LINE

Is LINE safe?

LINE is safer than its reputation suggests on one point and weaker on several others. The strong point is encryption: most private chats are end-to-end encryptedEnd-to-end encryptionEncryption in which only the sender and the recipient can read a message. The company running the service cannot see its content.More in the glossary by default, so LY Corporation cannot read them. The weak points are a serious 2023 breach, repeated government guidance, heavy advertising use of personal data, and LINE's central role in Japan's scam epidemic. We score it 44/100, below WhatsApp (67) and above WeChat (36).

For most users in Japan, Taiwan and Thailand, the practical question is how to use LINE carefully, because nearly everyone they know is on it.

What happened in the LINE data breach?

On 14 September 2023 attackers got into LY's systems through a PC belonging to an employee of a contractor that worked for both LY and NAVER Cloud, the Korean company whose parent co-owns LY. The PC was infected with malware. Because LY and NAVER Cloud shared an authentication system for staff, the attackers could move into the former LINE Corporation's internal network. LY's security team spotted the activity on 17 October.

LY's final count, published in February 2024, was 519,506 records: 302,980 about users, 86,211 about business partners and 130,315 about staff. Among the user records were 22,239 entries of "information about communications privacy", meaning interactions between specific users. LY said no bank or card details and no chat messages stored in the LINE app were involved.

The ministry of internal affairs and communications (MIC) issued administrative guidance in March 2024 and again in April 2024, the second time asking for a review of security governance across the whole group "including the parent company". Japan's privacy commission issued its own recommendation. That pressure is why LY moved to cut its technical ties with NAVER, set a March 2026 deadline to separate systems and networks from NAVER Cloud, and closed LINE Pay, which NAVER had built. LY says it submitted its final reports on these measures in July 2026.

How strong is LINE's encryption?

Letter Sealing, LINE's own end-to-end protocol, has been on by default since 2016 and cannot be turned off since 2021. It covers text, location, photos, videos, voice messages and files, plus 1-to-1 voice and video calls. Group chats are covered only up to 50 members. A second version replaced the original in 2019 after researchers reported weaknesses through LINE's bug bounty programme.

The gaps matter. Open Chat rooms, chats with official accounts, group calls, LINE Meeting, albums and notes are protected only in transit. Adding a translation bot to a chat ends end-to-end protection from that point on. And backups to iCloud or Google Drive are stored in readable form, unless you pay for LY Premium Backup.

There were also two smaller incidents. In November 2024 an albums error showed some users the wrong thumbnails, which earned MIC guidance in March 2025. In July 2026 LY admitted that three LINE games had sent internal user IDs of about 6.1 million people to an outside advertising tool since 2022, without telling them, and MIC issued guidance again.

What does LINE do with your data?

LINE is free because it sells advertising, and its App Store label says so. User ID and device ID are used to track you across other companies' apps. Location, email, phone number, search history and browsing history are linked to you for third-party advertising. LY's privacy policy says it matches data from partners, such as hashed phone numbers and advertising IDs, with its own to target ads and official account messages. In some countries it may use parts of your messages for ads if you give extra consent.

LINE scams in Japan

Japan's police recorded 9,538 social media investment frauds in 2025, with losses of about ¥127 billion, up 46% on 2024. At a briefing in August 2026, LY said LINE was the contact tool in 96% of these cases. Victims usually meet scammers through Instagram, YouTube or ads, then get moved into a LINE chat. LY has a permanent anti-fraud team, but it says it can do little once a victim is talking to a scammer privately.

How to use LINE more safely

1. Do not join investment groups or follow "advisers" who invite you from ads or social media.
2. In privacy settings, limit who can find and add you by ID or phone number.
3. Keep sensitive talk out of Open Chat and group calls, which are not end-to-end encryptedEnd-to-end encryptionEncryption in which only the sender and the recipient can read a message. The company running the service cannot see its content.More in the glossary.
4. Set a backup PIN, and remember that iCloud and Google Drive backups are not end-to-end encrypted.
5. Review ad settings in LY's Privacy Center and switch off what you do not want.

How we scored it

Privacy (35) is LINE's weakest factor, because of advertising tracking and data matching with partners. Security (50) balances default end-to-end encryptionEnd-to-end encryptionEncryption in which only the sender and the recipient can read a message. The company running the service cannot see its content.More in the glossary against the 2023 breach and the gaps in coverage. Scams (40) and regulatory record (45) reflect LINE's role in Japan's fraud wave and four rounds of ministry guidance in three years.