DeepSeek Chat - the free AI assistant that took the #1 App Store spot in 157 countries. Two modes: Instant for quick answers, Expert for frontier reasoning. DeepThink lets you watch the AI work through hard problems step by step.
Expert Mode activates full chain-of-thought reasoning. Watch the AI work through a complex problem before giving its answer — complete transparency into how it thinks.
def sieve(n):
is_prime = [True] * (n + 1)
is_prime[0] = is_prime[1] = False
for i in range(2, int(n**0.5) + 1):
if is_prime[i]:
for j in range(i*i, n+1, i):
is_prime[j] = False
return [i for i, v in enumerate(is_prime) if v]
primes = sieve(1000)
print(f"Found {len(primes)} primes up to 1000")
print(primes[:10]) # First 10: [2, 3, 5, 7, 11, 13, 17, 19, 23, 29]
DeepSeek Chat added Instant and Expert modes in April 2026 alongside the V4 launch - giving users explicit control over speed vs. depth for every conversation.
The default mode for everyday use. Powered by V4-Flash - 284B parameters with 13B active per token. Responses stream in under a second for most queries. No visible reasoning chain; just clean, direct answers.
The flagship reasoning mode. Activates V4-Pro - 1.6T parameters, 49B active — with Think Max reasoning enabled. The AI works through the problem internally before responding. May show its reasoning chain via DeepThink. Worth waiting for on hard problems.
Two independent toggles sit above the input field in both Instant and Expert modes. Mix and match with any mode to customize every message.
Enables visible chain-of-thought reasoning. When active, the AI shows its internal thinking process before giving the final answer — a transparent reasoning trace you can read, learn from, and audit. In Expert Mode, this is particularly powerful: watch the model work through proofs, debug logic, and try multiple approaches.
Think Max · Chain-of-thought · AuditableConnects the AI to live web results for real-time information. When enabled, DeepSeek searches the web before responding — ideal for current events, news, prices, recent research, and anything where its training data might be outdated. Returns cited, grounded results with source references.
Real-time · Cited results · Current eventsUpload documents directly into the conversation. Supports PDF, DOCX, TXT, and code files. The AI extracts text and reasons over the full content — summarize research papers, extract key points from contracts, ask questions about uploaded code, or analyze entire reports. 1M token context means even large files fit.
PDF · DOCX · TXT · Code · 1M contextFull chat history is saved automatically and synced across all devices. Access past conversations any time — rename, search, or delete individual chats from the sidebar. Multi-turn context is maintained within each session, so the AI always knows the full conversation history.
Auto-save · Cross-device sync · SearchableDeepSeek Chat is a complete AI assistant — not just a model wrapper. Every detail of the interface and capability set is thoughtfully designed for daily use.
No daily message cap. No throttle after 40 messages. No premium tier needed. Talk as much as you want, with as much context as you need — completely free.
No limitsClean, responsive web app at chat.deepseek.com. Sidebar for conversation history, inline code rendering, markdown support, copy buttons on all responses, and regenerate option.
chat.deepseek.comNative apps with full feature parity — DeepThink, web search, file upload, and cross-platform sync. Available free on the App Store and Google Play. #1 in 157 countries on App Store.
iOS · AndroidSyntax-highlighted code blocks for 100+ languages. Copy button on every snippet. Multi-file code responses with file labels. Inline code in markdown. The best free coding AI experience.
100+ languagesLaTeX math rendering inline and block. Equations display beautifully in both Instant and Expert mode. Essential for working through proofs, deriving formulas, or reviewing technical documents.
LaTeX renderedResponds naturally in 50+ languages. Particularly strong in Chinese and English. Switch languages mid-conversation. Outperforms most models on Chinese-language tasks and technical content.
50+ languagesPaste entire codebases, research papers, legal contracts, or book-length documents. 1M tokens = ~750,000 words. The full context of every long conversation is maintained without truncation.
~750K wordsDislike a response? Hit regenerate to get a fresh answer from the same prompt. Like/dislike buttons on all responses — feedback is used to improve the model over time.
IterativeEdit any message in the conversation and regenerate from that point. Branch different approaches to the same prompt. Copy-paste your prompt drafts before sending with Shift+Enter for multi-line input.
Full edit historyGenerate shareable links for individual conversations. Share a research session, a debugging thread, or a math proof walkthrough — the shared link renders the full conversation with formatting.
Shareable linksRegister with Gmail, Google Account, or Apple ID. Email verification only — no phone number required (in most regions). Minimal onboarding. Chat within 60 seconds of landing.
Email/Google/AppleDeepSeek Chat has no advertising, no promoted results, and no sponsored content. DeepSeek's model is research-first — the chat is a product demo and API onramp, not a monetized ad platform.
