I need to swap model providers without changing my app code

You can do that by putting a provider-agnostic wrapper in front of your app and switching providers behind a stable interface.

Best approach

Use an abstraction layer so your app talks to one internal API, not directly to OpenAI / Anthropic / etc.

Options

1. Use an LLM gateway

   • Examples: LiteLLM, OpenRouter, Vercel AI Gateway, Portkey
   • Your app keeps the same request shape while the gateway routes to different providers.

2. Create your own adapter

   • Define a small internal interface like:
     • chat(messages, temperature, max_tokens, ...)
     • embeddings(texts)
     • moderation(input)
   • Implement one adapter per provider.

3. Use SDKs with compatible abstractions

   • Some frameworks normalize providers:
     • LangChain
     • LlamaIndex
     • Vercel AI SDK
   • Good if your app already uses them.

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What to standardize

To avoid app-code changes later, keep these stable:

• message format
• streaming behavior
• tool/function calling schema
• token limits
• error handling
• retry/timeouts
• model aliasing, e.g. fast-chat, best-chat, cheap-chat

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Recommended pattern

Use an internal config mapping:

• FAST_CHAT -> gpt-4o-mini or claude-haiku
• BEST_CHAT -> gpt-4.1 or claude-sonnet
• EMBEDDINGS -> text-embedding-3-large

Then switching providers is just config, not code.

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Example architecture

Your app → your internal client → gateway/adapter → provider

This lets you:

• change providers
• A/B test models
• fall back on outages
• route by cost/latency
• keep the app unchanged

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If you want the easiest path

• If you want minimal code changes: use LiteLLM or OpenRouter
• If you want full control: write your own thin adapter
• If you want framework support: use Vercel AI SDK or LangChain

If you want, I can give you:

1. a drop-in adapter design,
2. a LiteLLM setup, or
3. a provider-neutral interface example in your language.