Chat with GPT-4o mini for free
GPT-4o mini is the cheapest, fastest option in the family, built for simple, high-volume tasks where cost and speed win. Start typing, no sign-up needed.
See how GPT-4o mini 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-4o mini stand out
GPT-4o mini specifications
| Provider | OpenAI |
| Model family | GPT-4 series |
| Context window | 128,000 tokens |
| Max output | 16,384 tokens |
| Modality | Text · Vision · Code |
| Knowledge cutoff | October 2023 |
| Input price | $0.15 / 1M tokens |
| Output price | $0.6 / 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-4o mini vs other top models
| Model | Context | Best at | Input price | In Chatday |
|---|---|---|---|---|
| GPT-4o mini | 128K | Lightweight | $0.15/M | Free |
| Grok 4.6 | 500K | Agentic reasoning | $2/M | Free |
| Claude Opus 5 | 1M | Frontier agents | $5/M | Free |
| Gemini 3.1 Pro | 1M | Multimodal | $2/M | Free |
GPT-4o mini questions
Other models
Grok 4.6
Grok 4.6 is xAI's flagship for long agentic runs, with self-checking on multi-step tasks and strong coding at half frontier prices.
Claude Opus 5
Claude Opus 5 is Anthropic's strongest Opus model: hybrid reasoning for long-running agents, serious coding and computer use.
GPT-5.6
GPT-5.6 is OpenAI's newest flagship for hard, multi-step reasoning, coding and tool use, the default when problems get genuinely difficult.
Chat with GPT-4o mini and switch models any time.
One subscription, every leading model. Start free in the Chatday web app.