# Step 3.7 Flash

A multimodal agent model that sees, reasons, and acts. Step 3.7 Flash adds native image and video understanding to the Step flash line, so one model can read a screenshot, plan a fix, and call the tools to ship it.

- **Model ID:** `stepfun/step-3.7-flash`
- **Type:** chat
- **Providers:** stepfun
- **Context window:** 256,000
- **Maximum output tokens:** 256,000
- **Pricing:** $0.2/1M input tokens, $1.15/1M output tokens
- **Canonical page:** https://vercel.com/ai-gateway/models/step-3.7-flash

## Supported parameters

Detailed capability metadata has not been reported for this model.

## Example

```ts
import { streamText } from 'ai'

const result = streamText({
  model: 'stepfun/step-3.7-flash',
  prompt: 'Why is the sky blue?'
})
```

## About

Released on May 28, 2026, Step 3.7 Flash is StepFun's flagship multimodal reasoning model. The architecture pairs the sparse mixture-of-experts language backbone from `step-3.5-flash` with a dedicated vision encoder, for roughly 198B total parameters and 11B active per token. Weights are published on GitHub, Hugging Face, and ModelScope.

Vision is built for action, not just description. Step 3.7 Flash reads product UIs, documents, charts, spreadsheets, and natural scenes, then writes code or calls tools based on what it sees. A built-in Python tool lets Step 3.7 Flash crop, zoom, and annotate images mid-task, and visual search extends coverage to long-tail entities. That composition shows up in the numbers: 95.29% on V* with Python tooling and 89.13% on HR-Bench 4K.

Agentic performance improves alongside the new modality. Step 3.7 Flash scores 76.5% on SWE-Bench Verified, 56.3% on SWE-Bench Pro, and 59.5% on Terminal-Bench 2.1, gaining about five points on SWE-Bench Pro and six points on Terminal-Bench 2.1 over `step-3.5-flash`. On search and research tasks, Step 3.7 Flash posts 75.82% on BrowseComp and 47.2% on Humanity's Last Exam with tools. StepFun trained the model to treat search as part of reasoning, favoring search planning and evidence filtering over memorized knowledge.

Through AI Gateway, you call Step 3.7 Flash with one API key and get provider routing, automatic failover, and built-in observability. Integrate via the AI SDK, the Chat Completions API, the Responses API, the Messages API, or other supported API formats.

## What to consider

Step 3.7 Flash spends tokens on both visual analysis and reasoning before answering. Multimodal requests with large images or many reasoning steps consume more output budget than plain text chat, so set token limits with headroom.

Benchmark figures come from StepFun's published evaluations, and some competitor comparisons in the release notes are self-tested. Validate on your own workload before moving production traffic. For current throughput and latency, see live metrics on this page.

## When to use

### Best For

- Multimodal agents that act on screenshots, documents, charts, and UI captures
- Agentic coding with a 76.5% SWE-Bench Verified score and strong terminal control
- Deep web and visual search workflows that combine browsing with image understanding
- Enterprise document workloads like finance, data analysis, and mixed-format reports
- GUI and phone-use automation that navigates real application interfaces

### Consider Alternatives When

- Your workload is pure text and `step-3.5-flash` covers it without the multimodal premium
- You need the highest scores available on frontier coding and research benchmarks
- Simple single-turn chat doesn't benefit from reasoning-token overhead

## Best for

- **Multimodal Agent Workflows:** Agents that act on screenshots, documents, charts, and UI captures
- **Agentic Coding:** Software tasks backed by a 76.5% SWE-Bench Verified score and strong terminal control
- **Deep Visual Search:** Research workflows that combine web browsing with image understanding
- **Enterprise Document Work:** Finance, data analysis, and mixed-format report processing
- **GUI Automation:** Phone-use and desktop tasks that navigate real application interfaces

## Consider alternatives

- **Text-Only Workloads:** `step-3.5-flash` handles pure text agents without the multimodal premium
- **Maximum Benchmark Headroom:** Larger frontier models still lead on the hardest coding and research suites
- **Simple Single-Turn Chat:** Reasoning and vision tokens add overhead that lightweight conversation doesn't need

## Frequently asked questions

### What architecture does Step 3.7 Flash use?

Step 3.7 Flash pairs a sparse mixture-of-experts language backbone with a dedicated vision encoder, totaling roughly 198B parameters with 11B active per token. See https://platform.stepfun.ai/docs/en/guides/models/step-3.7-flash for details.

### What visual inputs can Step 3.7 Flash understand?

Step 3.7 Flash natively understands images and video, including product UIs, documents, charts, spreadsheets, and natural scenes. A built-in Python tool lets Step 3.7 Flash crop, zoom, and annotate images during a task.

### How does Step 3.7 Flash differ from `step-3.5-flash`?

Step 3.7 Flash adds a vision encoder for native image and video understanding, which `step-3.5-flash` lacks. Step 3.7 Flash also improves agentic coding, gaining about five points on SWE-Bench Pro and six points on Terminal-Bench 2.1 over its predecessor.

### What is the context window for Step 3.7 Flash?

Step 3.7 Flash supports a context window of 256K tokens and a max output of 256K tokens per request.

### How well does Step 3.7 Flash perform on benchmarks?

Step 3.7 Flash scores 76.5% on SWE-Bench Verified, 56.3% on SWE-Bench Pro, 59.5% on Terminal-Bench 2.1, and 75.82% on BrowseComp in StepFun's published evaluations. Vision results include 95.29% on V* with Python tooling and 89.13% on HR-Bench 4K.

### How do I call Step 3.7 Flash through AI Gateway?

Use the model identifier `stepfun/step-3.7-flash` with the AI SDK, the Chat Completions API, the Responses API, the Messages API, or another supported API format. You authenticate with an AI Gateway API key, and no StepFun account is needed.

### Does AI Gateway support Zero Data Retention for Step 3.7 Flash?

Zero Data Retention is not currently available for this model. Zero Data Retention is offered on a per-provider basis. See https://vercel.com/docs/ai-gateway/capabilities/zdr for details.

## Links

- [Model page](https://vercel.com/ai-gateway/models/step-3.7-flash)
- [AI Gateway documentation](https://vercel.com/docs/ai-gateway)
- [Provider model documentation](https://platform.stepfun.ai/docs/en/guides/models/step-3.7-flash)