Helicone vs nRouter: The Request-Path Test Every LLM Gateway Evaluation Should Run

Here's a test I now run on every LLM infrastructure evaluation, and it takes about thirty seconds: can it refuse a request?

Not log it. Not chart it. Refuse it — before the provider call happens, before a token is billed.

Why this test exists

Helicone is an observability product. It offers a request-path proxy and an async logging SDK, and the async path is the one to understand: it records calls after they happen. By construction, nothing off the request path can refuse a request.

That's fine for analysis. It fails the test above. If the guardrail you want lives on the path you're not using, no plan upgrade changes physics.

nRouter is an inline gateway — every request passes through it. Preflight checks (guardrails, hierarchical budget enforcement) run before the provider call. An exhausted budget returns 402/429 before a token is billed; blocked guardrail requests cost zero credits.

from openai import OpenAI

# nRouter: OpenAI-compatible endpoint, one managed key
client = OpenAI(base_url="https://api.nrouter.ai/v1", api_key="nr-...")
chat = client.chat.completions.create(
    model="openai/gpt-4o-mini",
    messages=[{"role": "user", "content": "Summarize this thread."}],
)

The migration from Helicone's proxy is a baseURL swap: drop the provider key and the Helicone-Auth header, use one nRouter key.

The plan-ladder test

Second test: which plan are the features on?

On Helicone's published pricing (checked 2026-08-23), guardrails, custom rate limits, evals/scores, prompt management, sessions, and alerts all begin on Pro at $79/month. SOC-2 and HIPAA begin on Team at $799/month. Helicone ships these features — the difference is which plan they're on. The first time you need to block something rather than watch it, the answer is a plan change.

nRouter puts guardrails and hierarchical budgets (org → team → user → key; daily/weekly/monthly/lifetime; block/warn/throttle) on every plan, with a flat 4% platform fee on credits as the commercial lever. Entry is a $5 minimum credit purchase, card required — no free tier.

The retention test

Third: how long do the logs live? Helicone Pro: 30 days. Team: 90 days. Enterprise: unlimited. A 30-day window plus a 60-calls-per-minute export API means your quarterly cost review needs an export pipeline before the window closes. nRouter keeps a ledgered spend history — good for cost questions, thin for debugging. Neither is a warehouse; plan accordingly.

The BYOK test

Fourth: whose keys pay? Helicone supports BYOK — your provider key keeps your provider billing, so provider credits and negotiated rates stay intact — plus a 0%-markup credits path. nRouter has no BYOK: one managed key, nRouter holds the upstream credentials. Provider-granted credits and negotiated rates cannot be spent through nRouter. This is the architectural position, not a gap that closes. If your finance team negotiated provider rates, this single test decides the shortlist before any feature matrix.

When to stay on Helicone

Be honest about it. Stay on Helicone if you need session replay, HQL trace querying, datasets, BYOK economics, Google models (nRouter doesn't serve them), or certified SOC-2/HIPAA today (nRouter's SOC 2 Type II is in progress). Move to an inline gateway when your next three needs are guardrails, evals, and per-team budgets on every plan.

Every claim on both sides, traced to the vendors' own published pricing and docs, is in the full Helicone comparison.

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Originally published as part of nRouter's documented Helicone comparison.