Theo Pro
Theo Pro is the higher-quality conversational engine — used for hard reasoning, code, and modes where correctness and depth matter more than latency.
In depth
Theo Pro powers Think Mode and the heavier paths in Code Mode and Research. It’s slower and more expensive than Theo, but produces tighter, better-cited, and better-structured outputs.
Also known as
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See enginesRelated terms
Theo (Chat Engine)
Theo is the default conversational engine — fast, capable, and tuned for everyday chat, drafting, and lightweight tool calling.
Theo Reason
Theo Reason is the deep-thinking engine — extended-deliberation reasoning for hard math, plans, and analysis tasks.
Think Mode
Think Mode runs Theo’s deep reasoning engine — slower but with better answers for hard problems, multi-step plans, and code or analysis tasks where correctness matters.