api

LocalAI

An open-source drop-in replacement for the OpenAI API that runs models on your own hardware, including CPU-only machines. MIT licensed.

From the site: LocalAI is the open-source AI engine. Run any model - LLMs, vision, voice, image, video - on any hardware. No GPU required. - mudler/LocalAI

Why I recommend it: Point existing code at your own server instead of a paid API — no code changes beyond the address.

OpenRouter

One interface to hundreds of AI models with prices side by side, including a set of free models you can use without a subscription.

From the site: The unified interface for every model. Find the best models & prices for your prompts

Why I recommend it: Free to sign up and there are free models on the list; paid models are pay-as-you-go with no subscription.

OpenAI Realtime Voice Prompting Guide

Official OpenAI guide for designing prompts for Realtime voice models, including gpt-realtime-2 and gpt-realtime-1.5. Covers role definition, guardrails, tool delegation and iterative testing.

Why I recommend it: Start here if you are building voice agents or want cleaner spoken-AI interactions. The guide recommends starting minimal and adding rules only for behaviors that fail in testing.