GLM 5.1 vs GPT Image 2 Develop
| Z.ai GLM 5.1 | OpenAI GPT Image 2 Develop | |
|---|---|---|
| Vendor | Z.ai | OpenAI |
| Context window | 200,000 | 128,000 |
| Max output | 128,000 | — |
| Reasoning | Yes | No |
| Tool calling | Yes | No |
| File input | No | Yes |
| Input | text | text, image |
| Output | text | image |
| Released | 2026-04-07 | 2026-04-20 |