# LLM observability and cost tracking, per request

> Markdown mirror of https://router.one/llm-observability for AI assistants and crawlers. Router One is an OpenAI-compatible LLM API gateway.

Router One is an OpenAI-compatible LLM API gateway, and every request through it produces a trace. For each call across 25+ models — GPT, Claude, Gemini, DeepSeek, Mistral, Llama — you see the model, provider, input/output tokens, cost at the posted rate, latency, status code, and the exact route or fallback path the request took. It is request-level visibility and spend control for developers and small teams, not an enterprise audit, compliance, or RBAC system.

## What you get in every trace

| Signal | Router One trace | Calling the provider directly |
| --- | --- | --- |
| Model & provider used | Recorded per request, including the resolved route | Whatever your one SDK call targeted |
| Input / output tokens | Counted and stored per request | In the response, if you log it yourself |
| Cost per request | Computed at the posted model rate, no markup added | You reconcile invoices later |
| Latency | Measured end to end and stored | Only if you instrument it |
| Route / fallback decision | Trace shows the route taken and any fallback | No fallback; a 5xx is just an error |
| Status code & errors | Logged per request, searchable in Logs | In your own logs, if any |
| Spend ceiling | Per-key maxSpend stops a runaway loop | No hard ceiling on the key |

## Where to look

### Dashboard -> Logs

Every request is one row: model, provider, tokens, cost, latency, status, and the route/fallback path. Filter by API key or model to find the call that misbehaved, then open it for the full trace.

### Dashboard -> Usage

Per-model and per-API-key breakdowns of requests, tokens, and spend over time. See which model and which key are driving cost, all priced at the posted rate from your prepaid wallet.

### Budgets & rate limits

Each API key carries its own maxSpend plus rateLimit and tokenLimitTpm. A runaway loop hits its own ceiling and stops instead of draining the whole balance — spend control without a governance suite.

## What stays private

Router One does not retain prompt or completion bodies. Only metadata — model, provider, token counts, cost, latency, status, and the route/fallback path — is logged, and it is used for billing, routing, and observability. You get the numbers you need to debug and budget without your prompts being stored.

## FAQ

### What exactly is in a trace?

Each request records the model, provider, input and output token counts, cost at the posted rate, end-to-end latency, the HTTP status code, and the route or fallback path the request took. You can see it per request in Dashboard -> Logs and in aggregate in Dashboard -> Usage.

### Does Router One store my prompts and responses?

No. Router One does not retain prompt or completion bodies. Only request metadata is logged — for billing, routing, and observability. See the data retention page for the full boundary.

### How do I stop a runaway loop from draining my balance?

Give the API key a maxSpend, plus rateLimit and tokenLimitTpm. When a loop hits the key's spend ceiling or rate limit, requests on that key stop instead of consuming the whole wallet. Budgets are per key, not per project.

### Is this an enterprise audit or compliance platform?

No. This is request-level observability and spend control for developers and small teams. It is not an audit log, compliance, or RBAC system. There is no organization/role structure — limits and budgets attach to API keys.

### What does the trace show when a provider fails?

When latency spikes or error rates climb on a route, smart routing fails over to a healthy same-family route as long as one is available, and the trace records both the original route and the fallback decision so you can see exactly what happened.

## See also

- Canonical page: https://router.one/llm-observability
- Models and per-model token rates: https://router.one/models (markdown: https://router.one/models.md)
- Pricing: https://router.one/pricing
- API docs (markdown): https://router.one/docs.md
- Company facts: https://router.one/facts/company.md