Reading Your LLM Gateway Invoice: Credits, Fees & Governance

LLM gateway invoices hide three charges: the tokens you burned, the platform fee on top, and the minimums and allowances that reshape both. Here's how to read each line, using the documented nRouter as an OpenRouter alternative comparison.

The fee line

OpenRouter: 5.5% card fee on credit purchases, $0.80 minimum. nRouter: flat 4% of credits, no minimum fee. On $5: $5.80 vs $5.20. On $100: $105.50 vs $104.00. Minimums hit small top-ups hardest; the 1.5-point swing matters past ~$1k/month.

The governance line

nRouter bundles guardrails, A/B evals, prompt management, and per-team budgets on every plan. OpenRouter's documented matrix: not offered. DIY governance is engineering time your invoice never shows.

The migration line

Base-URL and key swap:

# OpenAI-compatible switch
client = OpenAI(
    base_url="https://api.nrouter.ai/v1",
    api_key=api_key,
)

The real work is policy mapping: quotas, spend alerts, team permissions, cost attribution.

The stay line

BYOK keeps negotiated rates. The catalog tail and public discovery surface are genuine OpenRouter strengths. If either is your situation, the fee math is secondary.

Run your own numbers against the documented figures in the nRouter as an OpenRouter alternative write-up.