LLM APIs · S-tier

OpenAI API

Usage-based API for GPT models, images, and audio. The default when a product needs a frontier model.

External model signals

OpenAI API is scored here as a product. Two public boards rank the models it serves. Token usage informs momentum. Blind votes inform capability. Their numbers stay on their sites.

OpenRouter rankings. OpenRouter ranks models by tokens processed through the OpenRouter API. OpenRouter states that a higher token total shows how much a model is used, not which model is best for a task. That usage informs momentum.
Arena (LMArena leaderboard). Arena, also called LMArena, ranks models by blind human votes. People compare anonymous answers, and only those anonymous votes count toward the public board. Arena fits the votes with a Bradley-Terry model. Those votes inform capability. Method: Arena FAQ.

Checked 14 Oct 2026. The OpenRouter rankings page showed usage through 13 Oct 2026. Rankings data is licensed CC BY 4.0. The figures move, so StackPick links the boards. Rankings data: CC BY 4.0. How these boards enter the score.

Best for

Products that want the broadest model, tool, and SDK support.

What it is

The OpenAI API is the usage-based platform for GPT models plus image and audio endpoints. It is the default integration when a product needs a widely supported frontier model and the usual SDK examples. New accounts sometimes get credits; ongoing use is paid.

apigptusage-basedLLM APIs

Score breakdown

Capability 40%96
Ease 25%86
Value 20%80
Momentum 15%95

Pricing

Paid

Starting price: check site

Usage-based. Introductory credits come and go. Budget from the pricing page, not from memory.

Dates

Released Jun 2020 (month precision).

Added to StackPick 14 Oct 2026.

Alternatives

A-tier · 88

Anthropic API

Production apps that want Claude specifically, especially for long documents and code.

A-tier · 88

Gemini API

Apps that want Gemini, multimodal inputs, and a real free tier to prototype.

A-tier · 87

OpenRouter

Switching models without rewriting the client, or failing over when one lab is down.

Comparisons

vs Anthropic API vs Gemini API

Questions

What is OpenAI API best for?

Products that want the broadest model, tool, and SDK support.

How much does OpenAI API cost?

Paid. Starting price: check site. Usage-based. Introductory credits come and go. Budget from the pricing page, not from memory.

What are alternatives to OpenAI API?

Anthropic API, Gemini API, OpenRouter are the alternatives we file next to it. Open a comparison when one exists.

How do model leaderboards relate to OpenAI API?

OpenAI API is scored here as a product. OpenRouter rankings (https://openrouter.ai/rankings) inform momentum from token usage. Arena (https://arena.ai) informs capability from blind votes on the models it serves. Figures stay on those sites.