Question: I'm looking for a lightweight messaging app that doesn't drain my phone's battery and offers customizable message templates.

If you're seeking a lightweight messaging app that won't flatten your battery and that lets you customize templates for common messages, FireTexts could be for you. It uses AI and the GPT-4 large language model technology to generate messages for different circumstances, like birthday messages and flirtations. It's lightweight, so it won't take up much storage space or flatten your battery. FireTexts is available on iOS and Android and lets you add context for more personalized messages and responds quickly.

Another option is AutoResponder, which can link to services like WhatsApp, Facebook Messenger and Telegram. The app automates responses based on rules you set up, so you don't have to do as much work. It's good for personal and professional use, with a PRO plan that adds abilities like custom answer replacements and welcome messages.

If you want a more powerful messaging tool, check out Texts. This app collects messages from services like iMessage, WhatsApp and Telegram into a unified inbox for better organization and productivity. Features include chat summaries, draft responses generated with ChatGPT and a customizable user interface. It's designed with privacy in mind, encrypting messages and not storing user data.