Step 3.7 Flash
Step 3.7 Flash is StepFun's flagship multimodal reasoning model, a sparse MoE with 11B active parameters and native image and video understanding. It supports a context window of 256K tokens and a max output of 256K tokens per request.
import { streamText } from 'ai'
const result = streamText({ model: 'stepfun/step-3.7-flash', prompt: 'Why is the sky blue?'})Playground
Try out Step 3.7 Flash by StepFun. Usage is billed to your team at API rates. Free users (those who haven't made a payment) get $5 of credits every 30 days.
Step 3.7 Flash
Ask Step 3.7 Flash anything to try it out.
Providers
Route requests across multiple providers. Copy a provider slug to set your preference. Visit the docs for more info. Using a provider means you agree to their terms, listed under Legal.
| Provider |
|---|
StepFun | 256K | 8.9s | 163tps | $0.20/M | $1.15/M | Read:$0.04/M Write:— | — | — | +2 | 05/28/2026 |
P50 throughput on live AI Gateway traffic, in tokens per second (TPS). Visit the docs for more info.
P50 time to first token (TTFT) on live AI Gateway traffic, in milliseconds. View the docs for more info.
Direct request success rate on AI Gateway and per-provider. Visit the docs for more info.
More models by StepFun
| Model |
|---|
| 262K | 0.3s | 134tps | $0.09/M | $0.30/M | Read:$0.02/M Write:— | — | — | +1 |  | 01/29/2026 |
About Step 3.7 Flash
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 When Choosing a Provider
- Configuration: 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.
- Configuration: 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.
- Zero Data Retention: AI Gateway does not currently support Zero Data Retention for this model. See the documentation for models that support ZDR.
- Authentication: AI Gateway authenticates requests using an API key or OIDC token. You do not need to manage provider credentials directly.
When to Use Step 3.7 Flash
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 When
- Text-Only Workloads:
step-3.5-flashhandles 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
Conclusion
Step 3.7 Flash extends the Step flash line from text agents to agents that see. You get native image and video understanding, stronger coding scores, and tool use that spans terminals, browsers, and visual inputs. Route Step 3.7 Flash through AI Gateway for failover, observability, and one key across the whole catalog.