Chat with DeepSeek V4 Flash for free
DeepSeek V4 Flash is a speed-tuned variant for everyday tasks and high-volume workloads at low cost. Start typing, no sign-up needed.
See how DeepSeek V4 Flash thinks
Pick a task and watch a sample answer stream in. Open the same prompt in Chatday when you’re ready.
The bug is in the arrow body: u.id = id assigns instead of compares, so the callback returns the assigned value and .find never matches the way you expect.
Fix it with a strict comparison:
Use === to compare. A single = is assignment, which is why you saw undefined.
What makes DeepSeek V4 Flash stand out
DeepSeek V4 Flash specifications
| Provider | DeepSeek |
| Model family | DeepSeek V4 series |
| Context window | 1,000,000 tokens |
| Max output | 384,000 tokens |
| Modality | Text · Code |
| Input price | $0.13 / 1M tokens |
| Output price | $0.26 / 1M tokens |
| Tool / function calling | Yes |
| Vision | No |
| Streaming | Yes |
| Available in Chatday | Free & Pro |
Pricing shown for reference; usage is included in your Chatday plan.
DeepSeek V4 Flash vs other top models
| Model | Context | Best at | Input price | In Chatday |
|---|---|---|---|---|
| DeepSeek V4 Flash | 1M | Fast | $0.13/M | Free |
| Gemini 4 Argon | 1M | Frontier coding | $2/M | Free |
| GPT-6.1 | 1.1M | Agentic coding | $2/M | Free |
| Claude Opus 5.5 | 1M | Flagship reasoning | $4/M | Free |
DeepSeek V4 Flash questions
Other models
Gemini 4 Argon
Gemini 4 Argon is Google's new frontier model for real-world coding and knowledge work, with a 1M-token window and long-form output.
GPT-6.1
GPT-6.1 is OpenAI's newest flagship for agentic coding, computer use and professional work, with a 1M-token context and configurable reasoning.
Claude Opus 5.5
Claude Opus 5.5 is Anthropic's new flagship for agentic coding and knowledge work, with a 1M-token context and lower prices than Opus 5.
Chat with DeepSeek V4 Flash and switch models any time.
One subscription, every leading model. Start free in the Chatday web app.