What Is DeepSeek? How to Use the Free AI Tool from China and What It Can Do in 2026
機械翻訳 / Machine-translated
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AI Friends
2026年4月21日・18分で読める
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DeepSeek is a free AI chat tool developed in 2023 by a Chinese AI company. Like ChatGPT, it can answer questions and write text, but it has attracted significant attention for its exceptionally high ability to solve math and programming problems.
DeepSeek's greatest feature is that it is completely free to use, despite delivering world-class performance.
Many AI tools require a monthly subscription fee, but DeepSeek's web chat version is available for free immediately after registration.
Its development cost was only around 6–8 million USD — remarkably low compared to other AI systems (which often cost hundreds of millions or more).
DeepSeek has several models (types of AI), and as of April 2026, the two flagship models are DeepSeek-V3 and DeepSeek-R1.
V3 is a standard model suited for a wide range of tasks, while R1 is a model specialized for reasoning (working through a problem step by step to arrive at an answer).
It also supports Japanese, allowing for natural conversation in the language.
DeepSeek offers many useful features to help with studying and work. Here are five standout features as of 2026.
DeepSeek is exceptionally strong at mathematics.
It has recorded an astonishing accuracy rate of 96.7% on problems at the level of the International Mathematical Olympiad (IMO) — a math competition for high school students from around the world.
It can handle middle school and high school math homework, as well as university-level calculus and linear algebra.
When you enter a formula, it walks you through each step of the calculation, so you can learn not just the answer but also how to solve the problem.
If you instruct it to "write a program that does ○○," it will automatically write code in languages such as Python or JavaScript.
Even programming beginners can get working code simply by describing in plain language what they want to build.
If you paste code that contains an error (a bug), it will identify what is wrong and suggest a corrected version.
The DeepSeek-R1 model specializes in reasoning — working through complex problems step by step to reach an answer.
For example, it can accurately solve logic puzzles like: "The combined age of Person A and Person B is 50. In 10 years, Person A will be the same age Person B is now. How old are they?" — thinking through each step methodically.
It is also useful for developing business strategies and analyzing the root causes of complex problems.
Paste a long document or article and ask it to "summarize this," and it will condense the key points into a brief overview.
You can quickly grasp the content of academic papers, news articles, and meeting minutes.
It can also work in reverse — expanding a short note into a full-length piece of writing.
For instance, if you instruct it to "write an 800-character report on environmental issues," it will generate a well-structured piece.
The 2026 version of DeepSeek has multimodal capabilities, meaning it can understand not just text but also images.
For example, if you upload a photo of a math problem, it will read and solve the problem from the image.
It can also explain graphs and charts, decipher handwritten notes, and describe what appears in photographs.
Even beginners can get started with DeepSeek in just three steps. Here we explain the basic usage of the free web chat version.
First, go to DeepSeek's official website at chat.deepseek.com.
First-time users need to create a free account.
Enter your email address or phone number and receive a verification code.
Once you enter the verification code, registration is complete.
You can also log in with a Google account or Microsoft account.
Once you log in, the chat screen will appear.
You can select the model you want to use from the top of the screen.
If it's your first time, DeepSeek-V3 is recommended — it's the standard model capable of handling a wide range of questions.
If you want to solve complex math or programming problems, choose DeepSeek-R1.
The free version lets you try both models.
Type your question or instruction in the input field at the bottom of the screen.
For example, you can ask things like:
Just ask naturally, as you would in normal conversation.
Press Enter, and the AI will respond within seconds.
To upload an image, click the paperclip icon next to the input field and select an image file.
DeepSeek has both convenient features and points to be aware of. Before you start using it, here are the key pros and cons.
DeepSeek is ideal for people who want to solve logical problems or write code. Specifically, it is recommended for:
On the other hand, DeepSeek is not well suited for people who want to write creative texts (novels or poetry), look up the latest news, or businesses that need to handle confidential information.
For those use cases, ChatGPT, Claude, or Perplexity would be more appropriate.
This is because DeepSeek is a tool specialized in "thinking logically to arrive at an answer."
DeepSeek is a free AI tool from China, notable for its particular strengths in mathematics and programming. Here is a summary of the key points in this article, including the latest information as of April 2026.
DeepSeek is an extremely powerful tool, especially for students, programmers, and anyone who needs logical problem-solving.
Since it's free to use, why not visit the official website (chat.deepseek.com) and try it out for yourself — for example, by entering a math problem or asking it to generate some code?
You may well be surprised by how capable the AI is.
That said, please be careful not to enter any confidential information.
This article is a cross-post from AI Friends.
