Weights & Biases sits at $245M Series C as the production-ML observability anchor, and CoreWeave's 2024 acquisition of W&B for ~$1.7B reset the upper bound for the category. Braintrust's $80M Series B targets the LLM-app eval layer specifically, where Arize AI, Galileo AI, Comet, and Langfuse compete on trace-level inspection and offline-to-online eval flow. Helicone overlaps on the gateway side. Cleanlab, Anomalo, and Credo AI extend the surface into data-quality monitoring and AI governance, the audit trail that EU AI Act compliance now formally demands. DataRobot and Dataiku represent the legacy enterprise-MLOps incumbents pivoting toward agent observability.
CATEGORY
Best AI Observability Tools
43 tools compared · 2026
Trace, eval, and govern LLM applications and agents from prompt iteration to production drift
43 ai observability startups tracked, with the largest concentration in US. Total tracked funding: $1.1B.
Tracked
43
Total Raised
$1.1B
Countries
9
Active Deals
1
1 
NeuBird Santa Clara, US $63.8M 2 
Traversal New York, US $48M 3 
Ciroos San Jose, US $21M 4 
Sifflet Paris, FR $35.8M 5 
ThoughtData Acton, United States — 6 
Observe San Mateo, US $270M 7 
Portkey San Francisco, US $18M 8 
Raindrop San Francisco, US $15M 9 
TensorZero New York, US $7.3M 10 
Confident AI San Francisco, US $2.2M 11 
HoneyHive New York, US $7.4M 12 
Maxim AI Bengaluru, IN $3M
Funding by year — AI Observability
2021 → 2026Market overview
Key trends 2026
- Eval-first overtakes monitor-first. Braintrust and Galileo lead by treating offline evals as the core artifact, not afterthought dashboards.
- EU AI Act reshapes governance demand. Credo AI sees enterprise budget unlock for documented AI risk controls.
- W&B acquisition raises the ceiling. CoreWeave's ~$1.7B deal proves observability can clear unicorn-plus exits.
Benchmarks vs global
Largest exit
~$1.7B (W&B to CoreWeave)
vs Braintrust $80M Series B ↑
Median LLM-app trace cost
$0.001-0.005/trace
vs free OSS Langfuse ↓
Enterprise AI-governance budget growth
2-3x YoY (Credo AI cohort)
vs flat 2022 baseline ↑
Top countries
By startup countStage breakdown
Latest round typeTop investors backing AI Observability
See all → M
Mayfield
5 deals
Y Combinator
5 deals
Sinewave Ventures
3 deals
SG
StepStone Group
3 deals
M12 — Microsoft's Venture Fund
3 deals
TB
Two Bear Capital
2 deals
SI
Singtel Innov8
2 deals
AC
Ansa Capital
2 deals
MC
Mangrove Capital Partners
2 deals
Prosperity7 Ventures
2 deals
EQT Ventures
2 deals
Coatue Management
2 deals
FAQ
Frequently asked
What's the difference between Arize, Braintrust, and Langfuse?
Arize AI sits closest to traditional ML monitoring with strong drift and embedding tooling. Braintrust prioritizes prompt-and-eval iteration loops for LLM app builders. Langfuse is open-source-first and self-hostable, often chosen by teams with strict data-residency requirements.
Which AI observability startup has raised the most?
Weights & Biases leads at $245M Series C and was acquired by CoreWeave in 2024 for ~$1.7B. Braintrust follows with an $80M Series B. Most other category players — Arize, Galileo, Helicone, Langfuse — sit at earlier stages.
Do I need observability if I'm just calling the OpenAI API?
For toy projects no. For anything in production yes — at minimum a logging gateway like Helicone catches latency spikes, cost runs, and bad outputs. Once you have evaluators, Braintrust or Langfuse let you regression-test prompt changes before deploying them.
Recent rounds in AI Observability
All rounds →| Date | Startup | Round | Amount |
|---|---|---|---|
| Apr 2026 | InsightFinder | Series B | $15M |
| Apr 2026 | NeuBird | Venture | $19.3M |
| Mar 2026 | Hyground | Pre-Seed | Undisclosed |
| Feb 2026 | Selector AI | Venture | $32M |
| Feb 2026 | Braintrust | Series B | $80M |
| Jan 2026 | Sazabi | Seed | $500K |
| Dec 2025 | Raindrop | Seed | $15M |
| Nov 2025 | AlertD | Pre-Seed | $3M |
All AI Observability startups
Page 1NeuBird
Hawkeye, an agentic AI SRE that autonomously diagnoses and resolves production issues
Raised
$63.8M
Stage
VENTURE
Traversal
The AI SRE agent that finds root causes in complex production systems
Raised
$48M
Stage
SEED AND SERIES A
Ciroos
Multi-domain AI SRE teammate that automates and augments operations and incident response
Raised
$21M
Stage
Seed
Sifflet
AI-ready data observability platform to monitor pipelines, quality, and lineage end to end
Raised
$35.8M
Stage
VENTURE
ThoughtData
PRIVATEUnified AIOps observability with root-cause analysis and remediation
Observe
AI-native observability platform built on a data lake to replace Splunk and Datadog
Raised
$270M
Stage
S-C
Portkey
The control plane for production AI
Raised
$18M
Stage
Seed
Confident AI
DeepEval-powered LLM evaluation and observability
Raised
$2.2M
Stage
Seed
TensorZero
Open-source stack for building industrial-grade LLM applications
Raised
$7.3M
Stage
Seed
Raindrop
Sentry for AI agents — monitoring that catches silent failures in production
Raised
$15M
Stage
Seed
Maxim AI
GenAI evaluation, simulation and observability platform for AI agents
Raised
$3M
Stage
Seed
HoneyHive
Observability and evaluation for production AI agents
Raised
$7.4M
Stage
Seed
Langfuse
Open source LLM engineering platform for debugging, analyzing, and iterating on LLM applications
Raised
$8M
Stage
Seed
Coval
Simulation and evaluation platform for voice and chat AI agents, modeled on self-driving car testing.
Raised
$3.3M
Stage
Seed
AlertD
Agentic AI for SRE and DevOps that surfaces AWS insights in plain language
Raised
$3M
Stage
Pre-S
Phoebe
Building an AI-driven immune system for software, using swarms of AI agents that continuously
Raised
$17M
Stage
Seed
OpenObserve
AI-native, open-source observability for logs, metrics, and traces
Raised
$10M
Stage
S-A
Foundational
Code-aware data quality and lineage for AI-ready data
Raised
$8M
Stage
Seed
Revefi
Zero-touch platform that monitors data quality, warehouse spend, performance and usage
Raised
$30.5M
Stage
S-A
Weights & Biases
VerifiedThe AI developer platform
Raised
$245M
Stage
S-C
Clawvisor
Purpose-based authorization gateway that keeps AI agents from going rogue.
Raised
$500K
Stage
Seed
Superlog
AI-native observability that installs itself and ships pull requests to fix the bugs it finds.
Raised
$500K
Stage
Seed
Sazabi
The AI-native observability platform for fast-moving engineering teams
Raised
$500K
Stage
Seed
LangWatch
Platform for LLM evaluations, agent testing and observability
Raised
$1.1M
Stage
Pre-S