Buyer's guide · 2026Published July 16, 2026· Last verified July 16, 2026

Best AI Observability Platforms in 2026: 10 Compared

Ten platforms for tracing, evaluating and debugging LLM and agent behavior — scored on trace depth and evaluation rigor, not cost tracking. Organized by buyer type, with an honest note on where Kosmoy is the wrong tool.

AI observability in 2026 is really three jobs: tracing what an agent did step by step, evaluating whether the output was any good, and debugging the failures that surface in production. This guide compares ten platforms on those three — trace depth, evaluation rigor, and the debugging loop — and deliberately leaves out the fourth job, cost control, which is now a separate discipline with its own tools. If your question is 'what did we spend and how do we stop it', see Best AI FinOps Platforms in 2026; the original combined guide is Best LLM Observability & AI FinOps Platforms in 2026.

The category consolidated hard this year — ClickHouse acquired Langfuse, CoreWeave absorbed Weights & Biases, Mintlify took Helicone into maintenance mode, Palo Alto Networks bought Portkey — so ownership now matters as much as features. This guide compares by buyer situation rather than a fake 1-to-N ranking, cites every claim to the vendor's own material, and states one thing up front: Kosmoy publishes this page, it is scored last on the axes this category exists to serve, and it wins none of the pure observability buyer segments. It is on the list because it observes a slice nobody else does — governed production traffic — not because it out-traces the specialists.


What counts as AI observability platforms in 2026

What counts as AI observability in 2026? At minimum: tracing of LLM and agent activity (prompts, tool calls, retrieval steps, multi-turn sessions) with framework coverage and OpenTelemetry support; evaluation tooling (datasets, LLM-as-judge and code evaluators, human annotation, online evaluation of production); and the debugging affordances that turn a failed run into a fix. On this page we score trace depth and evaluation rigor above everything else, and we explicitly do not credit cost dashboards — that capability moved to the FinOps guide.

The market splits by architecture. SDK-instrumented platforms (LangSmith, Langfuse, Arize, W&B Weave, Braintrust, Opik, Datadog, New Relic, Helicone) watch from beside the application: rich traces, deep evals, no enforcement. A data-path platform (Kosmoy here) sits in front of the model and observes what actually transited a governed gateway — a narrower but different vantage point, useful for governance rather than for debugging a prompt. Both APM giants reframed the category this year: Datadog increasingly presents its product as agent observability, and New Relic began rebranding AI Monitoring toward 'AI Observability' in June 2026 — a signal that agents, not chat apps, now set the requirements.

Adjacent tools worth knowing but not profiled here: MLflow's Apache-2.0 tracing and evaluation, and Galileo's evaluation platform. Both are credible; we capped the roster at ten and favored platforms with the widest enterprise adoption.

How we scored the field

Every product is scored 0–10 on the same ten capability axes. A 10 is reserved for categorical architectural facts; specialists are expected to outscore platforms on their own spoke, and the scores show it.

Observability & FinOps

Trace depth and framework coverage, OpenTelemetry support, agent-first semantics (sessions, turns, tool calls), dashboards, monitors and alerts on production traffic.

Testing, Evals & Red-teaming

Datasets and experiments, LLM-as-judge and code evaluators, human annotation, online evaluation of production, CI/CD integration and red-teaming where documented — the axis that most separates this field.

Guardrails & Runtime Safety

Runtime detection and blocking of PII, toxicity and prompt injection — scored lower when enforcement must be wired per-application in code, since most observability tools only watch.

Compliance & Audit

Certifications, audit logs and retention controls; top scores reserved for AI-regulation evidence tooling (EU AI Act, ISO/IEC 42001, NIST AI RMF), which most of this category does not attempt.

Deployment Sovereignty

Self-hosting terms and license gates, VPC and dedicated options, air-gap feasibility, and whether a vendor control plane remains in the loop.


The field, scored

AI observability platforms — capability scores, 0–10
Capability (0–10)LangSmith (LangChain)LangfuseArize AIDatadog LLM ObservabilityWeights & Biases WeaveNew Relic AI MonitoringHeliconeOpik (Comet)BraintrustKosmoy
AI Inventory & Discovery2014131219
Security & Shadow AI3137223218
Observability & FinOps9999888887
Gateway & Policy Control5013106138
Guardrails & Runtime Safety4167512518
Agent Containment7013100009
Compliance & Audit4333333239
Testing, Evals & Red-teaming9896825894
Agent Building9124131216
Deployment Sovereignty99827268710

Bold marks the highest score on each row. 10 is reserved for categorical architectural facts; specialists are expected to outscore platforms on their own spoke.

