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About

Step 3.5 Flash is an advanced open source foundation language model engineered for frontier reasoning and agentic capabilities with exceptional efficiency, built on a sparse Mixture of Experts (MoE) architecture that selectively activates only about 11 billion of its ~196 billion parameters per token to deliver high-density intelligence and real-time responsiveness. Its 3-way Multi-Token Prediction (MTP-3) enables generation throughput in the hundreds of tokens per second for complex multi-step reasoning chains and task execution, and it supports efficient long contexts with a hybrid sliding window attention approach that reduces computational overhead across large datasets or codebases. It demonstrates robust performance on benchmarks for reasoning, coding, and agentic tasks, rivaling or exceeding many larger proprietary models, and includes a scalable reinforcement learning framework for consistent self-improvement.

About

Trinity Large Thinking is a frontier open source reasoning model developed by Arcee AI, designed specifically for complex, multi-step problem solving and autonomous agent workflows that require long-horizon planning and tool use. Built on a sparse Mixture-of-Experts architecture with roughly 400 billion total parameters but only about 13 billion active per token, the model achieves high efficiency while maintaining strong reasoning performance across tasks such as mathematical problem solving, code generation, and multi-step analysis. It introduces extended chain-of-thought reasoning capabilities, allowing the model to generate intermediate “thinking traces” before producing final answers, which improves accuracy and reliability in complex scenarios. Trinity Large Thinking supports a very large context window of up to 262K tokens, enabling it to process long documents, maintain state across extended interactions, and operate effectively in continuous agent loops.

Platforms Supported

Windows
Mac
Linux
Cloud
On-Premises
iPhone
iPad
Android
Chromebook

Platforms Supported

Windows
Mac
Linux
Cloud
On-Premises
iPhone
iPad
Android
Chromebook

Audience

Developers, researchers, and AI engineers who want a powerful open source foundational AI model capable of fast, deep reasoning, coding assistance, and agentic task execution

Audience

Developers and enterprises building autonomous AI agents that need a high-performance, open-source reasoning model for complex, multi-step workflows

Support

Phone Support
24/7 Live Support
Online

Support

Phone Support
24/7 Live Support
Online

API

Offers API

API

Offers API

Screenshots and Videos

Screenshots and Videos

Pricing

Free
Free Version
Free Trial

Pricing

Free
Free Version
Free Trial

Reviews/Ratings

Overall 0.0 / 5
ease 0.0 / 5
features 0.0 / 5
design 0.0 / 5
support 0.0 / 5

This software hasn't been reviewed yet. Be the first to provide a review:

Review this Software

Reviews/Ratings

Overall 0.0 / 5
ease 0.0 / 5
features 0.0 / 5
design 0.0 / 5
support 0.0 / 5

This software hasn't been reviewed yet. Be the first to provide a review:

Review this Software

Training

Documentation
Webinars
Live Online
In Person

Training

Documentation
Webinars
Live Online
In Person

Company Information

StepFun
Founded: 2023
China
static.stepfun.com/blog/step-3.5-flash/

Company Information

Arcee AI
Founded: 2023
United States
www.arcee.ai/blog/trinity-large-thinking

Alternatives

MiMo-V2-Flash

MiMo-V2-Flash

Xiaomi Technology

Alternatives

Kimi K2 Thinking

Kimi K2 Thinking

Moonshot AI
GLM-5.1

GLM-5.1

Zhipu AI
GLM-4.5

GLM-4.5

Z.ai
GLM-4.5

GLM-4.5

Z.ai

Categories

Categories

Integrations

Claude Opus 4.6
GitHub
Hugging Face
ModelScope
OpenClaw
OpenRouter
Visual Studio Code
arXiv

Integrations

Claude Opus 4.6
GitHub
Hugging Face
ModelScope
OpenClaw
OpenRouter
Visual Studio Code
arXiv
Claim Step 3.5 Flash and update features and information
Claim Step 3.5 Flash and update features and information
Claim Trinity-Large-Thinking and update features and information
Claim Trinity-Large-Thinking and update features and information