Step 3.5 Flash

Step 3.5 Flash is StepFun's flash lane for quick multimodal reasoning and coding assistance. It is the first version of its line in the registry. It has a context window of 256,000 tokens and a maximum output of 256,000 tokens. It accepts text and returns text. It supports reasoning mode and tool calling. The weights are open. Pricing starts at $0.09 per million input tokens and $0.30 per million output tokens, with cached input at $0.02 per million tokens. It is served by 14 hosts. Knowledge cutoff is January 2025.

First version of its line in the registry.

Range across the hosts that serve it: up to $0.10 per 1M input tokens.

• ·256k token context and output windows
• ·Open weights with reasoning mode
• ·Tool calling supported
• ·Low cost: $0.09/M input, $0.30/M output
• ·Served by 14 hosts

• Reach for it for quick multimodal reasoning tasks
• Reach for it for coding assistance
• Reach for it for long-context text processing
• Reach for it for tool-using agent workflows

14 hosts serve this model at the price above · the maker's documentation

The registry keeps the six most recent versions of a line. Older ones stay in the file and can be surfaced without a rebuild.

What is the context window size?

The context window is 256,000 tokens, and the maximum output is also 256,000 tokens.

Does it support tool calling?

Yes, it supports tool calling and reasoning mode. It accepts text and returns text.

Is the model open weights?

Yes, the weights are open. It is served by 14 hosts and pricing starts at $0.09 per million input tokens.