Chat with Claude Opus 4.8 for free
Claude Opus 4.8 is Anthropic's strongest model for coding, agentic tasks and enterprise work, with a 1M-token context window. Start typing, no sign-up needed.
See how Claude Opus 4.8 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 Claude Opus 4.8 stand out
Claude Opus 4.8 specifications
| Provider | Anthropic |
| Model family | Claude 4 series |
| Context window | 1,000,000 tokens |
| Max output | 128,000 tokens |
| Modality | Text · Vision · Code |
| Input price | $5 / 1M tokens |
| Output price | $25 / 1M tokens |
| Tool / function calling | Yes |
| Vision | Yes |
| Streaming | Yes |
| Available in Chatday | Free & Pro |
Pricing shown for reference; usage is included in your Chatday plan.
Claude Opus 4.8 vs other top models
| Model | Context | Best at | Input price | In Chatday |
|---|---|---|---|---|
| Claude Opus 4.8 | 1M | Frontier coding | $5/M | Free |
| GPT-5.5 | 1M | Flagship reasoning | $5/M | Free |
| Gemini 3.1 Pro | 1M | Multimodal | $2/M | Free |
| Grok 4 | 1M | Realtime | $0.2/M | Free |
Claude Opus 4.8 questions
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Gemini 3.1 Pro
Gemini 3.1 Pro is natively multimodal across text, image, audio and video, with the largest context window available and fast, fresh answers.
Grok 4
Grok 4 pairs realtime knowledge with a direct, witty tone and live web search, strong on current events and fresh information.
Chat with Claude Opus 4.8 and switch models any time.
One subscription, every leading model. Start free in the Chatday web app.