What is DeepSeek?
DeepSeek is a Chinese AI lab and a family of language models that have become the most relevant open source player of 2026. Its reasoning model DeepSeek-R1 reached parity with OpenAI’s o1/o3 at a fraction of the training cost, and its release moved the stock market and forced big tech to rethink pricing.
Founded in 2023 by High-Flyer (a Chinese quantitative fund), DeepSeek bets on publishing open weights, papers, and models. Anyone can download the models, run them on their own servers, or call them via API at a cost far below OpenAI or Anthropic.
Who is DeepSeek for?
- Developers who need a powerful API at the lowest per-token cost on the market.
- Companies with sensitive data who want to run the model on their own infrastructure.
- Researchers and academics who can study the full model, its weights, and architecture.
- Curious users looking for a free alternative to ChatGPT Plus for reasoning and code tasks.
- Technical teams who want to customize the model via fine-tuning.
Core features
1. R1 reasoning model
DeepSeek-R1 thinks step by step before answering. On math, logic, and programming problems it plays in the o1/o3 league. You can see the full chain of reasoning, which helps verify the result and learn from the model.
2. V3 generalist model
DeepSeek-V3 is the standard conversational model, equivalent to GPT-4o. Fast, capable for chat, writing, and code, with a wide context window and good performance in English.
3. Real open weights
Weights are published under a permissive license on Hugging Face. Anyone can download them, run locally (with sufficient hardware), fine-tune, or build derivative services without asking permission.
4. Ultra-cheap API
The per-token price of the DeepSeek API is between 10 and 30 times lower than OpenAI’s for models of comparable capability. For high-volume projects, the cost difference is radical.
5. Free web and app
At chat.deepseek.com you have free access to the reasoning model, with no credit cards or strict limits. The mobile app offers the same experience.
Real-world use cases
Programming and technical problem solving
R1 excels at competitive programming, complex debugging, and refactoring. A developer can paste a hard bug and watch the model reason about the root cause before proposing a fix.
Math and science analysis
R1 solves olympiad-level math problems with detail. University students, researchers, and exam candidates use it as a tutor that explains the path, not just the result.
High-volume APIs
Services processing millions of tokens daily (summaries, classification, assistants) use DeepSeek to slash their bill without sacrificing quality on medium-complexity tasks.
Pricing and plans
| Mode | Price | Features |
|---|---|---|
| Web/App | Free | Access to R1 with generous limits · no card required |
| V3 API | ~$0.14/M input · $0.28/M output | Between 10 and 30 times cheaper than GPT-4o |
| R1 API | ~$0.55/M input · $2.19/M output | Comparable to o1 at a fraction of the cost |
| Self-hosted | Hardware cost only | Weights downloadable on Hugging Face |
DeepSeek vs. ChatGPT and Claude
| Criterion | DeepSeek | ChatGPT (GPT-4o) | Claude |
|---|---|---|---|
| Math reasoning | Excellent (R1) | Excellent (o1/o3) | Excellent |
| Conversation in English | Good | Excellent | Excellent |
| Code | Excellent | Excellent | Best on the market |
| API price | Very low | High | High |
| Open source | Yes | No | No |
Pros and cons
✓ Strengths
- Quality comparable to the best closed models
- Weights published openly and downloadable
- API 10 to 30 times cheaper than OpenAI
- R1 model with visible reasoning chain
- Free web and app, no card required
- Fine-tuning and self-hosting possible
✗ Weaknesses
- Servers in China: be cautious with sensitive data
- Censorship of certain political topics in the web version
- Conversational quality slightly below ChatGPT in some languages
- No integrated web search in the public plan
- Smaller extension ecosystem than OpenAI
- Less predictable policy and availability changes
Frequently asked questions about DeepSeek
Is it safe to use DeepSeek with my data?
The web version sends your data to servers in China, which for many European companies is incompatible with GDPR. For sensitive cases, the recommended path is to run the model on your own server (weights available on Hugging Face) or use the API through European intermediaries with local jurisdiction.
How does DeepSeek-R1 differ from DeepSeek-V3?
V3 is a fast, cheap generalist model, equivalent to GPT-4o. R1 specializes in reasoning: it thinks step by step and performs much better on complex math, logic, and programming. Use V3 for fast tasks and R1 when you need depth.
Why is DeepSeek so cheap?
Three reasons: efficient architecture (well-implemented Mixture of Experts), training optimized for more accessible hardware, and an explicit strategy of competing on price to gain share against OpenAI and Anthropic. The model is genuinely cheaper to train and serve.
Can I use DeepSeek for my business with confidence?
For general commercial use, yes. For sensitive or regulated data (healthcare, finance, EU personal data), it’s worth self-hosting the model or using a European provider. Technical quality is not in question; the consideration is data sovereignty.
Related reads on NodoAI
- State of LLMs in 2026 · the global comparison including DeepSeek.
- ChatGPT · the other market leader.
- Claude · the writing and code champion.
- Open-source models 2026 · ecosystem context.
- DeepSeek 2026 guide
- DeepSeek vs ChatGPT
