I'm building a chat app with multiple model providers and want failover if one goes down; what should I use?

For a chat app with multiple model providers and automatic failover, you generally want an LLM gateway / router rather than talking to providers directly.

Best thing to use

1) A model gateway with fallback/routing

Look for a service or layer that can:

• send requests to multiple providers
• retry on errors/timeouts
• fail over to a backup model/provider
• optionally route by cost, latency, or quality
• normalize provider APIs into one interface

Examples in this category:

• OpenRouter
• LiteLLM
• Helicone (more observability-focused, but can help in the stack)
• Cloudflare AI Gateway (routing/observability pieces depending on setup)
• Other “LLM proxy/router” products

If you want to build it yourself

Implement a small abstraction layer:

1. Primary provider
2. Secondary provider(s)
3. Timeouts
4. Retries with backoff
5. Circuit breaker
6. Health checks
7. Fallback rules

Typical flow:

• Try Provider A
• If timeout / 5xx / rate limit, retry once or twice
• If still failing, switch to Provider B
• If B fails, try C
• Log which provider actually served the response

What to consider

Failover strategy

• Hard failover: only switch when the provider errors
• Soft routing: spread traffic across providers based on availability
• Per-model fallback: if GPT-4-class model fails, use a comparable model from another vendor
• Per-request policy: some requests may require a specific provider/model for compliance or quality

Important caveats

• Different providers have different:
  • system prompt handling
  • tool/function calling support
  • token limits
  • streaming behavior
  • moderation policies
• So “failover” is easier if you normalize your prompts and output handling.

My practical recommendation

If you want the fastest path:

• Use LiteLLM if you want to self-host a gateway/router and keep control.
• Use OpenRouter if you want a hosted unified API across many models.
• Add timeouts + retries + circuit breaker on top either way.

Simple rule of thumb

• Need control / self-hosting / enterprise routing → LiteLLM
• Need easiest multi-model access → OpenRouter
• Need observability + tracing around your stack → add Helicone or similar

If you want, I can sketch a reference architecture for your chat app or show a Python/Node failover wrapper.