Question 1

What is the cheapest LLM API?

Accepted Answer

GPT-5 nano from OpenAI ranks first (blended price $0.138/M), followed by Qwen3.5-Flash ($0.175/M) and GPT-4.1 nano ($0.175/M). Ranked by blended list price per 1M tokens (3 input tokens to 1 output), cheapest first, among models the Respan Index ranks. Prices come from each provider's pricing page.

Question 2

How is this ranking made?

Accepted Answer

Ranked by blended list price per 1M tokens (3 input tokens to 1 output), cheapest first, among models the Respan Index ranks. Prices come from each provider's pricing page. The Respan Index combines published benchmark results, each linked to its source, and is updated as new results come out.

Question 3

Can I use these models through one API?

Accepted Answer

Yes. The Respan gateway serves models from every major provider behind one OpenAI-compatible API, with fallbacks when a provider fails.

Models

Models

Cheapest LLM APIs

FAQ

Best model for other jobs