GPT Image 2 vs GLM 5.1
| OpenAI GPT Image 2 | Z.ai GLM 5.1 | |
|---|---|---|
| Vendor | OpenAI | Z.ai |
| Context window | 128,000 | 200,000 |
| Max output | — | 128,000 |
| Reasoning | No | Yes |
| Tool calling | No | Yes |
| File input | Yes | No |
| Input | text, image | text |
| Output | image | text |
| Released | 2026-04-21 | 2026-04-06 |