AI gateway, observability and guardrails for production LLM apps
PromptMule has permanently shut down with its domain offline and returning DNS resolution failures.
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Verified active tools in AI Developer Tools, ranked by current traffic and editorial score.
AI gateway, observability and guardrails for production LLM apps

Open models served fast, with warm-cache routing for agents
One OpenAI-compatible gateway for adaptive LLM routing, guardrails, and spend control
Free / Open-sourceOpen-source LLM observability and AI gateway for shipping reliable AI apps

One OpenAI-compatible key for discounted GPT, Claude and Gemini access
Free / Open-sourceOne OpenAI-compatible API to route, monitor and control 250+ LLM models
PromptMule was an API cache-as-a-service platform built specifically for generative AI application developers. It optimized API costs and latency through intelligent cloud caching of LLM requests.
Since PromptMule is completely offline, explore the active AI developer APIs and LLM cost optimization tools listed at the top of this page.
Open models served fast, with warm-cache routing for agents
One OpenAI-compatible gateway for adaptive LLM routing, guardrails, and spend control
Free / Open-sourceOpen-source LLM observability and AI gateway for shipping reliable AI apps
Free / Open-sourceOne OpenAI-compatible API to route, monitor and control 250+ LLM models