In early 2025, DeepSeek suddenly appeared on everyone’s radar, briefly topping the global App Store download charts and sending Nvidia’s US stock price down by nearly 17%. If you didn’t understand what it was back then, you likely never used it seriously—once the hype died down, many people put it aside. But as an AI tool, DeepSeek is worth understanding not for its fleeting popularity, but for its actual capabilities.
This article aims to clarify: what DeepSeek can actually do, how it differs from ChatGPT and other AIs, and when it’s best suited for use.
What Is DeepSeek?
DeepSeek is a large language model product developed by DeepSeek (DeepSeek), a company headquartered in Hangzhou and backed by the quantitative private equity firm High-Flyer Technologies (High-Flyer Technologies). DeepSeek stands out as somewhat of an outlier in the AI field—the team is relatively small, yet the model quality is exceptionally high. They have adopted an open-source strategy, publicly releasing model weights so that developers worldwide can download and use them.
There are currently two main product lines:
DeepSeek-V4-Pro: The flagship general model — a 1.6-trillion-parameter MoE with roughly 49B active, a native 1M-token context window and up to 384K output. The 0813 build that went GA on August 12, 2026 focuses on agentic coding, and does not accept image input.
DeepSeek-V4-Flash: The lighter tier — 284B parameters with roughly 13B active, also with a 1M-token context window, generally available since July 31, 2026. A multimodal variant, V4-Flash-Vision-Exp, arrived on August 21, billing images as tokens based on their size.
You can access it directly via chat.deepseek.com without complex registration or a credit card—it is completely free, a rarity among AI tools.
The Reason for Its Fame: Cost Efficiency
What shook the entire AI industry was not just DeepSeek’s capabilities, but its cost structure.
According to data released by DeepSeek, training the V3 model required only about $5.57 million in GPU compute power. Compared to the hundreds of millions of dollars spent by OpenAI and Anthropic, this figure isUnbelievable (unbelievably) low. While the authenticity of this number has been debated, the industry widely acknowledges that DeepSeek’s training efficiency far exceeds its peers.
The significance of this is that it proves high-performance models do not require insane compute spending, directly challenging the industry narrative that "more Nvidia GPUs are always better."
For ordinary users, this means the web app and mobile app give you this generation's frontier models at no cost.
Core Capabilities
Mathematics and Reasoning
This has long been DeepSeek's standout feature.
Math and reasoning have long been DeepSeek strengths — solving equations, proving theorems and working through probability and statistics with clear logic — and the V4 series holds that line. For specific scores, check current official and third-party benchmark runs.
Its reasoning style can be described as "think slowly, think clearly, then speak." With deep thinking enabled it shows a "thinking process" before answering, laying out the reasoning chain step by step so you can see how it reaches a conclusion. That transparency lets you check its logic, and it also means longer response times.
Coding
Code generation is where the V4 series improved most visibly, with large published gains on agentic coding and terminal task benchmarks.
It covers common languages well: Python, JavaScript, TypeScript, Java, Go, C++. It can help you write functions, debug errors, refactor code, explain logic, and add comments. For backend developers handling algorithmic problems and logic-intensive tasks, deep thinking mode is particularly useful because it analyzes step by step rather than jumping straight to a conclusion.
Chinese Understanding and Generation
As a model developed by a domestic team, DeepSeek’s Chinese understanding and generation are naturally robust. It accurately understands ambiguous Chinese expressions, and its generated Chinese is fluent and natural, unlike some models that suffer from heavy "translationese."
It handles Chinese documents, writing assistance, and administrative official documents well, without spitting out excessive filler content.
Long-Text Processing
The V4 series ships a native 1M-token context window, so feeding in a full contract, a long report or several code files and then asking questions is routine — context is no longer the pinch point it used to be.
Comparison with Other AI Tools
vs ChatGPT:
In terms of pricing, DeepSeek is completely free, while ChatGPT has usage limits and requires payment for full features.