Capability shape, vendor by vendor

Each panel shows one vendor across the same ten axes. Read it as area: a specialist climbs on its own spoke and falls away on the rest; a platform holds the frontier. The dashed outline is Kosmoy for reference.

LangSmith (LangChain)
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Langfuse
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Arize AI
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Datadog LLM Observability
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Weights & Biases Weave
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New Relic AI Monitoring
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Helicone
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Opik (Comet)
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Braintrust
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Kosmoy
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dashed = KosmoyINV AI Inventory & Discovery · SEC Security & Shadow AI · OBS Observability & FinOps · GW Gateway & Policy Control · GRD Guardrails & Runtime Safety · CTN Agent Containment · CMP Compliance & Audit · EVL Testing, Evals & Red-teaming · BLD Agent Building · SOV Deployment Sovereignty

The vendors, by buyer type

No single 1-to-N ranking survives contact with a real shortlist — the right pick depends on who is buying. Each vendor below is labeled with the buyer it fits best.

LangSmith (LangChain)

LLM observability, evals & agent engineering platform

Best for evals-first teams (and the broadest platform)

LangSmith is LangChain's commercial platform for agent engineering — tracing, evaluation, prompt management, agent deployment, sandboxes and a no-code agent builder, plus an LLM gateway in private beta — layered on the MIT-licensed LangChain and LangGraph frameworks.

LangSmith is the category's reference point: framework-agnostic tracing with native OpenTelemetry ingestion and an evaluation suite — datasets with splits, pairwise experiments, multi-turn evaluators, annotation queues — that no rival fully matches. Its 2026 releases (Deployment, Fleet, Sandboxes GA, Engine, an LLM gateway in private beta) make it an agent-engineering platform rather than a tool (Interrupt 2026).

The caveats are procurement-shaped: the platform is proprietary, self-hosting is Enterprise-gated with license-beacon egress outside air-gapped licenses, and there is no AI-regulation compliance tooling documented as of July 15, 2026.

Strengths

  • The deepest ecosystem gravity in the category: LangChain (~141.8k stars) and LangGraph (~37.3k stars) are MIT frameworks feeding the commercial platform, backed by a $125M Series B at a $1.25B valuation (October 2025).
  • Category-leading evaluation tooling: datasets with splits, experiments and pairwise comparison, LLM-as-judge, code and composite evaluators, online and multi-turn thread evaluators, and annotation queues with rubrics (evaluation docs).
  • Framework-agnostic observability with native OpenTelemetry ingestion, automatic token/cost tracking with per-model pricing, dashboards and alerts (observability docs).

Limits

  • The LLM Gateway is private beta (waitlist) with a narrow policy surface — spend limits plus PII/secrets redaction across 7 providers; no routing, failover or fine-grained content policies documented as of July 15, 2026.
  • No org-wide AI inventory or shadow-AI discovery — visibility covers applications instrumented with LangSmith or routed through its gateway.
  • No EU AI Act, ISO/IEC 42001 or NIST AI RMF governance tooling documented as of July 15, 2026; the compliance story is security certifications (SOC 2 Type II, ISO 27001, HIPAA, GDPR) plus audit logs.
Deployment: SaaS (US, EU, APAC regions), hybrid, or self-hosted Kubernetes (Enterprise add-on)Open source: Platform proprietary; SDKs and the LangChain/LangGraph frameworks are MITPricing: Free Developer tier; Plus at $39/seat/mo plus per-trace usage; Enterprise by quote (gates self-hosting)

Langfuse

Open-source LLM engineering platform (tracing, evals, prompts)

Best open-source self-hosted observability

Langfuse is an open-source (MIT-core) LLM engineering platform for tracing, evaluation and prompt management, self-hostable or on Langfuse Cloud, acquired by ClickHouse in January 2026 with public commitments to keep the license, roadmap and self-hosting unchanged.

Langfuse pairs an MIT core (~31k GitHub stars) with the rare promise that the self-hosted build is the exact same codebase as its cloud, unlimited and documented to run without internet access. Evals cover judges, code evaluators, Experiments with CI/CD gates and annotation queues; Monitors & Alerts arrived in June 2026. ClickHouse acquired the company in January 2026 with public continuity commitments (announcement).

