Introduction to OpenAI's o3 and o4-mini Models
OpenAI has just rolled out two new reasoning engines—o3 (the heavyweight) and o4-mini (its faster, lighter sibling). Both can “think with images”, run Python mid‑conversation, and call external tools, but o4-mini does it for about 1⁄10 the price. Pair them with the new Codex CLI for terminal‑based coding help, or check out Anthropic’s Claude Code if you want deeper Git integration. Here’s the ultra‑short tour of these updates.
Meet the Models
| o3 | o4-mini | |
|---|---|---|
| Super‑power | Deep chain‑of‑thought, 200k‑token context | 80–90% of o3’s brains, lower latency |
| Image skills | Reads diagrams, zooms/rotates to reason | Same vision stack, great with messy photos |
| Typical use | Big math, giant codebases, research agents | Everyday dev work, high‑volume vision tasks |
Power vs. Price (why your CFO smiles at o4-mini)
- o3: $10/M input · $40/M output tokens
- o4-mini: $1.10/M input · $4.40/M output tokens
In practice, you keep roughly 85% of the capability for about a tenth of the bill.
Where Each Model Shines
o3 – the deep thinker
- Crushes benchmarks: 71% on SWE‑bench‑Verified bug‑fix tasks, 95%+ on AIME math.
- Handles 200k‑token prompts—enough for an entire repo or PhD thesis.
- Runs Python while reasoning to test hypothesis and QA its own solutions.
o4-mini – the cost‑effective sprinter
- Same multimodal tricks, optimized for speed and price.
- Surprisingly robust with blurry, low‑light, or skewed images.
- Ideal for batch OCR, support‑chat summarization, and any “do this 10 k times an hour” workload.
Codex CLI vs. Claude Code — two terminal coding tools
| Feature | Codex CLI | Claude Code |
|---|---|---|
| Install | npm i -g @openai/codex |
pip install claude-code (private preview) |
| Speed | 2–3× faster iterations | Slower but “thinks harder” |
| Autonomy modes | Suggest ▸ Auto‑Edit ▸ Full‑Auto | Interactive ▸ Headless |
| Git magic | Basic diff explanations | PR creation, merge conflict fixes |
| Privacy | All code stays local; only prompts hit OpenAI | Local for terminal; browser tool runs JS sandbox |
When to use each tool
Choose Codex for rapid refactors and local privacy; pick Claude when you need in‑depth reasoning plus advanced Git workflows.
Try Them in Five Minutes
ChatGPT UI
- Plus/Pro/Team users: click the model picker and choose o3 or o4-mini.
- Free tier: switch to Think mode to sample o4-mini.
API One‑Liner
curl https://api.openai.com/v1/chat/completions \
-H "Authorization: Bearer $OPENAI_API_KEY" \
-d '{
"model": "o4-mini",
"messages": [{"role":"user","content":"Summarize today\'s AI news in 5 bullets"}]
}'
Note: For API access of o3 you may need to submit some documents for verification. Check OpenAI's official note for more details.
Codex CLI Quick Demo
codex "Convert this JSON API response into TypeScript types"
TL;DR
Need raw brainpower? Pick o3.
Need scale on a budget? Pick o4-mini.
Whichever you choose, pairing them with Codex CLI or Claude Code turns the models into hands‑on coding copilots.
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