Google Allo Alternatives
Google Allo was discontinued by Google, but don't worry we have compiled a list of Google Allo Alternatives:

Wickr
Wickr is a free end-to-end encrypted text, video, picture and voice messenger with full sender control.

ICQ
CQ is one of the oldest instant messengers. First developed by the Israeli company Mirabilis, sold to AOL, sold again and currenly owned by the Russian “mail.ru” group (known for one of the largest social networks). ICQ has been redesigned and is totally different from the “old ICQ”. It’s available for almost every platform: Web, Desktop, Mobile and even via WAP.

WeChat is a complete mobile communication and private social networking app.

Threema
Threema is a new mobile messaging app that puts security first. With true end-to-end encryption, you can rest assured that only you and the intended recipient can read your messages.

Line
LINE is a Japanese proprietary application for instant messaging on smartphones and PCs. Line users exchange text messages, graphics, video and audio media, make free VoIP calls, and hold free audio or video conferences.

ChatSecure
ChatSecure is a free and open source messaging app that features OTR encryption over XMPP. You can connect to your existing accounts on Facebook or Google, create new accounts on public XMPP servers(including via Tor), or even connect to your own server for extra security.

Trillian
Trillian is an instant messaging app that works on phones, tablets, and desktops while keeping your chats neatly synchronized between all of them! We think conversation should be easily shared between all of your devices, not trapped as text messages on your phone. Here’s how we do it:
• INSTANT MESSAGING: Your unique Trillian username can be used to send unlimited messages free of charge. Trillian uses your existing data plan and/or WiFi.

Conversations
Conversations is a privacy focused, open source XMPP Texting [Jabber] client for Android 4.0+ smart phones with wife-approved easy encryption [OTR, OMEMO, or GPG].

Facebook Messenger
Facebook Messenger is a faster way to message. Reach friends right on their phones, get and send messages fast, message everyone at once and more.

Wire
Wire is the most secure collaboration platform featuring messenger, voice, video, conference calls, file-sharing, and external collaboration –all protected by the most secure end-to-end-encryption.

Hangouts
Hangouts is a messaging app that lets you send and receive messages, photos and more, and even start free video and voice calls – one to one or with a group!
“Hangouts” are places used to facilitate group video chat (with a maximum of 10 people participating in a single Hangout at any point in time).

WhatsApp Messenger
WhatsApp Messenger is a cross-platform mobile messaging app which allows you to exchange messages without having to pay for SMS. WhatsApp Messenger is available for iPhone, BlackBerry, Android, Windows Phone and Nokia and yes, those phones can all message each other! Because WhatsApp Messenger uses the same internet data plan that you use for email and web browsing, there is no cost to message and stay in touch with your friends.