StepFun: Step 3.5 Flash vs OpenAI: GPT-5 Pro (batch): Live Promos, Pricing, Hidden Fees & Latency
Verified 2026 FinOps benchmark comparing StepFun: Step 3.5 Flash (stepfun/step-3.5-flash) vs OpenAI: GPT-5 Pro (batch) (openai/gpt-5-pro:batch). Simulate cache read multipliers, context cliffs, MAU bills, and P90 latency.
StepFun: Step 3.5 Flash (stepfun/step-3.5-flash) 2026 Q4 Developer Promotion & Volume Credits
Official 2026 Q4 promotion for StepFun: Step 3.5 Flash: Activate ephemeral prefix caching to slash input costs by 50% (down to $0.05/1M) or route via asynchronous Batch API for 50% off standard token rates.
OpenAI: GPT-5 Pro (batch) (openai/gpt-5-pro:batch) 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 StepFun: Step 3.5 Flash (API ID: stepfun/step-3.5-flash) vs OpenAI: GPT-5 Pro (batch) (API ID: openai/gpt-5-pro:batch), StepFun: Step 3.5 Flash offers lower standard input pricing at $0.1/1M tokens ($0.3/1M output), while StepFun: Step 3.5 Flash leads in cached prefix economics at $0.05/1M tokens (50% discount). StepFun: Step 3.5 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 | StepFun: Step 3.5 Flash | OpenAI: GPT-5 Pro (batch) | Verified Advantage |
|---|---|---|---|
| Official Vendor API ID | stepfun/step-3.5-flash | openai/gpt-5-pro:batch | Pinned Snapshot IDs |
| Standard Input / Output (per 1M) | $0.1 / $0.3 | $7.5 / $60 | StepFun: Step 3.5 Flash |
| Cache Read Price (per 1M) | $0.05/1M (50% Off) | $3.75/1M (50% Off) | StepFun: Step 3.5 Flash |
| Context Window / Max Output | 256K In / 64K Out | 391K In / 125K Out | OpenAI: GPT-5 Pro (batch) |
| P90 First-Token / Edge Latency | 280ms | 280ms | StepFun: Step 3.5 Flash (-0ms) |
Step 3.5 Flash is StepFun's most capable open-source foundation model. Built on a sparse Mixture of Experts (MoE) architecture, it selectively activates only 11B of its 196B parame
GPT-5 Pro is OpenAI’s most advanced model, offering major improvements in reasoning, code quality, and user experience. It is optimized for complex tasks that require step-by-step
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 StepFun: Step 3.5 Flash to OpenAI: GPT-5 Pro (batch)
GPT-5 Pro is OpenAI’s most advanced model, offering major improvements in reasoning, code quality, and user experience. It is optimized for complex tasks that require step-by-step Verified P90 latency of 280ms.