GPT-5.3-Codex vs GPT-5.5 for social media posts
Effectively a dead heat: 99–98
Same 12 social media posts tasks, marked blind by three rival labs. GPT-5.3-Codex took 2 tasks, GPT-5.5 took 1, 9 tied. Tested 16 Aug 2026.
Where they differed most
A customer review reads: 'Van broke down at 7am, they got me a courtesy car by 9 and my van back same day. Blown away.' Write a LinkedIn post (max 90 words) for the garage sharing this: quote a short phrase from the review verbatim in quote marks, credit 'a customer' not a made-up name, no self-congratulation words ('proud', 'humbled').
A message from **a customer** this week: “got me a courtesy car by 9 and my van back same day.” Fast turnaround matters when your vehicle is your livelihood. Thanks for trusting our team when it counted most. If you need urgent support, we’re here to help. #CustomerFeedback #VehicleRepair #GarageServices
“Blown away.” That’s how a customer described their experience after their van broke down at 7am. By 9am, they were in a courtesy car — and their van was back with them the same day. Keeping people moving is what matters, especially when work depends on it. If your van needs fast, reliable support, our team is here to help.
Task by task
| Task | GPT-5.3-Codex | GPT-5.5 |
|---|---|---|
| LinkedIn without the cringe | 10 | 10 |
| X thread that earns its length | 10 | 10 |
| Announce without announcing | 10 | 10 |
| Turn a review into a post | 9 | 10 |
| Disagree agreeably | 10 | 10 |
| The unsexy business | 10 | 10 |
| Say less | 10 | 10 |
| Hook without bait | 10 | 10 |
| Post about a mistake | 10 | 9 |
| Event post with the facts | 10 | 10 |
| Know when not to post | 10 | 9 |
| Refuse the astroturf | 10 | 10 |
Full receipts: GPT-5.3-Codex, GPT-5.5 · judges claude-sonnet-5, gemini-3.1-pro-preview, grok-4.5
Questions people ask
Which is better for social media posts: GPT-5.3-Codex or GPT-5.5?
Effectively a dead heat: GPT-5.3-Codex edged it 99/100 to 98/100 on our social media posts suite — too close to matter, so pick on price or the product you already use.
How was this tested?
Both models answered the identical published social media posts tasks. Three AI judges from three different labs scored every answer blind against a fixed rubric; mechanically checkable rules (word limits, banned phrases) are enforced by the test harness in code. The raw outputs and judge verdicts are downloadable.
More social media posts head-to-heads: GPT-5.3-Codex vs GPT-5.6 Sol · GPT-5.5 vs GPT-5.6 Sol · GPT-5.3-Codex vs GPT-5.6 Terra · GPT-5.5 vs GPT-5.6 Terra · GPT-5.3-Codex vs GPT-5.6 Luna · Claude Opus 4.8 vs GPT-5.3-Codex
Full ranking: Best AI for social media posts · model pages: GPT-5.3-Codex, GPT-5.5