What are some alternatives?
When comparing simperium and Amazon SQS, you can also consider the following products
GUN - Self-hosted Firebase.
Apache Kafka - Apache Kafka is an open-source message broker project developed by the Apache Software Foundation written in Scala.
Firebase - Firebase is a cloud service designed to power real-time, collaborative applications for mobile and web.
RabbitMQ - RabbitMQ is an open source message broker software.
Pusher - Pusher is a hosted API for quickly, easily and securely adding scalable realtime functionality via WebSockets to web and mobile apps.
ZeroMQ - ZeroMQ is a high-performance asynchronous messaging library.