Best LangSmith Alternatives in 2026: 8 LLM Observability Tools Compared

#1

Langfuse

Best for: Teams that want open-source LLM observability without lock-in

Visit langfuse.com

Langfuse is the most widely adopted open-source LLM engineering platform, and it covers the full loop LangSmith users expect: trace production behavior, manage prompts, run evals, and test improvements against real datasets. It works with any language and framework through OpenTelemetry, with 100+ integrations for faster setup, and it promises never to lock in your data.

The free tier covers 50,000 observations per month with no credit card required, which is enough for a serious prototype or a small production app. Paid pricing is not shown on the homepage, so check the pricing page for team plans. For teams that value open source and control over their data, Langfuse is the default LangSmith alternative.

#2

Braintrust

Best for: Teams that want observability, evals, and discovery together

4.3/5 on G2 (58 reviews, checked Oct 2026)

Visit braintrust.dev

Braintrust calls itself the active observability platform for agents, and the pitch is breadth: inspect every agent trace and tool call, track latency, cost, and quality in real time, then run experiments against versioned datasets and score outputs with LLMs, code, or humans. Its discovery layer applies intelligence to traces to surface patterns, diagnose failures, and verify fixes with evidence, all in one system.

Brainstore, its database built for AI data, searches long prompts, model responses, and tool calls quickly, which matters once production volume grows. Pricing is not shown on the homepage, so check current plans. For teams that want the whole team, from engineering to product, working in one observability tool, Braintrust is the strongest all-rounder here.

#3

Arize Phoenix

Best for: Self-hosted open-source observability

Visit phoenix.arize.com

Arize Phoenix is the self-hosting purist's pick. The open-source core traces, evaluates, and improves AI agents, runs locally in seconds or self-hosted in your own environment, and keeps your traces on your own infrastructure. Native OpenTelemetry support means your traces work with the tools you already use, with no proprietary lock-in, and the project carries 10,000+ GitHub stars with 3M+ monthly downloads.

The trade is that the hosted experience and enterprise features sit behind commercial plans, and the interface speaks to engineers first. For teams with strict data residency needs or a self-host-first policy, Phoenix is the cleanest LangSmith replacement.

#4

Opik

Best for: Open-source evals with automatic fix tooling

Visit comet.com

Opik, built by Comet, logs every step an agent takes, from user interactions to tool calls, with automated eval workflows to find and fix errors across development, testing, and production. Its 30+ metrics cover answer relevance, context precision, task completion, and hallucination, while production monitoring adds guardrails against policy violations and PII exposure.

The standout is Ollie, an AI debugging assistant that analyzes traces, suggests fixes, and implements them in your code with regression tests, so the same failure does not slip through twice. The core is open source with a free tier that needs no credit card. For teams that want evals that lead directly to code fixes, Opik is the most action-oriented option here.

#5

Galileo

Best for: Teams that want evals to become production guardrails

Visit galileo.ai

Galileo takes a different angle from the tracing-first tools: it starts with measurement. Its platform builds datasets from synthetic, development, and live production data, auto-tunes eval metrics from live feedback, and then turns those evals into production guardrails. The key trick is Luna, compact models distilled from expensive LLM-as-judge evaluators that monitor all traffic at low latency and 96 percent lower cost.

Deployment options cover SaaS, virtual private cloud, and on-premises, which suits enterprises with strict requirements. Pricing is not shown on the homepage, and access is trial-based. For teams whose core problem is proving AI quality before and after shipping, Galileo is the measurement-first pick.

#6

Weights and Biases Weave

Best for: Teams already using Weights and Biases

Visit wandb.ai

Weave is the LLM tracing layer inside Weights and Biases, the AI developer platform now part of CoreWeave Forge. Setup is a few lines of code: initialize Weave, decorate your functions, and every LLM call, retrieval step, and agent action is tracked. Teams already using W&B for experiments and training runs get tracing in a tool they know, with compliance covering SOC 2, HIPAA, and GDPR.

Pricing is not shown on the homepage, so check current plans, and the CoreWeave acquisition means packaging may evolve. For teams with existing W&B usage, Weave is the lowest-friction LangSmith alternative. Teams starting fresh may prefer a dedicated tool like Langfuse.

#7

SigNoz

Best for: Teams that want LLM telemetry inside full-stack observability

Visit signoz.io

SigNoz is the generalist of this list, and that is its strength. It is an open-source observability platform covering APM, logs, traces, infrastructure, alerts, and dashboards, with LLM telemetry added for agent teams. Its OpenTelemetry-native design means instrumentation stays portable, and its query builder, PromQL, and ClickHouse SQL run on a fast columnar store built for high-cardinality data.

Cloud Teams plans start at $49 per month with usage-based pricing and no host or seat charges, while self-hosting is free. The trade is that LLM evals are less deep here than in dedicated tools, and cloud costs depend on telemetry volume. For teams that want one observability home for apps and agents alike, SigNoz is the best fit.

#8

Portkey

Best for: Teams that also need an AI gateway

Visit portkey.ai

Portkey covers the production stack around observability, not just tracing. Its AI gateway gives access to 1,600+ LLMs through a unified API, with caching, routing, and fallbacks, while observability, guardrails, governance, and prompt management sit in the same platform. Integration takes three lines of code, and the platform now also carries the PRISMA AIRS AI Gateway name for enterprise governance.

Pricing is not shown on the homepage, so check current plans, and teams that only want tracing may find the gateway scope more than they need. For teams standardizing how models are accessed, governed, and observed, Portkey replaces LangSmith plus a gateway in one move.