GLM 5.3 FlashX Legal
GLM-5.3-FlashX-Legal (GLM-Legal) is Z.ai's legal-domain variant of GLM-5.3-FlashX, a native multimodal model that accepts text, image, and video input and produces text.
Specifications
| Lab | Z.ai |
|---|---|
| Context window | 1M tokens |
| Input price | $0.37/1M |
| Output price | $1.25/1M |
| Release | Oct 2026 |
Strengths
- Legal-domain mid-training plus RL post-training: 19.2% all-criteria pass rate on Harvey LAB, +12.5pp over the base model
- Matches frontier models on LegalBench and PLawBench (vendor-reported)
- 1M-token context window for long contracts and evidence bundles
- Native text, image, and video input for scanned documents and exhibits
Weaknesses
- Narrow vertical specialization; general coding and open-domain work trail the base FlashX
- Accuracy claims rest on vendor-reported legal benchmarks with no broad independent reruns yet
- Best results need Z.ai legal MCP integrations and an agent harness, not plain chat
Best for
- Contract review and redlining
- Legal research and compliance checklists
- Evidence analysis across long document sets
In Depth: GLM 5.3 FlashX Legal
Summary
GLM 5.3 FlashX Legal is an AI model from Z.ai.
Released in Oct 2026. It takes text, image, and video input and produces text output, with a context window of 1M tokens. Input pricing is $0.37 per 1M tokens and output is $1.25 per 1M tokens on OpenRouter.