DeepSeek

DeepSeek is an AI chat assistant from the Chinese company DeepSeek, Inc. The service is available at chat.deepseek.com and through mobile apps for iOS and Android; an account can be created without entering payment details. Unlike most major competitors such as ChatGPT, Claude, or Gemini, the vendor's official product page does not list a paid "Plus" or "Pro" tier for the chat: DeepSeek positions itself as a consistently free assistant, funded instead through a separately billed API aimed at developers.

What the chat assistant does

At its core is a text-based chat that, per the vendor, offers both a fast standard model and an explicit reasoning mode ("DeepThink"), in which the model visibly writes out its step-by-step reasoning before answering. It also includes a web search feature that pulls current information into answers, plus file upload for documents and images. The vendor markets its current model generation as "DeepSeek-V4.1-Flash," citing improvements in text and agent behavior along with native multimodal vision understanding.

Model architecture and open weights

Technically, DeepSeek's models rely on a Mixture-of-Experts architecture: for the publicly documented DeepSeek-V3, the official GitHub repository states 671 billion total parameters, of which only around 37 billion actually activate per processed token – an approach that reduces compute cost without capping overall model size. Its context window is 128,000 tokens. What has drawn particular industry attention is that the surrounding code is released under the permissive MIT license, and the model weights themselves are published under a separate license that, per the vendor, permits commercial use as well. Anyone who prefers not to use the hosted version can download the open weights from platforms like Hugging Face and run them on their own infrastructure or with common inference frameworks – an option that closed models like GPT or Gemini do not offer.

API for custom applications

For integration into custom software, DeepSeek offers an API at platform.deepseek.com compatible with the OpenAI and Anthropic request formats. According to the official pricing documentation, two models are available: a faster, cheaper "DeepSeek-Flash" with vision support, and the more capable "DeepSeek-V4-Pro" without vision support; billing is based on consumed tokens and distinguishes between peak and off-peak hours, with off-peak requests priced considerably lower per the vendor. This API is a separate, independently billed product and is not tied to the free chat access.

Data handling and server location

DeepSeek is a Chinese company, and its chat service is registered with the relevant Chinese authorities per its legal notice. Anyone considering DeepSeek for professional or regulated use should review their own requirements around data processing outside the EU or the US before entering confidential content – a consideration several organizations and public bodies raise generally regarding Chinese AI services. As with any AI chat service, general caution around sharing sensitive or personal data in a conversation still applies.

Who DeepSeek fits

Anyone wanting to try a capable chat assistant with no payment obligation and no subscription limits will find DeepSeek an easy starting point, particularly for coding and math tasks, where the DeepThink reasoning mode reportedly performs especially well per the vendor. Developers looking for an affordable, OpenAI-compatible API, or who prefer to self-host their models, benefit additionally from the openly released model weights. Anyone required by privacy or compliance policy to use only EU- or US-based vendors should check beforehand whether DeepSeek fits their specific use case.