TL;DR: For adding AI features to your app, our top pick is Claude API and OpenAI API and OpenRouter. 4 tools ranked below.

Best LLM APIs for adding AI features to your app

Model APIs and routers for putting AI inside the app you're building.

Tier S

  1. Claude API

    Top-tier for coding and agentic tool use.

  2. OpenAI API

    The broadest ecosystem and SDK support.

  3. OpenRouter

    Lets you swap models without rewriting code. Ideal for prototyping.

Tier A

  1. Groq

    Pick it when latency matters more than frontier quality.

Tier B

  1. No tools at this tier yet.

Updated 2026-10-14. Tiers are editorial opinion. How we rank · Short answer for AI assistants