llm-fallback-chain

Private npm package. Provides a fallback chain across free LLM providers: Mistral → Groq → Gemini → OpenRouter

When one provider returns 429 / 503, the next one is tried automatically.

Install (from GitHub)

// package.json of your project
{
  "dependencies": {
    "llm-fallback-chain": "github:YOUR_USERNAME/llm-fallback-chain"
  }
}

npm install

Usage: Next.js (App Router)

app/api/chat/route.ts

import { createLLMChain } from 'llm-fallback-chain/node'

const llm = createLLMChain({
  providers: [
    { provider: 'mistral',    apiKey: process.env.MISTRAL_API_KEY! },
    { provider: 'groq',       apiKey: process.env.GROQ_API_KEY! },
    { provider: 'gemini',     apiKey: process.env.GEMINI_API_KEY! },
    { provider: 'openrouter', apiKey: process.env.OPENROUTER_API_KEY! },
  ],
  onFallback: (from, to, err) => {
    console.warn(`[llm] Falling back ${from} → ${to}:`, err.message)
  },
})

export const POST = llm.createNextHandler({
  systemPrompt: 'You are a helpful assistant.',
})

app/page.tsx

'use client'
import { LLMProvider, useLLMChat } from 'llm-fallback-chain/react'

function Chat() {
  const { messages, send, loading } = useLLMChat()

  return (
    <div>
      {messages.map((m, i) => <p key={i}><b>{m.role}:</b> {m.content}</p>)}
      <button onClick={() => send('Hello!')} disabled={loading}>
        {loading ? '...' : 'Send'}
      </button>
    </div>
  )
}

export default function Page() {
  return (
    <LLMProvider endpoint="/api/chat">
      <Chat />
    </LLMProvider>
  )
}

Usage: Expo / React Native

Same as React — hooks work identically. Just make sure endpoint points to your deployed API (not localhost in production).

<LLMProvider endpoint="https://your-api.vercel.app/api/chat">
  <YourScreen />
</LLMProvider>

Direct Node.js call (without HTTP)

import { createLLMChain } from 'llm-fallback-chain/node'

const llm = createLLMChain({ providers: [...] })

const result = await llm.call({
  messages: [{ role: 'user', content: 'Tell me a joke' }],
  systemPrompt: 'You are funny.',
  temperature: 0.9,
})

console.log(result.content, result.provider)

Build

npm install
npm run build   # outputs to dist/

Always commit dist/ — this is what gets installed in other projects.

Providers & Free Tiers

| Provider | Free tokens | Model (default) | |------------|------------------|----------------------------------------| | Mistral | 1B / month | mistral-small-latest | | Groq | rate-limited | llama3-8b-8192 | | Gemini | generous free | gemini-1.5-flash | | OpenRouter | multiple free | mistralai/mistral-7b-instruct:free |