On capability, the V4 series competes directly with comparable overseas models on mathematics, coding and logical reasoning. ChatGPT's ecosystem (GPTs, plugins, image generation, voice, browsing) is still more complete, and its multimodal support more mature.
In terms of Chinese experience, DeepSeek’s Chinese is more idiomatic, whereas ChatGPT can sometimes feel overly translated.
vs Claude:
In reasoning tasks the two trade wins; both sit in the top tier. In writing style, Claude's language is more natural and fluid, while DeepSeek reads slightly more "formal" but still holds up. On context length the V4 series has caught up — both are now in the million-token range.
vs Domestic Products (Kimi, ERNIE Bot, Tongyi Qianwen, etc.):
DeepSeek’s mathematics and coding capabilities are significantly ahead among domestic models. ERNIE Bot and Tongyi Qianwen have stricter content safety reviews; DeepSeek is slightly more open on some topics (though it still has content restrictions and is not without censorship). Kimi has specialized optimizations for long-text processing, making it competitive in the specific scenario of document handling.
Who Should Use DeepSeek?
Students and Researchers: For maths problems, derivations and physics or chemistry questions, the chain-of-thought in deep thinking mode helps a lot — you get the process, not just the answer.
Developers: For coding issues, algorithmic problems, and debugging, it is free, powerful, and offers extremely high cost-performance value.
Users Who Need High-Frequency AI Access Without Paying: The free version has almost no functional limits (with some queuing during peak hours), making it one of the strongest alternatives to ChatGPT’s free tier.
Chinese Writing Scenarios: For official documents, reports, and copywriting, DeepSeek’s Chinese output quality is good, and you don’t have to worry about usage quotas.
Practical Usage Tips
Turn on deep thinking for hard reasoning. Ordinary chat mode is the default. For maths, logical reasoning and complex coding problems it is clearly steadier, if slower, and the "thinking process" is often the valuable part.
Look at its thinking process, not just the conclusion. The thinking section lays out the full reasoning chain, so when a conclusion looks wrong you can usually find the flawed assumption inside it.
Use ordinary mode for daily conversation and writing. It is fast and sufficient for most scenarios; there is no need to enable deep thinking every time.
Don’t ask for real-time information. DeepSeek does not have web-browsing capabilities (by default); it doesn’t know what happened today, so don’t use it as a search engine.
Describe complex tasks directly in Chinese. No need to force yourself to use English—its Chinese understanding has no obvious weaknesses. Clear descriptions in Chinese usually yield excellent results.
Important Notes
Content Restrictions Apply. DeepSeek still has content filtering mechanisms; it will refuse to answer or provide official stances on politically sensitive topics.
Queuing During Peak Hours. Being free and popular, you may occasionally encounter wait times during daytime working hours. If you’re in a hurry, use it during off-peak hours or access it via the API.
Data Privacy. As with all online AI services, do not input company secrets or personal sensitive information.
API and Developer Usage
DeepSeek offers API access at extremely low prices—roughly one-tenth or even less of GPT-4o’s cost—while delivering comparable model quality. Many developers and startup teams have already adopted the DeepSeek API as a cost-effective alternative to OpenAI’s API, achieving significant savings.
Additionally, DeepSeek has open-sourced its model weights, which are available for download on Hugging Face. Teams with the infrastructure to deploy models locally can operate entirely independently of cloud services, maintaining full control over their data—a valuable advantage for enterprise users navigating compliance requirements.
Summary
DeepSeek is a genuinely outstanding AI tool, not driven by hype but by tangible capability. Its combination of free access, strong Chinese language support, and robust math and coding performance has no direct equivalent in the current market.
If you haven't given it a serious try, visit chat.deepseek.com and put it on a real reasoning task — a moderately hard maths problem, or code logic analysed with deep thinking on so you can watch the "thinking process." It usually performs better than expected.