DeepSeek
Free chatbot from Chinese lab DeepSeek, running its open-weight V4-series models with DeepThink reasoning, web search and file reading on web and mobile.
Evaluation
What to know
Best for
- Students and hobbyists who want a capable free reasoning model
- Developers comparing open-weight models before self-hosting
- Budget-conscious builders using the API for high-volume tasks
Not ideal for
- Companies with strict data-residency or government compliance rules
- Users researching Chinese politics or other censored subjects
- Anyone needing a polished ecosystem of plugins and integrations
Key features
- DeepSeek-V4.1-Flash model with native image understanding
- DeepThink mode that shows step-by-step reasoning
- Built-in web search toggle for current information
- File and image uploads for reading documents in chat
- Open-weight model family plus a low-cost OpenAI-compatible API
Pros
- Strong reasoning model at no cost for consumer use
- Open weights let privacy-conscious teams self-host instead
- API pricing undercuts most frontier providers, especially off-peak
Cons
- Data handled under Chinese jurisdiction, which rules it out for many organizations
- Politically sensitive topics are censored
- Servers have historically slowed or refused new sessions at peak demand
ToolifyNav verdict
Few chat assistants offer this much reasoning depth at no charge. The chat app asks for no subscription, DeepThink handles multi-step math and code problems well, and the open weights give technical teams a route to run the same models on their own hardware. The trade-offs are not about capability. Jurisdiction, censorship and occasional capacity crunches will disqualify it for regulated businesses and for some research topics. Individuals who understand those limits get a frontier-class assistant without a bill; organizations should treat the hosted app with caution and evaluate the self-hosted path instead.
About
About DeepSeek
DeepSeek is the Hangzhou-based AI lab, funded by the quantitative hedge fund High-Flyer, that unsettled the industry in January 2025 when its R1 reasoning model matched leading Western models on several benchmarks and shipped with open weights. The consumer chatbot at chat.deepseek.com is the simplest way to use those models, and there is no paid consumer subscription: the web app and the iOS and Android apps are free.
The current default is DeepSeek-V4.1-Flash, which the company says brings broad improvements in text and agent tasks plus native image understanding. Two toggles shape a chat. DeepThink switches on visible step-by-step reasoning for math, code and logic problems, and Search lets the model pull in live web results. You can attach documents and images for the model to read. The model lineage — V3, R1, V3.1, V3.2, V4, V4.1 — is documented on the company site, and many of these weights are published for anyone to run locally.
Developers who want to build on the models use the separate API, which is OpenAI- and Anthropic-compatible and billed per million tokens, with off-peak discounts. Privacy is the main caution: data is processed under Chinese jurisdiction, and several governments have restricted the app on official devices. Content on politically sensitive topics is also filtered.
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