Chinese AI company StepFun has launched the STEPX, a smartphone built around an agent-native operating system that can execute tasks across nearly 100 third-party services.
StepFun has unveiled what it describes as an agent-first smartphone, positioning artificial intelligence not as a helper layered on top of a handset, but as the core of the device. The Chinese company first introduced the STEPX brand, its agent system and its operating software in Shanghai on July 13, saying conventional mobile software was not designed for autonomous task execution.
At the centre of the product is Step AOS 1.0, an operating system StepFun says was built specifically for AI agents. The company claims the software combines elements of Android, Linux and real-time operating systems, while breaking functions such as messaging, applications, files and settings into modular components that the agent can invoke directly through the Model Context Protocol, or MCP. Users are presented with both the familiar app grid and a separate agent interface.
The built-in assistant, Amoo, is designed to manage both personal context and task execution. StepFun says it maintains one memory for facts, habits and preferences, and another for what it has learned about completing actions. Routine commands, such as setting alarms, are processed on a smaller on-device model, sometimes offline, while more complex requests are sent to a larger cloud model. A secondary MiniLED screen on the back of the phone displays what the agent is doing.
The company says nearly 100 services and products, including Alipay, Tencent, Ctrip, Didi and Meituan, have signed on to Amoo, although payments, travel bookings and content creation still take place on those platforms rather than inside a single StepFun-controlled system. That is a notable contrast with the screen-reading and simulated-click method used by Doubao.
StepFun, founded in 2023 by former Microsoft vice president Jiang Daxin, is also a model developer in its own right. Its Step 5 Preview model, released in September, has 600 billion parameters, with 27 billion active at a time, and can process up to 1 million tokens in a single input. The company’s smaller Step 3.5 Flash model is open source under the Apache 2.0 licence. The STEPX device is priced at 3,999 yuan and includes 12 months of the STEPX Token Plan, which offers 100 billion tokens a month; StepFun has not yet disclosed the cost after the first year.
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