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 2Athina AI
Evaluation and monitoring platform that helps developers prototype, experiment with, evaluate
Raised
$3.5M
Stage
Seed
Traceloop
LLM observability and reliability built on the open-source OpenLLMetry standard
Raised
$6.1M
Stage
Seed
InsightFinder
AI-driven reliability and observability for IT systems and AI agents
Raised
$35M
Stage
S-B
AVIAN
Always-on AI thermal monitoring to prevent industrial fires and equipment failures
Raised
$2.6M
Stage
Pre-S
Telmai
Open-architecture, AI-driven data observability
Raised
$5.5M
Stage
Seed
PromptLayer
The prompt management workbench for LLM teams
Raised
$5M
Stage
Seed
Metaplane
Data observability platform that uses machine learning to automatically detect anomalies
Raised
$13.8M
Stage
S-A
Validio
Agentic data management platform that automates data quality, observability, lineage, and
Raised
$30M
Stage
S-A
Braintrust
The AI observability platform for building quality AI products at scale.
Raised
$80M
Stage
S-B
Deductive AI
AI SRE agents that root-cause production incidents in minutes
Raised
$7.5M
Stage
Seed
Selector AI
AI observability and network intelligence using LLMs, knowledge graphs and causal reasoning
Stage
VENTURE
Arize AI
The AI & Agent Engineering Platform for development, observability, and evaluation of LLM applications.
Raised
$132M
Stage
S-C
Hyground
Self-hosted sovereign AI SRE agent for Kubernetes and enterprise IT operations
Stage
Pre-S
Prefactor
Agent observability and evaluation that scores every production run in real time
Helicone
Helicone is an AI gateway and LLM observability platform that helps companies route, debug, and analyze their AI applications.
Galileo AI
The AI observability and eval engineering platform where offline evals become production guardrails.
Comet
The AI Developer Platform for building, debugging, and deploying reliable AI agents.
Anomalo
The autonomous data system for the agentic enterprise, enabling self-driving data through AI-powered monitoring, investigation, and reporting.
Cleanlab
Detect and remediate incorrect responses from any AI Agent, ensuring every output meets your standards for safety, compliance, and trust.