AI observability AI tools

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LangSmith

Free

AI observability

The end-to-end platform for building, testing, and monitoring LLM-powered applications

Free tier available · Paid plans for production use

A

AgentOps

Free

AI observability

Trace, Debug, & Deploy Reliable AI Agents — the leading developer platform for AI agents and LLM apps.

Free tier up to 5,000 events; Pro at $40/month (pay as you go, unlimited events/logs, Slack & email support, RBAC); Enterprise at custom pricing (SLA, SSO, on-premise, self-hosting, SOC-2/HIPAA).

B

Braintrust

Free

AI observability

The AI observability platform for building quality AI products at scale

Starter: $0/mo (free tier, $10 model credits, 1 GB processed data, 10k scores, 14-day retention). Pro: $249/mo ($100 credits, 5 GB processed data, 50k scores, 30-day retention, RBAC, priority support). Enterprise: custom pricing with custom retention, on-prem or hosted deployment.

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Cleanlab

Free

AI observability

Keep AI mistakes away from your customers.

C

Confident AI

Free

AI observability

Where AI Quality is Standardized. Not Improvised.

Free tier ($0, 2 seats, 1 project, 5 test runs/week, 1 GB-month traces); Starter ($200/month, unlimited seats, 5 projects, 5 GB-months traces then $1/GB-month); Team ($2,000/month, unlimited seats/projects, 75 GB-months traces then $1/GB-month); Enterprise (custom pricing, unlimited everything, on-prem, HIPAA).

H

HoneyHive

Free

AI observability

Agent Observability and Evaluation Platform

Free tier includes 10,000 events/month, up to 5 users, 30-day data retention, automated & human evaluations, prompt versioning, CI/CD integration, and community support. Enterprise tier offers custom usage limits, unlimited users & workspaces, SAML & custom SSO, custom data retention, uptime SLA, custom DPA and BAA, dedicated TAM & QBRs, and optional self-hosting/hybrid/single-tenant deployment.

L

Laminar

Free

AI observability

Open-source observability platform purpose-built for AI agents

Free ($0/mo, 1 GB data, 7-day access, 1 project, 1 seat); Starter ($30/mo, 3 GB data, 30-day access, unlimited projects/seats); Pro ($150/mo, 10 GB data, 6-month access, unlimited projects/seats); Enterprise (custom, on-premise)

L

Langfuse

Free

AI observability

Open-source AI engineering platform to debug, monitor, and improve LLM applications and agents

Hobby (free): 50k units/month, 30 days data access, 2 users. Core: $29/month, 100k units/month included, 90 days data access, unlimited users. Pro: $199/month, 100k units/month included, 3 years data access, high rate limits, SOC2 & ISO27001. Enterprise: $2,499/month. Additional usage: $8/100k units.

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Lunary

AI observability

Build AI agents with confidence

Team plan at $20/user/month (50,000 events/month included, 300 AI Playground queries/month, unlimited projects, 1 year history). Enterprise is custom pricing. Usage above included allowance billed separately.

M

MLflow

Free

AI observability

The leading open source AI engineering platform for Agents, LLMs & Models

100% open source under Apache 2.0 license. Forever free, no strings attached.

O

Opik

Free

AI observability

Open-source AI observability & evaluation platform for the agentic era

Free tier available (no credit card required); enterprise plan available (contact sales). Open-source version is free to self-host.

P

Patronus AI

AI observability

Simulating the World's Intelligence

Custom/contact-us pricing for frontier AI labs seeking training data, tasks, and simulated environments for reinforcement learning.

P

Phoenix

Free

AI observability

The open-source platform for AI agent development, tracing, and evaluation

AX Free (free, 25k spans/mo, 1 GB, 15-day retention, SaaS); AX Pro ($50/mo, 50k spans/mo, 10 GB, 30-day retention, SaaS); AX Enterprise (custom, SaaS or Self-Hosted)

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PromptLayer

Free

AI observability

The collaboration layer for AI engineering teams — prompt CMS, eval harness, and observability stack

Free tier at $0/month (5 users, 2.5k requests/month); Pro at $49/month; Team at $500/month (25 users, 100k+ requests/month); Enterprise at custom pricing. Pay-as-you-go overages: $0.003/txn (Pro), $0.002/txn (Team).

T

Traceloop

Free

AI observability

LLM reliability platform that turns evals and monitors into a continuous feedback loop

Free tier: $0/mo, up to 50K spans/month, up to 5 seats, 24-hour data retention. Enterprise: custom pricing (contact sales), >50K spans/month, unlimited seats, custom data retention, SOC 2, on-prem option. Available on AWS, GCP, and Azure Marketplaces.