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Kimi K2 Thinking

Ready
model path:accounts/fireworks/models/kimi-k2-thinking

Kimi K2 Thinking is the latest, most capable version of open-source thinking model. Starting with Kimi K2, it was built as a thinking agent that reasons step-by-step while dynamically invoking tools. It sets a new state-of-the-art on Humanity’s Last Exam (HLE), BrowseComp, and other benchmarks by dramatically scaling multi-step reasoning depth and maintaining stable tool-use across 200–300 sequential calls. At the same time, K2 Thinking is a native INT4 quantization model with 256k context window, achieving lossless reductions in inference latency and GPU memory usage.

Kimi K2 Thinking API Features

On-demand Deployment

Docs

On-demand deployments allow you to use Kimi K2 Thinking on dedicated GPUs with Fireworks' high-performance serving stack with high reliability and no rate limits.

Metadata

State
Ready
Created on
6 NOV, 2025
Kind
Base model
Provider
Moonshot AI

Specifications

Calibrated
Yes
Mixture-of-Experts
Yes
Parameters
1.02T

Supporting Functionality

Fine-tuning
Not Supported
Serverless
Not Supported
Context Length
262k tokens
Function Calling
Supported
Embeddings
Not Supported
Rerankers
Not Supported
Supporting image input
Not Supported

Kimi K2 Thinking FAQs

Kimi K2 Thinking is the latest version of Moonshot AI’s open-source “thinking model,” designed for advanced reasoning tasks. It interleaves step-by-step chain-of-thought reasoning with autonomous tool use, achieving strong performance across benchmarks like HLE, AIME25, and BrowseComp.