Know the open-core boundary: audit logs, retention policies and project RBAC need an Enterprise key when self-hosting, and EE telemetry cannot be disabled. It observes; it never enforces.

Strengths

  • One of the most widely adopted open-source LLM engineering platforms: MIT core with ~31.2k GitHub stars and daily active development as of July 2026.
  • Self-hosting without asterisks on the core: the self-hosted build runs the exact same codebase as Langfuse Cloud with all core features and APIs unlimited, and the networking docs state it does not require internet access.
  • Deep evaluation tooling: LLM-as-a-judge, code evaluators, datasets, first-class Experiments with CI/CD quality gates in GitHub Actions (May 2026), and human annotation queues (changelog).

Limits

  • Observe-only: no gateway, runtime policy enforcement or guardrail blocking — Langfuse's own docs delegate runtime security to third-party libraries and position the product as ex-post evaluation.
  • No org-wide AI inventory, shadow-AI discovery or agent containment documented as of July 15, 2026.
  • Key governance features are Enterprise-licensed when self-hosting (audit logs, retention policies, project-level RBAC, SCIM, server-side masking), and EE license telemetry cannot be disabled.
Deployment: Langfuse Cloud (EU-default, US, Japan, HIPAA regions) or self-hosted — Docker/Kubernetes, documented to run without internet accessOpen source: MIT (core); EE features under a commercial licensePricing: OSS self-host free (MIT core, unlimited); Cloud from a free Hobby tier through Core $29/mo, Pro $199/mo and Enterprise $2,499/mo; self-hosted EE by quote

Arize AI

AI observability & evaluation platform (Arize AX + Phoenix OSS)

Best for enterprise eval rigor with an OSS on-ramp

Arize AI pairs the enterprise Arize AX platform (agent observability, evaluation and runtime guards, SaaS or self-hosted) with Phoenix, one of the most active open-source AI observability projects.

Arize AX treats evaluation as a governed discipline — the Evaluator Hub versions LLM-as-a-judge evaluators at commit level — and adds Signal continuous trace review, voice-agent replay and runtime Guards that can block or regenerate responses. Phoenix (ELv2, ~10.6k stars) is the open-source on-ramp, and AX Enterprise self-hosts Kubernetes-first, unusual among SaaS observability peers.

Gaps: no gateway, no org-wide inventory, no AI-regulation compliance tooling, and Phoenix's Elastic License is not OSI-approved open source.

Strengths

  • Dual offering few rivals match: enterprise Arize AX plus the open-source Phoenix project (ELv2, ~10.6k stars, 749 releases), still shipping weekly as of July 2026.
  • Deep evaluation stack: an Evaluator Hub with commit-level versioning of LLM-as-a-judge evaluators, datasets and experiments, and online evals on production traffic (Observe 2026 launches).
  • Documented runtime Guards — embedding-based and RAG LLM guards on inputs and outputs with block, default-response or regeneration actions (guardrails docs) — rare among observability specialists.

Limits

  • No org-wide AI inventory or shadow-AI discovery documented as of July 15, 2026 — projects and spaces exist only inside the platform.
  • No LLM gateway or central runtime policy point: guards intercept calls at SDK level inside the application, not at a traffic chokepoint with routing and RBAC.
  • No agent containment — sandboxing, kill switch or scoped credentials are not documented as of July 15, 2026.
Deployment: AX Free/Pro are SaaS; AX Enterprise as SaaS or self-hosted (Kubernetes-first, major clouds and private VPC); Phoenix OSS runs anywhereOpen source: Phoenix under Elastic License 2.0; Arize AX platform proprietaryPricing: AX Free tier; AX Pro at $50/mo; AX Enterprise by quote (SaaS or self-hosted); Phoenix OSS free

Datadog LLM Observability

LLM/agent observability within a general-purpose APM platform

Best for teams already on Datadog

Datadog LLM Observability — increasingly framed by Datadog as agent observability — adds LLM/agent tracing, token-cost tracking and evaluations to the Datadog platform, with AI Guard supplying runtime AI security.

If Datadog already runs your monitoring, its LLM Observability is the lowest-friction answer here: LLM and agent traces correlated with APM, infrastructure and RUM, LLM Experiments for evals, and — uniquely among the SDK-instrumented family — AI Guard blocking prompt injection, tool misuse and data exfiltration at runtime. The AI Agents Console (Preview) tracks agent activity across the organization.

