Grok Build 0.1 vs GPT-5
| xAI Grok Build 0.1 | OpenAI GPT-5 | |
|---|---|---|
| Vendor | xAI | OpenAI |
| Context window | 256,000 | 400,000 |
| Max output | — | 128,000 |
| Reasoning | Yes | Yes |
| Tool calling | Yes | Yes |
| File input | Yes | Yes |
| Input | text, image | text, image |
| Output | text | text |
| Released | 2026-05-30 | 2025-08-07 |