LLM-Kit — Supabase-native LLM starter with cost tracking & prompt ops built in
Stop bolting on Langfuse. Next.js 15 + Supabase + Claude/Gemini/OpenAI. Ship an LLM SaaS foundation in a day — prompt versioning, A/B, and real cost visibility included.Every LLM boilerplate ships auth, billing, and a landing page. None ship what decides whether your LLM app survives production: cost visibility and prompt operations.LLM-Kit bundles the three things no buyable kit does, Supabase-native:Prompt ops in your DB — versioned history, label-based deploy (swap prod/staging, no redeploy), weighted A/B with stable per-user assignment, admin UI, playground, version diff.Cost tracking + guardrails — per-feature / per-user token & cost logging, daily spend caps and rate limits that actually block, Slack-compatible alerts.Reliability — provider fallback with exponential backoff retry, JSON-schema structured output.In our own A/B test, picking the winning version cut cost ~53x ($0.046 to $0.00087 per call) and latency ~3x — the results view shows this on real traffic, automatically.Provider abstraction (Claude/Gemini/OpenAI via one env var) is included — table stakes in 2026, not the point.One function ties it together: runPrompt({ slug, variables, userId, feature }) resolves A/B, generates, logs cost. Auth (Supabase), API-key protection, RLS, admin login, and a passing test suite are wired.Ships as: full source, docs/RECIPES.md (11 recipes), CHANGELOG, llms.txt, npm run check-env setup checker.What it is / isn't: this is the backend ops foundation + admin dashboard for YOUR app — not a finished end-user product. No end-user chat UI, no billing, no streaming (roadmap). Docs and admin UI are English/Japanese.Starter ($99): full source + docs. License: your own products, 1 developer.Pro ($199): + a 33-page implementation guide (EN/JA) covering every design decision, a 50-prompt production pack (EN/JA) with one-shot idempotent DB import, and a license that also covers client work you personally deliver.Team ($399): + company-wide license (all your developers, unlimited client work), a standalone license certificate for your records, and priority support.Upgrade anytime — pay only the difference (message me with your order ref).
Get it → soulfire512.gumroad.com