DeepSeek V4.1 Flash
DeepSeek · #5 in our ranking · Fastest
DeepSeek V4.1 Flash is an open-weight mixture-of-experts model from DeepSeek, released Sep 2026, with 552B parameters (8B active per token), a 1M-token context window, and the MIT.
DeepSeek V4.1 Flash uses a causal encoder-decoder design that lets the decoder reuse a compressed KV cache, about 4x smaller than V4 Flash. It reads images and text, supports a 1M-token context, and lets you dial reasoning effort up or down.
DeepSeek V4.1 Flash specs
- Provider
- DeepSeek
- Architecture
- Mixture-of-experts
- Parameters
- 552B total · 8B active
- Context
- 1M tokens | 786K words
- License
- MIT Commercial use
- Input
- Text, Image
- Released
- Sep 2026
- Weights
- Hugging Face
Sourced from the model card on Hugging Face. Last checked 2026-10-01.
Highlights
- 8B active parameters
- About 4x smaller KV cache than V4 Flash
- MIT license
Where it fits for payment teams
- Transaction monitoring
#1 pick. Only 8B active parameters and a much smaller KV cache, so it triages thousands of alerts quickly and cheaply.
- KYC and KYB checks
#3 pick. Fast multimodal checks with an MIT license when you need throughput.
- Payments customer support
#2 pick. Very fast responses for live chat and SMS.
Harnesses in Runtime
Run DeepSeek V4.1 Flash through any of these harnesses on Runtime.
How to run DeepSeek V4.1 Flash
Download the weights
Pull deepseek-ai/DeepSeek-V4.1-Flash from Hugging Face. Check the MIT before you deploy.
Serve it in your cloud
Run it with vLLM or SGLang on your own GPUs, or use a managed provider that hosts the model.
Put it to work in Runtime
Point an agent or a single skill at the model through OpenCode, then compare it to your current model with evals.
DeepSeek V4.1 Flash FAQ
What is the context window of DeepSeek V4.1 Flash?
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DeepSeek V4.1 Flash supports a 1M-token context window (1,048,576 tokens), roughly 786K words of English text.
How many parameters does DeepSeek V4.1 Flash have?
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DeepSeek V4.1 Flash is a mixture-of-experts model with 552B total parameters, of which 8B are active per token.
Is DeepSeek V4.1 Flash free for commercial use?
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Yes. DeepSeek V4.1 Flash is released under the MIT license, which is permissive and allows commercial use and fine-tuning.
What can DeepSeek V4.1 Flash take as input?
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DeepSeek V4.1 Flash accepts text, image input and generates text.
Is DeepSeek V4.1 Flash good for transaction monitoring?
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Yes. DeepSeek V4.1 Flash is our #1 pick for transaction monitoring. Only 8B active parameters and a much smaller KV cache, so it triages thousands of alerts quickly and cheaply.
Is DeepSeek V4.1 Flash good for KYC and KYB checks?
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Yes. DeepSeek V4.1 Flash is our #3 pick for KYC and KYB checks. Fast multimodal checks with an MIT license when you need throughput.
Is DeepSeek V4.1 Flash good for payments customer support?
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Yes. DeepSeek V4.1 Flash is our #2 pick for payments customer support. Very fast responses for live chat and SMS.
Can I run DeepSeek V4.1 Flash in my own cloud with Runtime?
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Yes. Download the weights from Hugging Face (deepseek-ai/DeepSeek-V4.1-Flash) and serve them with vLLM or SGLang in your cloud, or use a managed provider that hosts the model. Runtime agents can then use DeepSeek V4.1 Flash through a harness like OpenCode, with your data staying in your environment.