It is SaaS-only — telemetry must flow to Datadog — its evaluation suite is lighter than the eval specialists', and standalone list pricing is opaque as of July 15, 2026.

Strengths

  • LLM and agent telemetry correlated with full-stack APM, infrastructure, RUM and security data in one platform (product page) — a correlation story no observability specialist can match.
  • AI Guard adds genuine runtime blocking — prompt-injection and jailbreak protection, tool-call protection and sensitive-data exfiltration prevention — rare among observability vendors (AI Guard docs).
  • The AI Agents Console (Preview) tracks org-wide usage, spend and impact of third-party coding agents such as Claude Code, Cursor and GitHub Copilot (docs).

Limits

  • No self-hosted or customer-VPC deployment: telemetry must flow to Datadog's SaaS, which rules it out for strict sovereignty or air-gapped requirements.
  • No org-wide AI system registry or shadow-AI discovery beyond coding-agent usage monitoring, and the AI Agents Console is still in Preview as of July 15, 2026.
  • Standalone LLM Observability list pricing is opaque: the official page publishes no per-span rates, and third-party sources report conflicting figures and a May 2026 repricing.
Deployment: Multi-tenant SaaS across Datadog regional sites (US, EU); no self-hosted control planeOpen source: ProprietaryPricing: Free tier of 40K LLM spans/month; paid usage billed per LLM span; enterprise via Datadog contract — official per-span list rates not published

Weights & Biases Weave

LLM/agent tracing & evaluation within the W&B platform

Best for ML platform teams on W&B

W&B Weave is Weights & Biases' toolkit for tracing, evaluating and monitoring LLM and agent applications — agent-first trace semantics on top of the W&B ML platform, owned by CoreWeave since May 2025.

W&B Weave extends the experiment-tracking platform ML teams already trust into LLM territory, with agent-first trace semantics (sessions, turns, steps, tools), datasets-plus-scorers evaluation, inline safety scorers and Online Evaluations for production agents. For organizations training models and shipping agents, one platform covering both is a real consolidation.

Weave observes rather than enforces, guardrails are wired per-application in code, and CoreWeave's ownership (May 2025) orients the roadmap toward its AI cloud — self-managed parity and air gap remain undocumented as of July 15, 2026.

Strengths

  • An agent-first trace model — sessions, turns, steps, tools and sub-agents as first-class concepts — rather than generic code tracing (Weave production-agent announcement).
  • Evaluation lineage from the W&B experiment-tracking platform widely used in ML research: datasets plus scorers, side-by-side comparisons and human feedback (evaluations page).
  • Pre-built safety and quality scorers — toxicity, bias, PII, hallucination, prompt injection — usable inline as guardrails (guardrails docs).

Limits

  • Owned by CoreWeave since May 2025: the roadmap increasingly orients toward CoreWeave's AI cloud (W&B Inference, Mission Control), a consideration for buyers standardized on other clouds.
  • Guardrail enforcement is developer-wired in application code via the SDK — there is no central policy point independent of each application.
  • No org-wide AI inventory, gateway or shadow-AI discovery documented as of July 15, 2026.
Deployment: Multi-tenant SaaS (Free/Pro); Enterprise offers Dedicated Cloud or customer-managed self-hosted deploymentOpen source: Weave SDK Apache-2.0; W&B platform proprietaryPricing: Free tier; Pro with usage-based Weave data ingestion; Enterprise custom (dedicated or customer-managed)

New Relic AI Monitoring

APM-integrated AI/LLM monitoring platform

Best for New Relic APM estates

New Relic AI Monitoring — rebranding toward AI Observability during 2026 — extends New Relic's APM agents to trace LLM calls and AI agents, with token/cost tracking, response-quality feedback and model comparison inside the New Relic platform.

New Relic mirrors Datadog's logic one estate over: LLM traces through the APM agents you already deploy, model comparison, multi-agent visualization in preview, and a 2026 roadmap (SRE Agent, an Agentic Platform with MCP support, the June 2026 shift toward 'AI Observability' branding) that keeps pace. The free ingest allowance makes trying it effectively free for existing customers.

It is the thinnest on evaluation in this guide — no datasets, experiments or judge evaluators documented as of July 15, 2026 — SaaS-only, and its agentic features remain largely in preview.

