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InactiveThis topic has no meaningful new developments right now.Updated Mar 18, 2026 · 12:00 AM
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ChatGPT Model Development Path

Latest development

GPT-5.x consolidated the stack into tiers

Key takeaways

  • The ChatGPT roadmap is no longer a simple GPT-3.5 to GPT-4 to GPT-5 ladder; users now experience a routed stack of flagship, reasoning, and fallback models.
  • Product changes increasingly happen through routing rules, retirements, and usage-tier fallbacks, so model access can change even when the chat UI looks the same.
  • The timeline shows capability gains coming from multimodality, RLHF and post-training, and specialized reasoning branches as much as from classic scale alone.

Timeline

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