Zero adsFrom students tackling homework to researchers analyzing papers — DeepSeek Chat covers every intelligent task at zero cost.
Write, review, and debug code in any language. Expert Mode with DeepThink traces through logic errors step by step. Codeforces #1 (3206 Elo) — better at competitive algorithms than any other free AI.
97.3% MATH-500 in Expert Mode. Show full working for proofs, derivations, and competition problems. Ideal for students, researchers, and engineers who need rigorous step-by-step solutions.
Upload a PDF — research paper, legal contract, financial report — and ask questions about it. The 1M token context means even book-length documents are processed in full, without chunking or summarization artifacts.
Drafts, edits, and polishes emails, essays, blog posts, reports, and creative writing. Instant Mode gives quick suggestions; Expert Mode analyzes structure and argument quality. Particularly strong at technical writing.
Toggle Web Search to get cited, current results. Ask follow-up questions like a tutorial. Expert Mode builds deep understanding by showing reasoning at every step — the best free AI tutor for complex subjects.
Practice conversations in Chinese, Japanese, Spanish, French, and 45+ other languages. Ask for corrections, grammar explanations, and vocabulary. DeepSeek is particularly praised by Chinese learners for its native-quality Chinese.
Paste CSV data, SQL queries, or statistical output and ask for analysis, interpretation, or visualizations described in code. Expert Mode reasons through statistical methodology with academic rigor.
Brainstorm product ideas, business models, story plots, marketing angles, or research directions. Instant Mode delivers fast, varied suggestions. Expert Mode thinks through feasibility and trade-offs.
Multi-step analysis for legal, medical, financial, and business decisions. Expert Mode reasons through arguments like a specialist — identifying assumptions, gaps, and counter-arguments before concluding.
The same free, unlimited AI on every platform — browser, phone, or tablet. Cross-platform history sync means your conversations follow you everywhere.
Full-featured browser experience at chat.deepseek.com. No download needed. Works on any device with a modern browser. Best experience on desktop.
Open chat.deepseek.com →#1 US App Store, January 2026. Native iPhone and iPad app with full feature parity — DeepThink, Search, and file upload. Apple ID login supported.
Download on App Store →Official app on Google Play. Same capabilities as web and iOS. Google Account login. Cross-platform history syncs instantly between all your devices.
Get it on Google Play →No payment info, no waiting lists, no onboarding tour. Just sign up and start asking.
Visit chat.deepseek.com or download the iOS/Android app. Click Sign Up and register with your Gmail, Google Account, or any email. Email verification takes about 30 seconds.
The default is Instant Mode (V4-Flash, fast). For hard problems — math, complex code, research analysis — click Expert Mode in the top bar to switch to V4-Pro with Think Max.
The DeepThink button above the input field shows the AI's chain-of-thought before the answer. Turn it on when you want to see the reasoning, or when you need maximum accuracy on hard questions.
The Search toggle enables real-time web search. Turn it on when your question is about recent events, current prices, news, or any topic where your training data might be stale.
Click the paperclip icon to upload a PDF, DOCX, TXT, or code file. After uploading, ask questions about the content — the AI has read the full document and can cite specific sections.
Click any message to edit it and regenerate from that point. Click the share icon on any conversation to get a shareable link. Access your full conversation history from the left sidebar.
How the free DeepSeek Chat compares to other major AI assistants in 2026 — features, cost, and capability.
| Chatbot | Free tier | Message limit | Reasoning mode | Web search | File upload | Context |
|---|---|---|---|---|---|---|
| DeepSeek Chat | ✓ Full access | Unlimited | ✓ Expert Mode | ✓ Included | ✓ Included | 1M tokens |
| ChatGPT (Free) | Partial | ~40/day (GPT-4o) | ✗ Paid only | Limited | Limited | 128K |
| Claude (Free) | Partial | ~25/day (Sonnet) | ✗ Paid only | ✗ Paid only | Limited | 200K |
| Gemini (Free) | Partial | Throttled | ✗ Paid only | ✓ Included | Limited | 1M |
Data as of May 2026. "Limited" = feature available but with restrictions. DeepSeek Chat: fully free, no declared usage limits.
DeepSeek is powerful and free — but it's also a Chinese company with data practices and regulatory scrutiny worth understanding before you use it for sensitive work.
Data residency: Conversations are stored on servers in China. DeepSeek's privacy policy states your data may be subject to Chinese law, including government access requests. This is a meaningful consideration for sensitive personal, business, or government-related conversations.
Regulatory scrutiny: DeepSeek has faced bans or restrictions in Italy, South Korea, and has attracted scrutiny in Germany, the US, and Australia over data practices and censorship policies. Check your jurisdiction's regulations before using it for work data.
