Step 3.5 Flash is Free in Kilo

What’s more fun than Stepfun?

We’re always looking for ways to put the most capable models directly into your development workflow with zero friction. Today, we’re thrilled to announce that Step 3.5 Flash, Stepfun’s powerful open-weight model, is completely free to use inside Kilo Code and KiloClaw for a limited time.

Why Step 3.5 Flash?

If you haven’t been tracking Stepfun’s latest releases, now is the time to start paying attention. The landscape of open models is moving at breakneck speed, and Step 3.5 Flash is proving exactly why open weights are becoming a standard for day-to-day agentic work. The lab has continued to improve this release for speed and efficiency—so even if you’ve tried the initial release of 3.5 Flash, we recommend giving the current version a whirl.

When you’re running an AI agent, you need a model that balances speed with deep reasoning and flawless tool execution. Step 3.5 Flash delivers on all fronts. It’s fast, highly steerable, and uniquely optimized for the autonomous coding tasks that make up your daily grind—from navigating file trees and reading documentation to running terminal commands and debugging complex logic.

Agents have to reason fast. Powered by 3-way Multi-Token Prediction (MTP-3), Step 3.5 Flash achieves a generation throughput of 100 to 300 tokens per second in typical usage.

Don’t just take our word for it: Step 3.5 Flash has been aggressively dominating the OpenClaw leaderboard on OpenRouter, securing its place at the very top. It has the proven reasoning chops you need when you’re trusting an AI to manipulate your codebase or just keep your agents running ‘round the clock.

This isn’t just about the strength of the model, it’s also about the strength of the open-source community. The model had over 133k downloads on Hugging Face last month, and the lab is just getting started.

It’s all about efficiency without losing sight of reasoning. Or, as the Stepfun team put it in a paper back in February: “By redefining the efficiency frontier, Step 3.5 Flash provides a high-density foundation for deploying sophisticated agents in real-world industrial environments….comparable to frontier models such as GPT-5.2 xHigh and Gemini 3.0 Pro.”

Free in Kilo Code and KiloClaw

We want you to experience this level of top-tier, open-source power without watching your token balance drain. For a limited time, we’ve worked with Stepfun to cover the bill.

You can access Step 3.5 Flash for exactly zero cost across our core toolkit:

• Kilo Code: Hook it up to your daily coding flow for rapid-fire chat, highly accurate inline edits, and fast code generation.

• KiloClaw: Let it loose as your primary agent. Because Step 3.5 Flash is so fast and capable, it thrives in KiloClaw’s autonomous, multi-step environment where intelligent tool execution is critical.

How to Get Started

There are no hoops to jump through. Simply open up Kilo Code or KiloClaw, select Step 3.5 Flash (FREE) from the model dropdown menu, and start building.

We don’t know exactly how long we’ll keep the faucet open on this one, so take advantage of it while it’s here. Update your clients, fire up an agent, and see what the top of the OpenClaw leaderboard actually feels like in practice, with your personal KiloClaw firing on all cylinders for basically zero cost.