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OpenAI o1

Last updated 2026-07-11 · Reviewed by ToolForge Editorial

OpenAI's first reasoning model — it 'thinks' before answering, crushing math, science, and code benchmarks.

★ 4.8/5 · 100M+ users · Since 2024 · Limited in free tier
$20/mo ChatGPT Plus
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The model that reasons step by step

o1 was OpenAI's breakthrough 'deliberative' model. Instead of blurting the first token, it spends compute internally reasoning through the problem — which is why it leaps ahead on competition math, PhD-level science, and tricky coding. It's slower, but when correctness matters, it shows.

Who it's for: Researchers, competitive programmers, and anyone solving hard quantitative or logical problems where a wrong answer is costly.

Key features

🧠 Deliberative reasoning

Internal chain-of-thought before responding.

🧮 Math & science

Top scores on Olympiad and PhD-level benchmarks.

💻 Hard coding

Excellent on complex algorithmic problems.

⏱️ Slower by design

Traders time for accuracy — not chat speed.

The honest take

✓ What works

  • Best-in-class on hard reasoning tasks
  • Strong coding and proofs
  • Backed into ChatGPT/API

✗ What doesn't

  • Slower responses than GPT-4o
  • More expensive per token
  • Overkill for casual chat

Verdict

When the problem is hard and wrong answers are expensive, o1 earns its keep. For everyday chat, GPT-4o or o4-mini is faster and cheaper.

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$20/mo ChatGPT Plus · Limited in free tier

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