For sensitive use cases: Enterprise users handling confidential data should consider routing through AWS Bedrock or Azure AI — which host DeepSeek models with GDPR-compliant EU data residency and enterprise SLAs — rather than the direct chat interface.
Open-source models: The model weights are MIT-licensed and publicly auditable on Hugging Face. The inference infrastructure and training data are not open. For maximum privacy, self-host the distilled models locally.
Yes. Access to chat.deepseek.com is completely free with no declared usage limits. This includes both Instant Mode (V4-Flash) and Expert Mode (V4-Pro), DeepThink reasoning, web search, and file upload. There is no premium subscription plan for the consumer chat — DeepSeek's business model is the API (usage-based, starting at $0.14/1M tokens), not the chat interface. The chat is primarily a demonstration of DeepSeek's models for the research community and public. The app announcement explicitly states: "100% free, no ads, no in-app purchases."
Instant Mode uses DeepSeek-V4-Flash — a 284B MoE model with 13B active parameters delivering fast (~83 tok/s) responses. Best for everyday questions, writing, simple coding, and anything where speed is the priority. Expert Mode uses DeepSeek-V4-Pro — the 1.6T flagship with 49B active parameters and Think Max reasoning. Responses take longer but achieve frontier-level quality: 80.6% SWE-bench, 97.3% MATH-500, Codeforces #1 at 3206 Elo. Start with Instant Mode for most tasks; switch to Expert Mode when you need the absolute best answer on hard problems.
DeepThink enables visible chain-of-thought reasoning — the AI generates an internal reasoning trace and shows it to you before the final answer. This is powered by Think Max mode (high reasoning effort). When DeepThink is on, you'll see a collapsible "thinking" section above the response containing the AI's step-by-step reasoning process. This is distinct from the final answer. DeepThink is particularly useful for math proofs, complex debugging, strategic analysis, and any task where you want to verify the AI's logic — not just accept the conclusion. Enable it by clicking the DeepThink toggle above the input field.
DeepSeek's free tier is significantly more generous. ChatGPT Free caps GPT-4o access at ~40 messages/day and restricts reasoning models, advanced file analysis, and longer context to paid Plus subscribers ($20/month). DeepSeek Chat offers unlimited messages with V4-Flash, unlimited Expert Mode (V4-Pro + Think Max), web search, and file upload — all free. On benchmarks: V4-Pro competes with or beats GPT-5.5 on math and coding while remaining free to use in chat. The main advantages ChatGPT retains: more polished creative writing and narrative, more mature enterprise features, and better geopolitical data privacy for users in regulated industries.
Click the paperclip icon in the bottom-left of the input field to open the file upload dialog. Supported formats: PDF, DOCX, TXT, and most code file extensions. You can also drag-and-drop files directly into the chat window. After upload, the AI extracts all text from the document and makes it available as context. Ask any question about the content: "Summarize this paper", "List the key findings", "Find any contradictions", "What are the risks mentioned in this contract?" The 1M token context window means even large documents (entire books or codebases) can be processed in full.
DeepSeek-R1 launched January 20, 2025, and by January 27 it had surpassed ChatGPT as the #1 free app on the US iOS App Store. Several factors converged: (1) R1 matched OpenAI o1's performance at 90–95% lower cost, shocking the AI industry. (2) The launch triggered an 18% drop in Nvidia's stock — the largest single-day market cap loss in US history at the time — generating enormous press coverage. (3) The model was truly free with no usage limits, unlike ChatGPT. (4) The open-source MIT license made it verifiable by the research community. (5) It demonstrated that China had closed the perceived AI capability gap, generating intense public interest. The "Sputnik moment" narrative spread widely, turning a model launch into a global news story.
This depends on what data you're sharing. For general questions, learning, and public information: fine. For sensitive work data, confidential business information, or personal medical/financial details: exercise caution. DeepSeek is a Chinese company; conversations are stored on servers subject to Chinese law and potentially accessible to Chinese authorities. Italy, South Korea, and others have restricted or banned DeepSeek for government and regulatory reasons. If you handle sensitive data professionally, consider: (1) Self-hosting distilled R1 models locally via Ollama — no data leaves your machine. (2) Routing through AWS Bedrock or Azure AI which offer GDPR-compliant EU hosting for DeepSeek models with enterprise SLAs. (3) Simply using DeepSeek for non-sensitive queries and a more privacy-conscious provider for confidential work.
No subscription. No message limits. No ads. Expert Mode with V4-Pro reasoning, DeepThink, web search, and file upload — all free, forever. Start in 60 seconds.