Strengths

  • AI telemetry lands in the same platform as APM, infrastructure and logs — zero extra vendors for existing New Relic estates (AI monitoring docs).
  • Instrumentation reuses existing APM language agents, plus OpenTelemetry and OpenLIT ingestion paths for LLM telemetry.
  • A visible 2026 agentic roadmap: SRE Agent, AI Agent Monitoring in preview for multi-agent systems, and a no-code Agentic Platform with MCP support, announced February 2026 (TechCrunch).

Limits

  • No evaluation framework — datasets, experiments, LLM-as-judge — or red-teaming documented as of July 15, 2026; thin next to eval-first competitors.
  • No runtime guardrails or gateway: monitoring only, and drop filters affect telemetry rather than the application's LLM traffic.
  • SaaS-only — no self-hosted or customer-VPC deployment documented as of July 15, 2026.
Deployment: Multi-tenant SaaS (US/EU data centers; FedRAMP-authorized offering at platform level); no self-hosted optionOpen source: Platform proprietary; APM agents and the AI Coding Observability tool (June 2026) are open sourcePricing: Consumption pricing: free monthly data-ingest allowance, then per-GB ingest plus per-user fees; AI Monitoring is part of platform ingest rather than a separate SKU

Helicone

LLM observability platform with an AI gateway

Continuity only — in maintenance mode

Helicone is an open-source, developer-first LLM observability platform (traces, costs, prompts, experiments) with a lightweight Rust AI gateway and zero-markup cloud gateway — in maintenance mode since Mintlify acquired the company in March 2026, with feature development ended.

Helicone is a capable open-source (Apache-2.0) LLM observability platform: one-line integration, agent trace debugging, sessions, alerts and an HQL query language, with prompt-iteration tooling — experiments, scoring, fine-tuning datasets — on top (repo). For teams already running it, it still does the job.

The caveat governs the recommendation: it has been in maintenance mode since the March 2026 Mintlify acquisition — security patches and new-model support continue, but feature development has ended (announcement). Fine for existing users; a material risk for new adoption. Plan a migration path to Langfuse or Opik on your own schedule.

Strengths

  • Mature open-source LLM observability (Apache-2.0, YC W23) with one-line integration, agent trace debugging, sessions, alerts and deep cost analytics (Helicone repo).
  • A dual gateway track: a lightweight self-hostable Rust gateway (vendor claims P95 under 5ms in ~64MB of memory) and a cloud gateway fronting 100+ models (ai-gateway repo).
  • Zero-markup passthrough billing with automatic fallback to bring-your-own-keys — an unusually developer-friendly gateway pricing model.

Limits

  • In maintenance mode since the March 2026 Mintlify acquisition — feature development has ended (Helicone announcement, Mintlify announcement). Workable for existing users; a material risk for new adoption.
  • No native guardrails — PII redaction, toxicity or prompt-injection blocking are not documented as of July 15, 2026.
  • No AI inventory, enterprise governance layer or compliance-framework tooling (EU AI Act, ISO 42001, NIST AI RMF not documented).
Deployment: SaaS; full platform self-hostable (Docker Compose, Helm); no air-gapped option documentedOpen source: Apache-2.0 (main platform repo, ~5.9k stars)Pricing: Free Hobby tier (10k requests/month); Pro from $79/mo; Team $799/mo adds SOC 2 and HIPAA; gateway usage billed at provider cost (zero markup).

Opik (Comet)

Open-source LLM evaluation & observability platform

Best budget open-source option

Opik is Comet's Apache-2.0 open-source platform for tracing, evaluating, monitoring and optimizing LLM applications and agents — self-hosted with no feature restrictions, or as Comet-managed cloud.

Opik is the value pick: Apache-2.0 with ~20.6k stars, unlimited spans and no feature restrictions when self-hosted, plus judges, datasets, online evaluation rules, an Agent Optimizer and beta guardrails (PII filtering, topic moderation) in one toolkit. The managed Pro tier undercuts nearly every commercial rival.

Guardrails remain beta with no prompt-injection blocking documented as of July 15, 2026, and Comet's funding is modest against the category's 2025-26 raises.

Strengths

  • One of the largest open-source LLM-eval projects: Apache-2.0, ~20.6k stars, 524 releases with daily-cadence development as of July 2026.
  • Self-hosted OSS carries unlimited spans and no feature restrictions — a genuinely low-cost sovereign option (Opik FAQ).
  • Evals, tracing, guardrails and agent optimization in a single toolkit: LLM-as-a-judge metrics, datasets and experiments, online evaluation rules, and the Opik Agent Optimizer.

