DeepSeek AI Facts: V2 to V4, API Models, Privacy, and What Users Need to Know Now

DeepSeek is no longer just a story about one Chinese chatbot or one open reasoning model. It is now a fast-moving model family and platform with official web, app, API, and open-weight releases. This guide rebuilds the DeepSeek AI timeline from primary sources and explains what is current as of April 26, 2026.

Last verified against official DeepSeek sources: April 26, 2026.

Disclosure: Chat-Deep.ai is an independent DeepSeek resource hub. It is not the official DeepSeek website, app, API platform, billing system, or support channel.

Current V4 update: DeepSeek-V4 Preview is now officially live and open-sourced. DeepSeek’s current API model IDs are deepseek-v4-flash and deepseek-v4-pro. The older names deepseek-chat and deepseek-reasoner are now legacy compatibility names that route to deepseek-v4-flash non-thinking and thinking modes during the transition, and DeepSeek says they will be fully retired after July 24, 2026, 15:59 UTC.

Quick take

• V4 is the current official DeepSeek release line. DeepSeek-V4 Preview went live on April 24, 2026, with V4-Pro and V4-Flash available through DeepSeek Chat and the API.
• The current API model IDs are deepseek-v4-flash and deepseek-v4-pro. Use these names in new integrations instead of deepseek-chat or deepseek-reasoner.
• V4 API models support a 1M context length and up to 384K maximum output. This replaces the older V3.2-era 128K / 64K wording used in many outdated guides.
• deepseek-chat and deepseek-reasoner are legacy names now. They currently correspond to V4-Flash non-thinking and thinking modes for compatibility, but they are scheduled for retirement after July 24, 2026.
• DeepSeek-V3.2 remains important, but it is no longer the newest official general release. Treat V3.2 as the previous V3-line milestone and a historical transition point toward V4.
• Licensing varies by release. Newer releases such as R1, V3.1, V3.2, and V4 are presented through official open-weight channels, but older families and specialized lines may use different license terms. Always check the exact model card or repository.
• Privacy is a first-order issue. DeepSeek’s own privacy policy says prompts, uploaded files, chat history, device/network data, and other data may be collected, used to improve services, and processed/stored in the People’s Republic of China. Do not enter sensitive personal or regulated data unless you have a clear legal and technical basis to do so.

What changed since older DeepSeek explainers?

Older DeepSeek articles often stop at DeepSeek-V3, DeepSeek-R1, or DeepSeek-V3.2. That is now incomplete. As of April 26, 2026, the official DeepSeek release stream includes DeepSeek-V4 Preview, and the official API documentation has moved to deepseek-v4-flash and deepseek-v4-pro.

This matters because the old API names were not permanent model identities. During 2025, deepseek-chat and deepseek-reasoner moved through several underlying releases. In December 2025, they mapped to V3.2 non-thinking and thinking modes. On April 24, 2026, DeepSeek changed the current API surface again: the new model IDs are V4-specific, while the old names are now compatibility aliases for V4-Flash.

Current official API situation

DeepSeek’s API remains OpenAI-compatible and Anthropic-compatible. For OpenAI-style chat completions, the base URL remains https://api.deepseek.com. For Anthropic-style integrations, DeepSeek documents https://api.deepseek.com/anthropic. The key change is the model value: new code should use deepseek-v4-flash or deepseek-v4-pro.

Official pricing source: DeepSeek API prices can change, so this facts page does not publish fixed token-price numbers. For the latest official API rates, cache-hit/cache-miss billing details, and any temporary promotions, use the official DeepSeek Models & Pricing page.

Practical rule: Use deepseek-v4-flash when speed and efficiency matter most. Use deepseek-v4-pro when the task needs stronger reasoning, coding, agentic behavior, or long-context performance. Keep deepseek-chat and deepseek-reasoner only in migration notes or legacy code references.

API names vs. model family names

A lot of DeepSeek confusion comes from mixing up API model IDs, legacy aliases, and model-family release names.

• Current API model IDs: deepseek-v4-flash and deepseek-v4-pro. These are the names developers should send in new API calls.
• Legacy API names: deepseek-chat and deepseek-reasoner. These are transition aliases for V4-Flash and are scheduled to be retired.
• Model-family names: DeepSeek-V2, DeepSeek-V2.5, DeepSeek-V3, DeepSeek-R1, DeepSeek-V3.1, DeepSeek-V3.2, and DeepSeek-V4. These are release names used in technical reports, repositories, and model cards.

