I fingerprinted Ox Alpha: same tokenizer as GLM-5.3 (+75 token offset), z.ai's exact error strings, near-identical temp-0 outputs

Reddit r/singularity 08/21/26, 12:43 PM Models

ai-model tokenizer fingerprinting glm-series model-comparison error-analysis

Summary

Through tokenizer comparison, error string analysis, and temp-0 output matching, the author concludes that Ox Alpha is likely based on the GLM-5.3 model, possibly a variant or updated version.

Ran three black-box fingerprint tests on stealth/ox-alpha (OpenRouter + OpenCode) vs public GLM-5.3 on z.ai. 1. Tokenizer: I sent 6 texts (EN/DE/CN/code/emoji) and compared prompt_tokens. Ox Alpha = GLM-5.3 exactly +75 on every text. Same tokenizer, constant 75-token hidden system prompt. Kimi/Qwen/MiMo/MiniMax all diverge. Counts identical on both Ox routes. 2. Error strings: Invalid reasoning_effort on Ox Alpha (OpenCode passes params through) returns: "[1210] This model always engages in thinking and cannot be disabled; please use low, high, or max", so the same as the GLM 5.3 error message 3. Temp-0 outputs: Greedy, same prompts → same markdown quirks, same German-decimal LaTeX (`0{,}375`), near word-for-word matches on factual answers. Qwen/MiMo/Kimi format these completely differently. Conclusion: I'm quite sure than Ox Alpha is a GLM model. Not sure if it's a vision variant of GLM 5.3 (GLM 5.3V) or a completely new version like GLM 5.5 but I guess it's unlikely that Z.AI drops 5.5 so early but idk. What are your thoughts?

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