LLM router comparison: OpenRouter, LiteLLM and more
Short answer: pick a router when you want the model chosen for you, request by request, from evidence about what each model can do. Pick a gateway when your main need is model coverage, self-hosting, or one key and one bill. Emissary is a router that also works as a gateway. This page puts it next to four other options. Each has its own detailed page, linked below.
Based on public information as of October 2026. Check each vendor's site for current details.
How do Emissary, OpenRouter, LiteLLM, Not Diamond and Router.com compare?
| Emissary | OpenRouter | LiteLLM | Not Diamond | Router.com | |
|---|---|---|---|---|---|
| Category | Router, with a gateway | Unified API and marketplace with provider routing | Open-source gateway and proxy, with a routing layer | Model routing company: an API router, and a local proxy for coding agents | Ramp's LLM routing layer: a gateway with pluggable routing policies |
| How the model is chosen | A router trained on rollouts predicts, per model and effort, whether it can complete the task, then picks the cheapest confident one, taking cache state, output length and effort into account | You choose the model, and it routes across providers. An auto-router option (openrouter/auto) picks among models | You write rules and config: model groups, weights, fallbacks | The API router recommends a model. Not Diamond Code routes from derived metadata such as a complexity classification | Its own cheapest-approved-model-above-a-quality-bar strategy, or another policy you plug in |
| Who executes the call | Emissary's gateway, on your provider keys | OpenRouter, billed through credits | The proxy you host | Your application, for the API router. A local proxy, for Not Diamond Code | Router.com, as one endpoint across providers |
| Strength | Routing decisions grounded in model capability and cost, with tracked savings | Breadth of models behind one key and one bill | Near-complete model coverage, and self-hosting | Routing from metadata alone, without request content | Finance integration and spend controls |
Which LLM router should I choose?
- You want the model chosen automatically for each request, with quality protected by a confidence threshold: Emissary.
- You want the broadest model coverage in a self-hosted gateway, and your routing is simple enough to manage as rules: LiteLLM.
- You want a wide catalog behind one API key and one bill, and your main need is availability and price across providers for models you've already chosen: OpenRouter.
- You want routing that works only from metadata, or a local proxy for a coding agent: Not Diamond.
- Finance integration is the priority, with inference spend flowing into Ramp's reporting: Router.com.
What does "routing" mean across these products?
The word covers different jobs. Provider routing chooses which provider serves a model you already picked. Reliability routing is load balancing, retries and fallbacks. Model routing chooses which model should serve each request. Most gateways do the first two and some offer a version of the third. See routers and gateways and the router design space.
How should I evaluate any router?
Whichever products you shortlist, test on your own requests rather than on a vendor's figures. Use the router selection checklist to decide what matters for your workload, and run a trial on your traffic to measure cost, latency and quality against your current setup.