DeepSeek V4 Pro MIT Open Source
DeepSeek Web app · V4 Pro · Free chat
Free DeepSeek web chat, plus an OpenAI-compatible API for AI chat, coding assistance, long-document processing, and API integration
What is DeepSeek?
DeepSeek is an open-source large language model for chat, coding and long documents. This site offers a free DeepSeek web app for V4 Pro, plus an OpenAI-compatible DeepSeek API for developers.
1. Why choose DeepSeek?
Open Source & Free
MIT license — free for commercial use and customization
Peak Performance
Codeforces 3206 — surpassing closed-source models
Global Community
500K+ developers across 24 languages
Rich Ecosystem
API, SDK, tutorials — ready out of the box
2. Core Capabilities
1M Token Context 1M
Process long documents, codebases, and complex tasks with ease.
📌 Measured: 100-page PDF analysis in just 12 seconds
Top‑Tier Reasoning 3206
Codeforces 3206, outperforming all open‑source models in STEM.
📌 Codeforces rating — surpassing all open-source models
Vision‑Primitive Mode Vision
Precise spatial reasoning with minimal token consumption.
📌 Chart & UI screenshot analysis with minimal tokens
DSpark Acceleration 85%
Speculative decoding boosts response speed by up to 85%.
📌 Speculative decoding: 45 tok/s → 83 tok/s on code generation
3. Use Cases
Explore how DeepSeek powers diverse workflows
Development
- Smart completion, code review, bug fixing
- Data cleaning, trend analysis, visualization tips
Knowledge & Research
- Paper analysis, literature review, experiment design
- Personalized learning, homework help, Q&A
Creative & Service
- Storytelling, copywriting, content polishing
- 24/7 automated customer assistance
4. Benchmarks
Comparison with Closed‑Source Models
5. What Developers Say
"DeepSeek V4's coding ability amazed me — it solved a 3-day algorithm problem with crystal-clear explanations."
"As a researcher, the 1M context lets me feed entire papers for analysis — 10× productivity boost."
"DSpark cut our API latency from 2s to 300ms — a game-changer for user experience."
6. Model Comparison
Side-by-side comparison of leading AI models
| Dimension | DeepSeek V4 Pro | DeepSeek V4 Flash | GPT-4o |
|---|---|---|---|
| Context Window | 1M | 128K | 128K |
| Codeforces | 3206 | 2800+ | 2800+ |
| Price / 1M Input | $0.14 | $0.07 | $5.00 |
| Open Source | ✅ | ✅ | ❌ |
| Vision Mode | ✅ | ❌ | ✅ |
7. Frequently Asked Questions
What is DeepSeek V4 Pro GA, and how do I start?
DeepSeek V4 Pro GA is the flagship model: about 1M context, vision understanding and stronger reasoning. Start a free web chat here, or call the OpenAI-compatible DeepSeek API. This site is an independent community with tutorials and guides — not the official DeepSeek company site.
Where is the DeepSeek web app? Do I need to download it?
No download needed. Use Start Chat on this site for the DeepSeek web experience. For official API keys, register at platform.deepseek.com. Try the web app first, then integrate when you are ready.
What's the difference between V4 Pro and V4 Flash?
V4 Pro is for long documents, deep reasoning and vision, with about 1M context. V4 Flash is faster and cheaper for everyday Q&A and high traffic. Unsure? Run one real task in the web app, then pick by latency and cost.
How do I use DeepSeek's free API?
Sign up at platform.deepseek.com for an API key. The API is OpenAI-compatible — set base_url to https://api.deepseek.com/v1. New accounts usually include a free quota; usage beyond that is billed per token.
How is DeepSeek different from ChatGPT?
DeepSeek is open-source with a free trial path, a longer V4 Pro context window, strong coding scores (Codeforces 3206) and usually much lower API prices than GPT-4o. ChatGPT has a more mature product ecosystem. Use our benchmarks and tutorials to choose by task.
Can I run DeepSeek locally, and which languages does it support?
Yes. Deploy with Ollama, vLLM or SGLang — see Tutorials. DeepSeek works well in Chinese and English and covers 50+ programming languages. Individuals can start in the web app; teams can move to API or local deploy.
8. Start here on this site
9. 📰 Latest News
DeepSeek Harness v0.2.1-alpha.2: Worktrees & Channel Trap
DeepSeek Harness v0.2.1-alpha.2 is prerelease: Git Worktrees, working_directory, reasoning translate; npm latest stays 0.2.0-rc.2, both mode gone.
Oct 13, 2026DeepSeek OpenCode Setup: /connect, Version Gate, Flash
DeepSeek OpenCode setup: upgrade to ≥v1.18.30, /connect → deepseek → API key → DeepSeek-V4-Flash; vs Codex, Copilot, Harness.
Oct 13, 2026DeepSeek GitHub Copilot Setup: Chat Extension and CLI
DeepSeek GitHub Copilot setup: install the Chat extension into the model picker, or wire Copilot CLI with Anthropic BYOK—and avoid the reasoning_content 400.
Oct 8, 2026