Z.ai: GLM 5.3 Flash vs OpenAI: GPT-5.1-Codex-Max: Live Promos, Pricing, Hidden Fees & Latency
Verified 2026 FinOps benchmark comparing Z.ai: GLM 5.3 Flash (z-ai/glm-5.3-flash) vs OpenAI: GPT-5.1-Codex-Max (openai/gpt-5.1-codex-max). Simulate cache read multipliers, context cliffs, MAU bills, and P90 latency.
Z.ai: GLM 5.3 Flash (z-ai/glm-5.3-flash) 2026 Q4 Developer Promotion & Volume Credits
Official 2026 Q4 promotion for Z.ai: GLM 5.3 Flash: Activate ephemeral prefix caching to slash input costs by 50% (down to $0.075/1M) or route via asynchronous Batch API for 50% off standard token rates.
OpenAI: GPT-5.1-Codex-Max (openai/gpt-5.1-codex-max) Startup Credits & Batch API 50% Off Promo
OpenAI GPT-6.1 Sol ($2/$10 base rate) qualifies for immediate 75% automatic prefix caching ($0.50/1M), 50% off 24-hour Batch API completions ($1/$5), and up to $150,000 in OpenAI/Azure Foundry credits via Microsoft for Startups Founders Hub (no VC funding required for initial tiers).
In Etuki October 2026 FinOps telemetry comparing Z.ai: GLM 5.3 Flash (API ID: z-ai/glm-5.3-flash) vs OpenAI: GPT-5.1-Codex-Max (API ID: openai/gpt-5.1-codex-max), Z.ai: GLM 5.3 Flash offers lower standard input pricing at $0.15/1M tokens ($0.5/1M output), while Z.ai: GLM 5.3 Flash leads in cached prefix economics at $0.075/1M tokens (50% discount). Z.ai: GLM 5.3 Flash achieves a 0ms faster P90 time-to-first-token latency (280ms vs 280ms).
Auto-discovered via live global telemetry registry.
Auto-discovered via live global telemetry registry.
| Specification / FinOps Dimension | Z.ai: GLM 5.3 Flash | OpenAI: GPT-5.1-Codex-Max | Verified Advantage |
|---|---|---|---|
| Official Vendor API ID | z-ai/glm-5.3-flash | openai/gpt-5.1-codex-max | Pinned Snapshot IDs |
| Standard Input / Output (per 1M) | $0.15 / $0.5 | $1.25 / $10 | Z.ai: GLM 5.3 Flash |
| Cache Read Price (per 1M) | $0.075/1M (50% Off) | $0.625/1M (50% Off) | Z.ai: GLM 5.3 Flash |
| Context Window / Max Output | 1024K In / 922K Out | 391K In / 125K Out | Z.ai: GLM 5.3 Flash |
| P90 First-Token / Edge Latency | 280ms | 280ms | Z.ai: GLM 5.3 Flash (-0ms) |
GLM-5.3-Flash is a native multimodal model from Z.ai. It is suited for efficient coding and long-horizon agent tasks. Its hybrid sparse and linear attention architecture maintains
GPT-5.1-Codex-Max is OpenAI’s latest agentic coding model, designed for long-running, high-context software development tasks. It is based on an updated version of the 5.1 reasonin
Real-Time Stack Cost & Hidden-Fee Simulator (MAU / Token / Egress / GMV)
Calibrated with Reddit r/FinOps & r/devops telemetry: Includes Context Caching, Bandwidth Egress, and MoR Tax
🛰️Switch from Z.ai: GLM 5.3 Flash to OpenAI: GPT-5.1-Codex-Max
GPT-5.1-Codex-Max is OpenAI’s latest agentic coding model, designed for long-running, high-context software development tasks. It is based on an updated version of the 5.1 reasonin Verified P90 latency of 280ms.