Reasoning assistant
How to use
DeepSeek.
Reasoning through technical questions, exploring code or mathematics, working with uploaded text, and comparing a second model’s approach.
DeepSeek is a general AI assistant and reasoning platform. Reasoning through technical questions, exploring code or mathematics, working with uploaded text, and comparing a second model’s approach. This guide covers the whole path in one place: official access, a first session that produces something reviewable, the checks that make output trustworthy, and the permissions worth limiting before you connect real work.
AI should make the work easier to inspect. If the workflow removes the source, the owner, or the review step, redesign the workflow.
Access & setup
Find, install, and sign in to DeepSeek
Get into the official DeepSeek experience with the right account and a setup you understand.
- 01
Start at https://chat.deepseek.com/ and confirm the domain before entering account or payment information.
- 02
Availability: Web browser plus official iOS and Android apps; DeepSeek does not document a native desktop application.
- 03
Use chat.deepseek.com on desktop. DeepSeek directs mobile users to its official App Store and Google Play listings and warns users to download only through official channels.
- 04
Sign in with the account you intend to keep using, then review plan, data, notification, and permission settings.
- 05
Run one low-risk test task before connecting sensitive files, repositories, or workspace data.
- Use official download pages.
- Review permissions during setup.
- Keep installers and applications updated.
First session
Your first useful DeepSeek session
Learn the interaction loop using a small task with a clear outcome.
- 01
Open the official web experience or mobile app and begin with a bounded, low-risk problem.
- 02
State the desired result, the available facts, and the constraints before asking for analysis.
- 03
Ask DeepSeek to expose assumptions and provide a concise answer after its reasoning work.
- 04
Check calculations, code, quotations, and current claims independently before using the result.
- State the outcome before the background.
- Provide the real source material.
- Review the result before expanding the task.
Quality control
Check the quality of DeepSeek output
Turn a plausible draft into work you are willing to stand behind.
- 01
Restate the original outcome and acceptance criteria before reviewing the response.
- 02
Mark every factual claim, calculation, quotation, or figure that could materially affect the result.
- 03
Check those items against the original source, a primary reference, or direct inspection.
- 04
Ask the tool to list its assumptions and uncertainty, but never rely on self-review as the only check.
- 05
Complete a human edit for relevance, tone, privacy, accessibility, and the exact delivery format.
- Verify consequential claims independently.
- Fluency is not accuracy; confident phrasing is not evidence.
- Keep a record of sources and review decisions.
Privacy & permissions
Use DeepSeek safely
Use the platform productively without giving it unnecessary access or authority.
- 01
Classify the task and its data before uploading or connecting anything.
- 02
Review the product, account, organisation, retention, and training settings that apply to you.
- 03
Grant the narrowest file, workspace, microphone, screen, or integration permissions needed.
- 04
Remove secrets and personal or regulated information unless your approved policy explicitly permits it.
- 05
Review the output and revoke permissions or disconnect sources that are no longer needed.
- DeepSeek can produce convincing but incorrect explanations. Product access, model selection, search, and file features can change; verify consequential output and review the current privacy terms before sharing sensitive material.
- Follow your organisation's approved-use policy.
- Never treat fluent output as authorization to act.
Models & pricing
What DeepSeek costs, model by model.
DeepSeek competes almost entirely on price, undercutting comparable Western models by several multiples at similar capability tiers.
| Model | Role | Input | Output |
|---|---|---|---|
| DeepSeek-V4-Pro | Higher-capability tier | $0.435 | $0.87 |
| DeepSeek-V4-Flash | Fast, high-volume tier | $0.14 | $0.28 |
Figures verified 2 September 2026 against DeepSeek API pricing ↗. Model pricing changes frequently — confirm before you budget.
| Provider | Frontier tier | Balanced default | Low-cost tier |
|---|---|---|---|
| OpenAI | GPT-5.6 Sol — $5 / $30 | GPT-5.6 Terra — $2 / $12 | GPT-5.6 Luna — $0.20 / $1.20 |
| Anthropic | Fable 5.1 — $10 / $50 | Sonnet 5 — $2 / $10 | Haiku 4.5 — $1 / $5 |
| Gemini 3.1 Pro — $2 / $12 | Gemini 3.1 Pro — $2 / $12 | Gemini 3.5 Flash-Lite — $0.15 / $1.25 |
Cross-provider comparison verified 2 September 2026. Sources: OpenAI API pricing ↗ · Claude platform pricing ↗ · Gemini API pricing ↗
Common questions
DeepSeek questions people actually ask.
Why is DeepSeek so much cheaper?
DeepSeek-V4-Pro runs $0.435 input / $0.87 output per million tokens, roughly a third of comparable models in the same capability band. Before switching production workloads, confirm where requests are processed and retained, and whether that satisfies your own or your client's data policy — the cost saving is real, but so is the governance question.
Core workflows
Step-by-step ways to use DeepSeek for the work it does best.
Each workflow below has its own outcome, steps and review checkpoints.
Structure a difficult coding, mathematics, or systems question so the reasoning can be checked rather than merely admired.
↓ 02 WorkflowReview and improve code with DeepSeekUse DeepSeek as a code-review partner while keeping repository conventions, security, and testing under human control.
↓Workflow 01
Reason through a technical problem with DeepSeek
Structure a difficult coding, mathematics, or systems question so the reasoning can be checked rather than merely admired.
Outcome: Reach a technically useful answer whose assumptions and calculations are visible.
- 01
State the problem in your own words, including known inputs, constraints, and the exact unknown.
- 02
Ask DeepSeek to identify missing information and ambiguous definitions before solving.
- 03
Request a short proposed method, then inspect whether that method fits the problem.
- 04
Have it work through the solution with named assumptions and intermediate checks.
- 05
Recalculate critical steps, run the code, or compare the result with an authoritative reference.
What good use looks like
- Separate the method from the answer.
- Test boundary cases.
- Ask a second model or person to challenge the result.
Workflow 02
Review and improve code with DeepSeek
Use DeepSeek as a code-review partner while keeping repository conventions, security, and testing under human control.
Outcome: Produce a focused improvement that survives review and execution.
- 01
Provide the smallest complete code sample plus its language, runtime, expected behavior, and failure.
- 02
Ask for diagnosis before requesting rewritten code.
- 03
Require the response to distinguish correctness bugs, security risks, performance concerns, and style preferences.
- 04
Apply one change at a time and compare the new behavior with the original acceptance criteria.
- 05
Run tests, static analysis, and a manual review in the real project before accepting the suggestion.
What good use looks like
- Never paste secrets.
- Keep project context authoritative.
- Reject rewrites that change behavior without explanation.
Official references
Check the current product documentation.
Features, plan limits, availability, and data controls change. These official pages are the starting points used for this guide.