In short: use the current API model ID when writing code, and use the family name when explaining the model history.

The DeepSeek model timeline, rebuilt from primary sources

DeepSeek-V2 and V2.5: the efficiency and consolidation era

DeepSeek-V2 is the first milestone in the modern DeepSeek timeline that still matters for today’s model story. The official model card describes DeepSeek-V2 as a Mixture-of-Experts model with 236B total parameters, 21B activated parameters per token, and efficient inference techniques. V2 helped establish DeepSeek’s emphasis on cost-effective training and inference.

DeepSeek-V2.5 then consolidated two paths: general chat and coding. The official September 2024 release note says V2.5 combined DeepSeek-V2-0628 with DeepSeek-Coder-V2-0724, keeping general conversation ability while retaining stronger code processing. This matters because DeepSeek’s later releases increasingly blended general reasoning, coding, tool use, and long-context workflows instead of keeping them as separate product stories.

DeepSeek-V3 and R1: scale first, reasoning second

DeepSeek-V3 expanded the main general model line. DeepSeek’s official V3 announcement lists 671B MoE parameters, 37B activated parameters, and training on 14.8T high-quality tokens. For users, the important practical point was that the API surface stayed compatible while the model behind it improved.

DeepSeek-R1 then pushed the reasoning story forward. DeepSeek’s R1 release note presented R1 as a reasoning-focused model and said the code and models were released under the MIT License. At the time, API users could access R1 by setting model=deepseek-reasoner. That was historically accurate in January 2025, but it is not the right way to describe the current API in April 2026, because deepseek-reasoner is now a legacy compatibility alias for V4-Flash thinking mode.

DeepSeek-V3.1, V3.2, and the road to V4

DeepSeek-V3.1 was the first explicit bridge toward the current model design. DeepSeek called it its “first step toward the agent era,” with one model supporting both thinking and non-thinking modes, stronger tool use, and support for Anthropic API format. That design idea now carries forward into V4, where both V4-Flash and V4-Pro support thinking and non-thinking modes.

DeepSeek-V3.2-Exp introduced DeepSeek Sparse Attention (DSA) as an efficiency mechanism for long context. DeepSeek-V3.2 followed as the official successor to V3.2-Exp and was described by DeepSeek as a reasoning-first model built for agents. In older content, it was fair to call V3.2 the latest official general API release. After April 24, 2026, that wording is outdated: V4 is now the current release line.

DeepSeek-V4 today: Flash vs Pro

DeepSeek-V4 Preview is the current official release line. DeepSeek describes DeepSeek-V4-Pro as a 1.6T total / 49B active-parameter model and DeepSeek-V4-Flash as a 284B total / 13B active-parameter model. In the official release note, DeepSeek positions V4-Pro for stronger reasoning, coding, agentic, and world-knowledge performance, while V4-Flash is presented as the faster and more efficient choice.

For developers, the most important V4 facts are simple:

• Use deepseek-v4-flash or deepseek-v4-pro in the model field.
• The base URL does not need to change. DeepSeek says to keep the same base URL and update the model name.
• Both current V4 API models support 1M context and dual thinking / non-thinking modes.
• Both current V4 API models support JSON Output, Tool Calls, Chat Prefix Completion, and FIM Completion in non-thinking mode.
• Legacy names are temporary.

Official access methods today

DeepSeek’s official access paths include the web product, app, API, and open-weight releases. DeepSeek’s app announcement lists App Store, Google Play, and major Android market availability, with features such as email/Google/Apple login, cross-platform chat history sync, web search, Deep-Think mode, file upload, and text extraction. The V4 release note also says V4 can be tried through DeepSeek Chat via Expert Mode and Instant Mode.

The access caveat is important: the hosted API, the web/app experience, and downloadable open weights are not always identical. DeepSeek itself has previously noted that the API model mapping can differ from the App/Web version. For production decisions, verify the exact official page for the access path you plan to use.

Open weights, code, and licensing

The safest licensing rule is: do not assume every DeepSeek model has the same license. Check the exact official repository, model card, or release note for the model you plan to use.

For most users, licensing only matters when downloading, modifying, fine-tuning, self-hosting, or redistributing model weights. For API-only use, the more immediate issues are model ID, pricing, data handling, uptime, and DeepSeek’s platform terms.

