Upstash

Upstash is a serverless data platform built for modern cloud and edge architectures. Its flagship product is serverless Redis — pay per request, no always-on servers, and a free tier generous enough for side projects. It integrates directly with Vercel, Cloudflare Workers, and Next.js, making it the default choice for rate limiting, session caching, and feature flags in AI apps. Upstash also offers Kafka for event streaming and QStash for durable message queuing with retries and scheduling. For AI builders, Upstash is particularly useful for throttling expensive LLM API calls, storing ephemeral conversation state, and queueing background inference jobs without managing infrastructure.