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Overview

ModelStack provides access to models from three leading AI providers through a single API. All models use the OpenAI-compatible chat completions format.
Versioned model variants (e.g., claude-sonnet-4-5-20250929) are also supported. Any model with a supported prefix (claude-, gpt-, o1-, o3-, o4-, gemini-) is accepted.

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Anthropic

Model IDInput / 1M tokensOutput / 1M tokens
claude-opus-4-6$5.00$25.00
claude-opus-4-5$5.00$25.00
claude-opus-4-1$15.00$75.00
claude-sonnet-4-5$3.00$15.00
claude-sonnet-4-0$3.00$15.00
claude-opus-4$15.00$75.00
claude-haiku-4-5$1.00$5.00
claude-3-7-sonnet-20250219$3.00$15.00
claude-3-5-sonnet-20241022$3.00$15.00
claude-3-5-haiku-20241022$0.80$4.00
claude-3-haiku-20240307$0.25$1.25
Versioned variants also supported: claude-opus-4-5-20251101, claude-opus-4-1-20250805, claude-sonnet-4-5-20250929, claude-sonnet-4-20250514, claude-opus-4-20250514, claude-haiku-4-5-20251001

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OpenAI

Model IDInput / 1M tokensOutput / 1M tokens
gpt-4o$2.50$10.00
gpt-4o-mini$0.15$0.60
gpt-4-turbo$10.00$30.00
o1$15.00$60.00
o1-mini$1.10$4.40
o3$10.00$40.00
o3-mini$1.10$4.40
o4-mini$1.10$4.40
Versioned variants also supported: gpt-4o-2024-11-20, gpt-4o-mini-2024-07-18

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Google

Model IDInput / 1M tokensOutput / 1M tokens
gemini-2.5-pro$1.25$10.00
gemini-2.5-flash$0.15$0.60
gemini-2.0-flash$0.10$0.40
gemini-2.0-flash-lite$0.075$0.30
gemini-1.5-pro$1.25$5.00
gemini-1.5-flash$0.075$0.30

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Model Selection Guide

Best Quality

claude-opus-4-1 or o1 — Most capable models for complex reasoning, code generation, and nuanced tasks.

Best Balance

claude-sonnet-4-5 or gpt-4o — Excellent quality at moderate cost. Great for production workloads.

Best Speed

gemini-2.5-flash or gpt-4o-mini — Fast responses at low cost. Ideal for high-volume, latency-sensitive tasks.

Best Value

gemini-2.0-flash-lite or claude-3-haiku-20240307 — Lowest cost per token for budget-conscious applications.