DeepSeek is a chat assistant from the Chinese AI lab DeepSeek. It offers a free web app and mobile apps, plus a paid API that developers use to build their own tools. It first drew wide attention for reasoning models that tackle maths, logic, and code step by step while costing far less to run than many Western equivalents.

Because it is developed in China, it is also a reminder that not every assistant comes with the same privacy and content rules. That is worth understanding before you paste in anything you would not want to leave your computer.

What it does well

DeepSeek's strength is careful, visible reasoning. Ask it to solve a maths problem, walk through a proof, or debug a function, and it will often show its working, which makes mistakes easier to spot. Developers like it for an API that is inexpensive relative to its quality, and some open-weight versions can be run locally.

For everyday writing and summarizing it is perfectly capable, though it is less polished than the most popular assistants for creative or conversational work. Students often use it to check their own working on a problem: solve it yourself first, then compare, rather than letting the tool do the thinking.

How to use it well

Give it the full problem, including constraints, and ask it to show its steps so you can check the logic. For code, paste the error message and the surrounding function rather than only a description. When the answer matters, test the result instead of trusting the explanation, since reasoning that reads well can still be wrong. If a long answer drifts, ask it to restate the conclusion in one line and list the assumptions it made.

What to watch

Think about where your data goes. The public chat is fine for learning and brainstorming, but keep personal, medical, financial, and work-confidential material out of it unless you have checked the terms and are comfortable with them. Check the official DeepSeek site for current models and API pricing.

If you prefer an assistant from a US or European provider, our ChatGPT overview is a common starting point.