Limits

  • No org-wide AI inventory, gateway or shadow-AI discovery documented as of July 15, 2026.
  • Guardrails are still in beta and cover PII and topic moderation only — no prompt-injection blocking documented as of July 15, 2026.
  • No agent containment or AI compliance-framework tooling documented as of July 15, 2026.
Deployment: Self-hosted OSS (Docker Compose or Kubernetes) with no feature restrictions, or Comet-managed cloud; Enterprise offers custom hostingOpen source: Apache-2.0Pricing: OSS self-host free with unlimited spans; managed cloud Free tier, Pro at $39/mo with unlimited team members, Enterprise by quote

Braintrust

Evals-first LLM engineering & observability platform

Best for product teams where evals are the dev loop

Braintrust is an evaluation-centric platform for building AI products — eval suites, production trace logging on the purpose-built Brainstore, playgrounds and the Loop AI assistant — with a hybrid self-hosted data plane for enterprises.

Braintrust builds everything around the eval: an Eval() SDK, autoevals, human review, Brainstore for querying million-token agent traces, Topics for clustering production failure patterns, and Loop turning those failures into new datasets and scorers from natural language. An $80M Series B (February 2026) signals staying power, and the Enterprise hybrid keeps all trace data in your VPC.

The control plane always runs at Braintrust — no full self-host or air gap — and there are no guardrails, inventory or AI-regulation compliance tooling; scorers observe rather than block.

Strengths

  • A deep evals-first workflow — Eval() SDK, autoevals, LLM-as-a-judge and code scorers, datasets, experiments and human review — adopted widely among AI-native product teams (Series B blog).
  • Brainstore, a store purpose-built for querying millions of large nested agent traces, with online scoring and Topics pattern clustering across production runs (June 2026).
  • A hybrid architecture that keeps all trace, eval and dataset content in the customer's environment while retaining a managed UI (architecture docs).

Limits

  • No runtime guardrails or policy gateway: the AI Proxy unifies access but does not enforce safety or policy on traffic, and scorers run asynchronously rather than blocking.
  • No org-wide AI inventory, shadow-AI discovery or compliance-framework tooling documented as of July 15, 2026.
  • Self-hosting is data-plane only and gated to Enterprise; the control plane always runs at Braintrust, so there is no full on-prem or air-gapped deployment.
Deployment: SaaS by default; Enterprise hybrid self-hosts the data plane (Terraform/AWS, Docker, Helm) while Braintrust hosts the control planeOpen source: Core platform proprietary; AI Proxy (MIT) and SDKs/autoevals open sourcePricing: Free Starter tier; Pro subscription; Enterprise by quote (self-hosted data plane, custom RBAC, BAA) — billed on processed data and scores rather than spans

Kosmoy

AI management platform

Not an observability specialist — a control plane that observes

A self-hosted control plane for enterprise AI: one inventory, one policy gateway, one audit trail and a containment sandbox for every model, agent and MCP server a company runs.

Kosmoy is last on this list by design, and the honest framing matters: it is not a tracing or evaluation tool. Its evals score is a 4 — there is no dataset, LLM-as-judge or experiment tooling at all — and any of the nine platforms above will out-trace and out-evaluate it. What it does is observe governed production traffic: usage, latency, cost and quality across every call that transits its gateway, with real-time guardrail-violation alerts and per-team, per-app attribution in the Insights Dashboard.

Pick Kosmoy only when the problem is governance, not debugging — when you need an org-wide AI inventory, in-path guardrails, agent containment and audit evidence, and want operational monitoring as one layer of that control plane rather than a standalone eval suite. The common pattern is an eval specialist for builders plus Kosmoy as the governed control plane; it runs single-tenant in your own Kubernetes, air-gapped if needed.

Strengths

  • Four registries — AI systems, models, MCP servers and a master agent registry that pulls agents from Azure AI Foundry, Bedrock, Vertex, Salesforce and ServiceNow into one list.
  • One OpenAI-compatible gateway enforcing guardrails, RBAC, budgets and logging on every LLM, MCP and A2A call.
  • Action Capsule: kernel-enforced sandboxing for agents, MCP servers and private models, with per-task credentials and a kill switch.

