Step3

Name: Step3-321B-A38B
Author: StepFunAI

Multimodal model

Step3-321B-A38B

Release date: 2025-07-31Updated: 2025-08-04Views: 819

Live demo GitHub Hugging Face Compare

Parameters

321B

Context length

64K

Multilingual

Supported

Reasoning ability

3/5

Step3-321B-A38B is an AI model published by StepFunAI, released on 2025-07-31, for Multimodal model, with 321B parameters, and 64K context length, requiring about 642GB storage, with a 82.90 score on AIME2025.

Data sourced primarily from official releases (GitHub, Hugging Face, papers), then benchmark leaderboards, then third-party evaluators. Learn about our data methodology

Step3

Model basics

Reasoning traces

No data

Thinking modes

Standard Mode (Default)Thinking Mode

Context length

64K tokens

Max output length

No data

Model type

Multimodal model

Modality (in / out)

Text → Video

Release date

2025-07-31

Model file size

642GB

MoE architecture

Yes

Total params / Active params

321B / 38B

Knowledge cutoff

No data

Step3

Open source & experience

Code license

Apache 2.0

Weights license

Apache 2.0- Commercial use permitted

GitHub repo

github.com/stepfun-ai/Step3

Hugging Face

huggingface.co/stepfun-ai/step3

Live demo

stepfun.ai/chats/new

Step3

Official resources

Paper

DataLearnerAI blog

N/A

Step3

API details

API speed

4/5

No public API pricing yet.

Step3

Benchmark Results

Step3 currently shows benchmark results led by LiveCodeBench (101 / 250, score 67.10), AIME2025 (88 / 215, score 82.90), MMMU (37 / 74, score 74.20). This page also consolidates core specs, context limits, and API pricing so you can evaluate the model from benchmark results and deployment constraints together.