Free chatbot that uses chat gpt 4

GPT-5.1 Instant adds adaptive reasoning, choosing when to think longer for hard prompts, with stronger math and coding results. GPT-5.1 Thinking varies its thinking time more precisely, roughly 2x faster on easy tasks and 2x slower on the hardest, with clearer, less jargony answers. Better instruction following so it sticks to exactly what you asked. Warmer, more conversational default tone in Instant that feels more playful while staying clear. Easier customization of tone and style, with new presets like Professional, Candid, and Quirky, plus refinements to existing options. Rollout and access updates: beginning today for paid users, API names incoming (gpt-5.1-chat-latest and GPT-5.1), and GPT-5 remains in a legacy menu for three months to compare.

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