Limits

  • No dedicated evaluation or red-teaming suite — teams pair Kosmoy with a specialist evals tool.
  • The agent builder covers governed internal use cases; dedicated agent-development platforms go deeper.
  • No free or self-service tier — procurement runs through an enterprise sales process.
Deployment: Self-hosted — single-tenant, your own Kubernetes (air-gap capable)Open source: ProprietaryPricing: Enterprise subscription; no self-service tier.

Questions buyers ask

What is the best AI observability platform in 2026?

There is no single answer, which is why this guide is organized by buyer type. For an AI engineering team building its evaluation discipline, LangSmith is the most complete platform, with Braintrust and Arize close behind on eval depth. For an enterprise already on Datadog or New Relic, extending the APM estate usually beats adding a vendor. For OSS self-hosters, Langfuse, or Opik on a budget. The 'best' tool is the one whose architecture matches where you need visibility.

Does Kosmoy replace LangSmith or Langfuse?

No — and this guide says so plainly. Kosmoy has no evaluation suite: no datasets, no LLM-as-judge, no experiments, and its tracing is operational monitoring of governed traffic rather than deep step-level debugging. Teams that need those tools should buy them. Kosmoy replaces the layer none of the eval tools provide: an org-wide [AI inventory](/platform/ai-inventory/), a self-hosted gateway that enforces guardrails and budgets, agent containment, and audit evidence for EU AI Act, ISO/IEC 42001 (aligned) and NIST AI RMF. The common pattern is one eval tool for builders plus Kosmoy as the control plane.

What happened to Helicone?

Mintlify acquired Helicone in March 2026 and the product entered maintenance mode: security patches, bug fixes and new-model support continue, but feature development ended. Existing deployments keep working and the open-source core remains available. We kept it on the roster because many teams still run it, but flagged it as a continuity choice rather than a fresh-adoption one; current users should plan a migration path to Langfuse or Opik on their own schedule.

Are open-source AI observability tools good enough for production?

Yes, for the observability job itself. Langfuse (MIT core) and Opik (Apache-2.0) run large production workloads self-hosted, with real evaluation tooling and active development — Langfuse now with ClickHouse's backing. The honest limits: enterprise governance features often sit behind commercial licenses (Langfuse's EE tier), certifications vary, and none of the OSS tools provides runtime enforcement or AI-regulation compliance evidence. Good enough for engineering; not sufficient, alone, for a regulator.

Where did the cost-tracking comparison go?

This guide used to cover AI FinOps too. In 2026 cost control became a distinct discipline with its own buyers and tools, so we split it out: token attribution, budgets, chargeback and optimization are now in [Best AI FinOps Platforms in 2026](/resources/blog/best-ai-finops-platforms-2026/). Several platforms appear on both pages — Datadog and Portkey especially — because they do both jobs, but the enforcement and unit-economics story lives in the FinOps guide.


Methodology

Every vendor was scored on the same ten capability axes used across Kosmoy's comparison pages, from primary sources — vendor documentation, pricing pages, engineering blogs and repositories — checked on July 15, 2026 and cited inline or in each vendor's profile. On this page we weight the tracing and evaluation axes above the rest. Scores of 10 are reserved for categorical architectural facts; a specialist always outscores Kosmoy on its own spoke, which is why every other platform here beats Kosmoy on observability and evals.

Numbers from vendors appear as attributed claims with citations, never as our measurements. Gaps are phrased 'does not document X as of July 15, 2026', a claim about documentation rather than proof a capability cannot exist. Ownership changes that bear on a recommendation — ClickHouse/Langfuse, CoreWeave/W&B, Mintlify/Helicone, Palo Alto Networks/Portkey — are flagged wherever they matter, and Helicone's maintenance-mode status is stated at every mention.

Disclosure: Kosmoy publishes this guide. The mitigation is structural — Kosmoy is ranked last, wins none of the four buyer picks, and the rubric concedes plainly that it is not a tracing or eval platform. The recommendations name a specialist for every buyer type this category actually serves.

Sources

Every factual claim about another vendor on this page traces to that vendor's own published material or a named third-party source below.