Privacy and data handling: what users should know

DeepSeek’s current privacy policy says it may collect personal data users provide directly, automatically collected data, and data from other sources. The policy specifically lists user inputs such as text input, voice input, prompts, uploaded files, photos, feedback, chat history, and other content provided to the model and services.

The same policy says DeepSeek may collect device and network data such as device model, operating system, IP address, device identifiers, system language, service logs, and approximate location based on IP address. It also says the services are not designed or intended to process sensitive personal data and that users should not provide sensitive personal data to the services.

DeepSeek’s privacy policy also says personal data may be used to operate, provide, develop, and improve the services, including improving and training its technology. It states that personal data may be shared with service providers, search-service integrations, analytics providers, safety-monitoring providers, and entities in DeepSeek’s corporate group for functions such as storage, content delivery, security, research and development, foundation model training and optimization, analytics, and support.

Retention is not described as zero-retention by default. DeepSeek says it retains personal data for as long as necessary to provide the services and for the other purposes set out in the policy, and that retention periods vary by data type, purpose, sensitivity, and legal requirements. The policy also says DeepSeek directly collects, processes, and stores personal data in the People’s Republic of China.

Practical privacy takeaway: Do not put sensitive personal data, confidential business information, regulated data, secrets, passwords, API keys, or private source code into DeepSeek unless your organization has approved that workflow and you understand the applicable data-processing terms.

Regulatory and government scrutiny

Government and regulator pages show why privacy cannot be treated as a footnote. South Korea’s Personal Information Protection Commission announced examination results for DeepSeek in April 2025 and recommended corrections and improvements related to cross-border transfer, transparency, deletion of certain transferred user-entered data, children’s data safeguards, and a domestic agent. Australia’s PSPF Direction 001-2025 requires Australian Government entities to prevent use or installation of DeepSeek products, applications, and web services on government systems and devices. Taiwan’s Ministry of Digital Affairs also announced restrictions for government agencies and critical infrastructure entities due to cybersecurity concerns, while Italy’s data protection authority ordered an urgent limitation on processing Italian users’ data in January 2025.

These official government actions do not mean DeepSeek is unusable for every individual or organization. They do mean any serious deployment should include a privacy, security, jurisdiction, and compliance review rather than relying only on model benchmarks or pricing claims.

Practical uses today

DeepSeek is most relevant today in five areas:

• General chat and writing: Use V4-Flash for fast and efficient everyday text tasks.
• Complex reasoning: Use V4-Pro or thinking mode when the task requires deeper multi-step analysis.
• Coding and agentic workflows: V4-Pro is the more natural starting point for demanding coding, agent, and long-context engineering work; V4-Flash is useful for simpler agent tasks and efficiency-sensitive coding assistance.
• Long-context work: V4’s 1M context makes DeepSeek more relevant for large documents, codebases, and multi-document workflows than older 128K-era pages suggested.
• Open-weight experimentation: Official model cards and open weights make DeepSeek relevant for researchers and teams evaluating self-hosting, but hardware and license checks remain essential.

DeepSeek’s strengths do not remove normal AI limitations. Outputs may be wrong, incomplete, or misleading. Tool calls and JSON output improve structure, but they do not make the model a source of truth. Validate important results independently.

How this page supports the rest of Chat-Deep.ai

This facts page is designed to support the main DeepSeek AI hub by giving users a current, source-based explanation of the DeepSeek ecosystem. For implementation details, use the updated DeepSeek API Guide. For model selection, use the updated DeepSeek Models page. For cost planning, use the DeepSeek Pricing page, the DeepSeek API Cost Calculator, and the official DeepSeek Models & Pricing page before making billing decisions. For launch details, see the DeepSeek V4 release tracker.

Conclusion

DeepSeek in April 2026 is best understood as a moving platform rather than a single static chatbot. The current official release line is DeepSeek-V4 Preview, the current API model IDs are deepseek-v4-flash and deepseek-v4-pro, and the old deepseek-chat / deepseek-reasoner names are legacy compatibility aliases on a retirement path. DeepSeek-V3.2 remains a major historical milestone, but it should no longer be presented as the current flagship API model.

For users and developers, the practical advice is simple: verify model names and API pricing against official DeepSeek docs and the official DeepSeek Models & Pricing page, treat older V3.2-era pages as historical unless updated, avoid sensitive data unless approved, and use V4 model IDs for any new production integration.