a2ui-free is an open-source, provider-agnostic LLM factory for developers who want to build on free-tier models without hard-wiring a vendor.

It exposes a single client interface over roughly 90 free models across OpenRouter, Groq, Google AI Studio, Cloudflare Workers AI and other providers, and a weekly cron probe that exercises every model, records latency and failure modes, and prunes dead endpoints automatically, so the catalog stays honest without manual upkeep.

Key engineering features:

- One factory interface, many providers: swap models by name, not by rewriting call sites

- Weekly automated liveness probe with per-model latency and error tracking

- Capability tags (context window, tool use, JSON mode) so callers can select by need

- Zero-cost by design: only free-tier endpoints, with fallbacks when a provider rate-limits

Source and docs: https://github.com/kiragu-maina/a2ui-free