Olmo 3 (AI2)
Free tier available
- Self-hosted (Apache 2.0 + fully open data)$0
- API via partner providersUsage-based/per 1M tokens
B
7.9/10Olmo 3 (AI2)
VS
Our pickA
8.3/10Codex (OpenAI)
GPT-5.2-Codex (default 2026-04-23) / GPT-5.5 / GPT-5.4
Olmo 3 (AI2) vs Codex (OpenAI)
Tier-list head-to-head. Codex (OpenAI) takes the A-tier slot — here's the breakdown.
Last reviewed April 25, 2026· sweep-fresh
Spec sheet
At a glance
| Olmo 3 (AI2) | Codex (OpenAI) | |
|---|---|---|
| Tier | B-tier | A-tierwin |
| Overall score | 7.9 / 10 | 8.3 / 10win |
| Powered by | — | GPT-5.2-Codex (default 2026-04-23) / GPT-5.5 / GPT-5.4 |
| Free tier | Yes | Yes |
| Starting price | $0 | $0 |
| Best for | AI researchers doing reproducibility work, training-data studies, instruction-tuning research, or RLHF-free… | Developers already paying for ChatGPT Plus who want a coding agent at no extra cost. |
| Last reviewed | 2026-04-17 | 2026-04-25 |
Head-to-head
Score showdown
Rated 1-10 on the same rubric across all 130 tools we cover.
Ease of use+2.0 Codex (OpenAI)
Olmo 3 (AI2)
6.0
Codex (OpenAI)
8.0
Output qualityTie
Olmo 3 (AI2)
8.0
Codex (OpenAI)
8.0
Value+1.5 Olmo 3 (AI2)
Olmo 3 (AI2)
9.5
Codex (OpenAI)
8.0
Features+1.0 Codex (OpenAI)
Olmo 3 (AI2)
8.0
Codex (OpenAI)
9.0
Overall+0.4 Codex (OpenAI)
Olmo 3 (AI2)
7.9
Codex (OpenAI)
8.3
What you'll pay
Pricing snapshot
Look past the headline number -- entry-tier limits drive most cost surprises.
Codex (OpenAI)
Free tier available
- Free$0
- Go$8/mo
- Plus$20/mo
Benchmark Head-to-Head
GPT-5.2-Codex (launched 2026-04-23 -- SOTA on SWE-Bench Pro and Terminal-Bench 2.0; first-party scores below pending detailed third-party verification) benchmarks — Olmo 3 (AI2) has no published benchmarks
| Benchmark | Description | Score |
|---|---|---|
| SWE-bench | Real GitHub issue fixing | 72% |
| HumanEval | Python code generation | 95% |
The decision
Which should you pick?
Use-case anchors and category strengths, side by side.
Pick Olmo 3 (AI2)if…
B
7.9/10- ✓Better value at the price you'll actually pay (9.5/10 on value)
- ✓AI researchers doing reproducibility work, training-data studies, instruction-tuning research, or RLHF-free (RLZero) experimentation.
- ✓Also valuable for academic institutions and non-profits that want to use an open-weight model whose provenance is fully auditable.
AI researchers doing reproducibility work, training-data studies, instruction-tuning research, or RLHF-free (RLZero) experimentation. Also valuable for academic institutions and non-profits that want to use an open-weight model whose provenance is fully auditable. Good as a teaching / learning model where inspecting checkpoints matters.
Visit Olmo 3 (AI2)Pick Codex (OpenAI)if…
A
8.3/10- ✓Easier to learn and use day-to-day -- friendlier onboarding curve
- ✓More feature surface area for power users who'll use the depth
- ✓Developers already paying for ChatGPT Plus who want a coding agent at no extra cost.
- ✓Especially good for parallel task execution -- assign multiple bug fixes or feature branches and let Codex work them simultaneously.
Developers already paying for ChatGPT Plus who want a coding agent at no extra cost. Especially good for parallel task execution -- assign multiple bug fixes or feature branches and let Codex work them simultaneously.
Visit Codex (OpenAI)Bottom line
The verdict
Codex (OpenAI) edges out Olmo 3 (AI2) by 0.4 points (8.3 vs 7.9) -- a A-tier vs B-tier split that's narrow but real. Not a blowout; both belong on a shortlist. The score gap shows up most clearly in the categories that matter for Codex (OpenAI)'s strengths, so if those categories are your priority, the lead translates.
Pricing-wise, both tools have a free tier (Olmo 3 (AI2) starts $0, Codex (OpenAI) starts $0), so you can test either without committing. Compare what each free tier actually unlocks -- usage caps, model access, and feature gates differ a lot more than the headline price suggests, especially as both vendors have tightened limits in 2026.
By use case: pick Olmo 3 (AI2) when ai researchers doing reproducibility work, training-data studies, instruction-tuning research, or rlhf-free (rlzero) experimentation. Pick Codex (OpenAI) when developers already paying for chatgpt plus who want a coding agent at no extra cost. The two tools aren't fighting for the same person -- they're aiming at adjacent jobs that occasionally overlap. If you're squarely in Codex (OpenAI)'s lane, the tier-list ranking and the use-case fit point the same direction; if you're in Olmo 3 (AI2)'s lane, the score gap matters less than the fit.
Bottom line: Codex (OpenAI) is the safer default for most readers, but Olmo 3 (AI2) is competitive enough that the tie-breaker is your specific workload, not the spec sheet.
Keep digging
Compare more & explore
Full Olmo 3 (AI2) review
Tier B · 7.9/10
Full Codex (OpenAI) review
Tier A · 8.3/10
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Built from our daily AI-tool sweep, last touched April 25, 2026. Honest tier-list reviews — no affiliate-link pieces disguised as advice. See the rubric or how we review.