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Signal also does historical synchronization between devices. It bootstraps the history from another device. It also has search which can be done locally. Telegram is, by design, capable of being accessed by 3rd parties (beyond governments). iMessage is capable of being accessed by 3rd parties via iCloud backups, which is an opt-in situation.

Be aware, wechat sends every message with geolocation to the authorities in real time. It is more critical than ever that we be aware of the mechanisms in the systems we build and use -- else dystopia awaits.