. Malay, Indonesian, Thai, Vietnamese and Filipino are five different languages. Translation built into the chat window saves a lot of copy and paste (see our chat translation guide).
- Keep the accounts together. A team covering several markets ends up with WhatsApp, LINE, Zalo and Messenger accounts. Working them in one place stops chats slipping through.
BlackCat SCRM covers WhatsApp, Telegram, LINE, Messenger, TikTok, Zalo and X in one window. Translation and AI replies work on WhatsApp, Telegram, LINE and Messenger. Zalo, TikTok and X currently open with unread counts and alerts only, and Viber isn't supported.
Sources
- DataReportal, Digital 2025: Malaysia (WhatsApp monthly use among internet users).
- DataReportal, Digital 2026: Thailand (LINE monthly active users, from LINE).
- DataReportal, Digital 2026: Vietnam (Zalo monthly active users); VNG, results for Q2 2026, as reported in the press.
- DataReportal, Messenger users, stats and trends (Philippines reach, January 2025).
- Sinch, The most popular messaging apps by country (GWI survey data for Indonesia and the Philippines).
FAQ
What is the most used messaging app in Southeast Asia?
It depends on the country: WhatsApp in Malaysia and Indonesia, LINE in Thailand, Zalo in Vietnam and Facebook Messenger in the Philippines.
Do I need LINE to sell in Thailand?
In practice, yes. LINE reaches about 83% of Thai internet users, and many buyers prefer it to WhatsApp.
Can BlackCat SCRM translate Zalo chats?
Not yet. Zalo opens in BlackCat with unread counts, pop-up alerts and message sounds, but translation and AI replies work on WhatsApp, Telegram, LINE and Messenger.