  1. Interrupt 2026 launches (LangChain blog) — accessed July 15, 2026
  2. Langfuse joins ClickHouse (January 2026) — accessed July 15, 2026
  3. Mintlify acquires Helicone (March 3, 2026) — accessed July 15, 2026
  4. CoreWeave completes acquisition of Weights & Biases (May 2025) — accessed July 15, 2026
  5. Datadog AI Guard docs — accessed July 15, 2026
  6. Helicone main GitHub repo — accessed July 15, 2026
  7. Kosmoy AI Monitoring — Insights Dashboard — accessed July 15, 2026
  8. LangSmith self-hosted overview (docs) — accessed July 15, 2026
  9. LangSmith self-hosted egress & air-gapped licensing (docs) — accessed July 15, 2026
  10. LangSmith LLM Gateway (docs, private beta) — accessed July 15, 2026
  11. LangSmith Sandboxes (docs) — accessed July 15, 2026
  12. LangSmith Fleet overview (docs) — accessed July 15, 2026
  13. LangSmith Deployment overview (docs) — accessed July 15, 2026
  14. LangSmith pricing — accessed July 15, 2026
  15. Fortune — LangChain raises $125M at $1.25B valuation — accessed July 15, 2026
  16. Langfuse GitHub repository (MIT core, stars) — accessed July 15, 2026
  17. Self-hosting overview (same codebase as Cloud) — accessed July 15, 2026
  18. Enterprise license key (EE feature list, MIT core unlimited) — accessed July 15, 2026
  19. Networking (no internet access required) — accessed July 15, 2026
  20. Telemetry (EE license telemetry cannot be disabled) — accessed July 15, 2026
  21. Security & guardrails doc (runtime blocking delegated to third parties) — accessed July 15, 2026
  22. Langfuse pricing — accessed July 15, 2026
  23. Changelog (Experiments, CI/CD gates, Monitors & Alerts) — accessed July 15, 2026
  24. Phoenix GitHub repository — accessed July 15, 2026
  25. Arize AX self-hosting docs — accessed July 15, 2026
  26. Arize AX guardrails docs — accessed July 15, 2026
  27. Observe 2026 / Arize AX launches (blog) — accessed July 15, 2026
  28. Arize AX release notes — accessed July 15, 2026
  29. Arize pricing — accessed July 15, 2026
  30. Series C press release ($70M) — accessed July 15, 2026
  31. Datadog LLM Observability product page — accessed July 15, 2026
  32. AI Agents Console docs — accessed July 15, 2026
  33. Datadog press release — agentic AI monitoring, LLM Experiments, AI Agents Console — accessed July 15, 2026
  34. Datadog LLM Observability pricing — accessed July 15, 2026
  35. AI Guard launch blog — accessed July 15, 2026
  36. Weave GitHub repository (Apache-2.0 SDK) — accessed July 15, 2026
  37. W&B pricing — accessed July 15, 2026
  38. Weave guardrails and monitors docs — accessed July 15, 2026
  39. CoreWeave + W&B new products press release — accessed July 15, 2026
  40. Weave production-agent observability announcement — accessed July 15, 2026
  41. Intro to AI monitoring (docs) — accessed July 15, 2026
  42. AI agent monitoring (docs) — accessed July 15, 2026
  43. TechCrunch — New Relic agent platform and OpenTelemetry tools (Feb 2026) — accessed July 15, 2026
  44. AI Coding Observability coverage (June 2026) — accessed July 15, 2026
  45. New Relic pricing — accessed July 15, 2026
  46. Helicone AI Gateway repo (Rust) — accessed July 15, 2026
  47. Helicone pricing — accessed July 15, 2026
  48. Mintlify acquires Helicone (March 2026) — accessed July 15, 2026
  49. Helicone cloud gateway / passthrough billing launch — accessed July 15, 2026
  50. Opik GitHub repository (Apache-2.0) — accessed July 15, 2026
  51. Opik FAQ (deployment, no feature restrictions) — accessed July 15, 2026
  52. Comet pricing — accessed July 15, 2026
  53. Opik Guardrails beta announcement — accessed July 15, 2026
  54. Comet company profile (funding) — accessed July 15, 2026
  55. Braintrust Series B announcement — accessed July 15, 2026
  56. Platform architecture docs (hybrid data plane) — accessed July 15, 2026
  57. Plans and limits — accessed July 15, 2026
  58. AI Proxy repository (MIT) — accessed July 15, 2026
  59. SiliconANGLE — Braintrust $80M Series B (Feb 2026) — accessed July 15, 2026
  60. Braintrust pricing — accessed July 15, 2026
  61. Kosmoy Platform — accessed July 15, 2026
  62. Kosmoy AI Gateway — accessed July 15, 2026
  63. Kosmoy Action Capsule — accessed July 15, 2026
  64. Kosmoy AI Compliance — accessed July 15, 2026

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