OpenAI: GPT-5.3-Codex vs Z.ai: GLM 5.1
Z.ai: GLM 5.1 wins on more metrics (5 of 9), but the right pick depends on what you optimize for — see the breakdown below.
| Metric | OpenAI: GPT-5.3-Codex | Z.ai: GLM 5.1 |
|---|---|---|
| Intelligence Index | 44.3✓ | 40.2 |
| Coding Index | — | 55.8✓ |
| GPQA Diamond | 92%✓ | 87% |
| Design Arena Elo | 1206✓ | — |
| Speed (tokens/sec) | 61 | 101✓ |
| Latency | 2.0s | 304ms✓ |
| Input price /M | $1.75 | $0.966✓ |
| Output price /M | $14.00 | $3.04✓ |
| Context window | 400K✓ | 203K |
| Capabilities | ReasoningToolsJSONVision | ReasoningToolsJSON |