Chat with Claude Opus 5.5 for free
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. Start typing, no sign-up needed.
See how Claude Opus 5.5 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 5.5 stand out
Claude Opus 5.5 specifications
| Provider | Anthropic |
| Model family | Claude 5 series |
| Context window | 1,000,000 tokens |
| Max output | 128,000 tokens |
| Modality | Text · Vision · Code |
| Input price | $4 / 1M tokens |
| Output price | $20 / 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 5.5 vs other top models
| Model | Context | Best at | Input price | In Chatday |
|---|---|---|---|---|
| Claude Opus 5.5 | 1M | Flagship reasoning | $4/M | Free |
| Gemini 4 Argon | 1M | Frontier coding | $2/M | Free |
| GPT-6.1 | 1.1M | Agentic coding | $2/M | Free |
| Grok 4.7 | 500K | Agentic coding | $2/M | Free |
Claude Opus 5.5 questions
Other models
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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.
Grok 4.7
Grok 4.7 is xAI's most capable model for coding and knowledge work, built for multi-hour tasks at the same price as Grok 4.6.
Chat with Claude Opus 5.5 and switch models any time.
One subscription, every leading model. Start free in the Chatday web app.