ChatGPT (GPT-5.5)
OpenAI's closed flagship with the strongest agentic coding scores and the largest production ecosystem.
ChatGPT (GPT-5.5) vs
DeepSeek V4-Pro
ChatGPT vs DeepSeek
OpenAI's closed-source GPT-5.5 vs DeepSeek's 1.6T-parameter MoE V4-Pro — frontier intelligence vs cost-effective open-weight power.
DeepSeek V4-Pro
DeepSeek's 1.6T-parameter MoE flagship with hybrid attention, 73% inference savings vs V3.2, and open availability.
| ChatGPT (GPT-5.5) | DeepSeek V4-Pro | |
|---|---|---|
| Latest flagship | GPT-5.5 | DeepSeek V4-Pro |
| Architecture | Closed | MoE 1.6T total / 49B active |
| Context window | 256K | 1M |
| Open weights | No | Available via DeepSeek |
| Cost | OpenAI tiers | Significantly lower per-token |
| Best at | Agentic coding, ecosystem | Cost-efficient reasoning at scale |
Pick GPT-5.5 when you want the leading closed-source flagship and OpenAI's tooling ecosystem.
Pick DeepSeek V4-Pro when cost matters, you need a 1M-token context, or you want to self-host an open MoE model.
The verdict
GPT-5.5 leads on raw agentic coding quality. DeepSeek V4-Pro is the price-performance leader and the best self-hostable flagship.
Frequently Asked Questions
Is DeepSeek really cheaper than ChatGPT?
Yes — DeepSeek V4 cuts inference FLOPs by ~73% vs V3.2 and is priced well below GPT-5.5 / Opus 4.7.