Datadog vs New Relic (2026): LLM Observability Compared — and Where Kosmoy Fits

Three shapes on the same ten axes. Datadog (orange) and New Relic (violet) both peak on Observability & FinOps — end-to-end LLM tracing with token-cost tracking. From there they diverge sharply: Datadog reaches much further on Security, Guardrails, Testing & Evals and Agent Containment thanks to AI Guard and its eval suite, while New Relic stays closer to pure monitoring. Both sit low on Gateway, Compliance evidence and — notably — Deployment Sovereignty (SaaS-only). Kosmoy (blue) scores below Datadog on observability and evals but carries a real gateway, kernel-enforced containment and compliance evidence. Read it as area: the two APM tools own telemetry; the suite governs and contains.

Runtime AI security. AI Guard provides inline prompt-injection, tool-misuse and exfiltration blocking — genuine runtime protection New Relic does not match, since its drop filters redact telemetry rather than block the app's live traffic.

Evaluations and agentic depth. LLM Experiments, built-in and custom evaluators, datasets and human review, plus an AI Agents Console tracking third-party coding-agent usage and spend — a deeper AI feature set than New Relic's monitoring-first product.

Full-stack correlation. LLM and agent telemetry sits alongside APM, infrastructure, RUM and security signals in one platform, so an AI incident is traceable through the whole stack.

Entry cost and predictability. A 100 GB/month free ingest applies to AI monitoring data, and consumption pricing is simpler for existing New Relic shops; Datadog's LLM Observability is billed per LLM span with opaque, third-party-reported rates and a May 2026 repricing.

Openness. OpenTelemetry/OpenLIT ingestion and a free, open-source AI Coding Observability tool give New Relic a more open, portable instrumentation story.

Public-sector reach. A FedRAMP-authorized platform offering suits US-government workloads, where Datadog's Agent Observability is unavailable on the US-FED site.

Datadog and New Relic tell you what your AI did — traces, token costs, quality signals — and Datadog's AI Guard goes further, blocking some attacks inline. That telemetry is valuable, and on tracing and evals both go deeper than Kosmoy does. But observability sits beside the request path, not on it. New Relic monitors and does not enforce; Datadog's AI Guard is SDK-inline blocking, not a gateway with model routing, RBAC and budgets, and neither runs an agent inside a sandbox it cannot escape.

Kosmoy is a control plane, not a tracing tool. Its OpenAI-compatible gateway is the enforcement point — routing, RBAC, budgets and guardrails on every call — and it monitors that governed traffic for usage, cost and quality. Around it sit the layers an observability platform leaves out: an org-wide inventory with a master agent registry, kernel-enforced Action Capsule containment, and EU AI Act / ISO 42001 (aligned) / NIST AI RMF evidence — self-hosted, unlike either SaaS-only platform.

So the honest framing is not 'Kosmoy out-traces Datadog or New Relic' — for deep LLM tracing, evals and full-stack correlation they are the specialists, and Kosmoy's observability is deliberately scoped to the traffic it governs. It is that observability is one spoke. If the requirement is to govern, enforce and contain AI as one self-hosted platform — as Kosmoy does for Banca d'Italia (Italy's central bank and banking regulator) and Leonardo (Europe's largest defence and aerospace group) — that is a control-plane decision, not an observability decision.

For a team whose problem is genuinely LLM and agent observability, pick on incumbent and depth: Datadog for the deepest AI feature set — evals, AI Guard, full-stack correlation — especially if you already run Datadog; New Relic for a lighter, more open, cost-predictable fold-in for existing New Relic APM shops. Both are strong, and either can run alongside Kosmoy.

For an enterprise that must govern, enforce and contain AI — not just observe it — the decision is between an observability platform and a control plane. Many teams do both: Datadog or New Relic for deep tracing and evals, and Kosmoy as the gateway, containment and compliance layer that governs the traffic on infrastructure they own. Kosmoy can emit telemetry to either.