Chat with GPT-5 for free
GPT-5 is the dependable baseline of the GPT-5 family, a capable, well-rounded model for a broad range of general tasks. Start typing, no sign-up needed.
See how GPT-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 GPT-5 stand out
GPT-5 specifications
| Provider | OpenAI |
| Model family | GPT-5 series |
| Context window | 400,000 tokens |
| Max output | 128,000 tokens |
| Modality | Text · Vision · Code |
| Input price | $1.25 / 1M tokens |
| Output price | $10 / 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.
GPT-5 vs other top models
| Model | Context | Best at | Input price | In Chatday |
|---|---|---|---|---|
| GPT-5 | 400K | General | $1.25/M | Free |
| Claude Opus 4.8 | 1M | Frontier coding | $5/M | Free |
| Gemini 3.1 Pro | 1M | Multimodal | $2/M | Free |
| Grok 4 | 1M | Realtime | $0.2/M | Free |
GPT-5 questions
Other models
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GPT-5.5
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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.
Chat with GPT-5 and switch models any time.
One subscription, every leading model. Start free in the Chatday web app.