DeepSeek web app
The fastest door is a real conversation: open the community web chat, run one actual task, then decide Pro vs Flash or whether you need the API at all.
This page opens the community web chat, not chat.deepseek.com. Official clients and keys live on DeepSeek’s own site and open platform.
What the web app is
This site’s Start chat control sends you to the community web chat at app.deepseek.day. You talk in a browser. There is no SDK to install and no model string to paste into a request body. That is the right first step after searching DeepSeek, DeepSeek AI, or DeepSeek V4 — before you wire Claude Code, Harness, or Deep Code.
It is not the official DeepSeek client, not the API console, and not Hugging Face. If you only needed a conversation, stay here. If you are shipping a product, graduate to the DeepSeek API with the same V4 family. API keys belong to that API and to agent shells; they are not required to click Start chat on this community entry.
When to use the web app
Use it when you want signal, not plumbing:
- Try V4 on a real email, PDF, or coding question in minutes — not a hello-world prompt.
- Compare “does this feel like Pro or Flash?” before you commit a product to one model ID.
- Share a prompt with a teammate who does not want an API key yet.
- Decide whether you need the API at all, or whether a browser chat is enough for this week.
What the web app is not
Do not treat this door as the official stack:
- Not chat.deepseek.com and not the official DeepSeek desktop or mobile client.
- Not the DeepSeek API. There is no SDK and no model string in the chat UI.
- Not Hugging Face. You are not downloading weights from this page.
- Not Claude Code, Harness, or Deep Code. Those tools sit on the API after the prompt is stable.
Entry snapshot
- This door
- Community web chat at app.deepseek.day
- Not this door
- chat.deepseek.com / official client
- Chat UI
- No SDK, no model string to paste
- Start chat
- No API key required on this entry
- API keys
- For the API and agent shells only
- After a trial
- Pick Pro, Flash, or the API
How to start
One click from this site:
- Open the web app from the button above (or the header Start chat control). You land on app.deepseek.day, not chat.deepseek.com.
- Run one real task — a messy email, a PDF question, or a coding problem you actually have.
- Decide from that reply: stay in the browser, pick Pro vs Flash for volume, or copy the same instructions into the API / an agent shell.
- If you later need keys, create them on DeepSeek’s open platform. Do not expect this chat UI to ask for a key first.
Web vs API vs weights vs tools
Same V4 family, different doors. Open the one you actually need:
| Door | Role | When to open this page |
|---|---|---|
| Web app | Browser chat at app.deepseek.day | You want a real-task trial first |
| Official client | chat.deepseek.com and DeepSeek’s own apps | You specifically want the official chat |
| DeepSeek API | Hosted endpoint for products | You are shipping, not just chatting |
| Open weights | Checkpoints on Hugging Face | You must self-host or fine-tune |
| Claude Code / Harness / Deep Code | Agent shells on the API | The prompt is stable and you need a tool |
Boundaries and traps
- This is not the official DeepSeek chat. Bookmarks to chat.deepseek.com and keys from the open platform stay on DeepSeek’s own sites.
- Do not look for a model ID or SDK snippet in the chat UI. Those belong on the API page.
- An API key is not a login for Start chat here. Keys are for API calls and agent tools.
- A good web-app reply does not mean you picked the right product door. If you need automation, move to the API; if you need air-gapped inference, move to weights.
Related guides
FAQ
Is this the official DeepSeek chat?
No. Official chat is chat.deepseek.com and DeepSeek’s own clients. This page’s Start chat control opens the community web chat at app.deepseek.day via this site. Official accounts, official apps, and API keys are issued on DeepSeek’s own site and open platform — not inside this community entry.
Do I need an API key to click Start chat?
No. API keys are for the DeepSeek API and for agent shells (Claude Code, Harness, Deep Code). They are not required to open this community web chat. If a later product step needs a key, create it on the official open platform and use it against the API, not as a password for this page.
Which model does the web app use?
The V4 family — Pro for harder reasoning, Flash for everyday speed. Confirm the live selector in the app. When you graduate to the API, the IDs are deepseek-v4-pro and deepseek-v4-flash. The chat UI does not ask you to paste those strings.
Is the web app the same as the DeepSeek API?
No. The web app is a browser conversation. The API is a hosted endpoint you call from code. Same model family, different door. There is no SDK and no model string in the chat UI. If you are shipping a product, leave this page and use the API docs.
Can I drive Claude Code, Harness, or Deep Code from this chat?
Not from the chat box itself. Those tools call the DeepSeek API by default. Use the web app to stabilize a prompt, then point the tool at the API with a key from the official open platform. You do not download weights for that path.
When should I leave the web app?
After one real task, pick the next door on purpose. Stay here if a browser chat is enough. Move to the API if you need automation or a product. Fetch Hugging Face weights only if you must self-host, fine-tune, or keep inference off the public API.
Does this page replace DeepSeek’s official client or keys?
No. Official clients and keys stay on DeepSeek’s own site and open platform. This community entry is a try-then-decide door. Treat app.deepseek.day as the chat you opened from this site, not as a substitute for chat.deepseek.com or the official apps.