Fiddler AI
Enterprise platform for monitoring, evaluating and guarding ML models and AI agents.
Updated · AppBreakup editorial · Web, Self-hosted
Is Fiddler AI free?
Free plan, plus paid plans
- Developer plan:
- $0.002 per trace
- Free plan:
- Real-time guardrails
Checked on Fiddler AI's site Nov 8, 2026
Full Fiddler AI pricing and plansSwitch from Fiddler AI to
All 4
Evidently AIOpen source
DatadogStarting price: Infrastructure Pro, $15 per host/month billed annually
New RelicStarting price: $10 for the first full user, then $99 per user (Standard)
- Verified facts
- 4 of 4
- Alternatives ranked
- 4
- Approved reviews
- 0
- Visits sent from here
- 0
About Fiddler AI
Fiddler AI is an observability and governance platform for companies running machine learning models and LLM agents in production. It began with monitoring for predictive models (drift, performance, explainability) and now centres on agents: tracing what each agent did, running evaluations from testing through production, and enforcing policy with guardrails that check for hallucinations, toxicity, PII and prompt injection. Those guardrails and evaluations run on Fiddler's own small models rather than calling an outside LLM, which keeps latency and per-check cost down. It is built for large, regulated organisations such as banks, insurers, healthcare and government, and can run as SaaS, in your own VPC or on-premises. There is a free tier limited to guardrails, a usage-priced developer plan charged per trace, and enterprise contracts through sales. Smaller teams after simple prompt logging may find it heavier than they need.
Best for: Regulated enterprises that need agent observability, guardrails and AI governance in one platform.
Fiddler AI pricing (checked Nov 8, 2026)
Each line is quoted from Fiddler AI's own site, with the page it came from.
| Plan or term | What it says | Checked | Source |
|---|---|---|---|
| Free plan | Real-time guardrails | Nov 8, 2026 | fiddler.ai |
| Developer plan | $0.002 per trace | Nov 8, 2026 | fiddler.ai |
Pros and cons
What works
- Monitors both predictive ML models and LLM agents in one place
- Guardrails run on its own models, so checks don't add outside LLM API costs
- Can be deployed as SaaS, in your VPC or on-premises
- Governance and compliance features aimed at regulated industries
Why people leave
- Free plan covers guardrails only, not full observability
- Not open source, unlike Evidently or Langfuse
- Enterprise features and on-prem deployment need a sales contract
Fiddler AI vs Evidently AI, Datadog and New Relic
From each app's listing and the prices verified on its own site. A dash means we haven't verified it yet.
| Attribute | Fiddler AI | Evidently AI | Datadog | New Relic |
|---|---|---|---|---|
| Pricing | Free plan + paid | Open source | Free plan + paid | Free plan + paid |
| Verified price | $0.002 per trace | — | Infrastructure Pro, $15 per host/month billed annually | $10 for the first full user, then $99 per user (Standard) |
| Free plan | Real-time guardrails | Free app | Yes, up to 5 hosts with 1-day metric retention | 100 GB data ingest/month |
| Open source | No | Yes | No | No |
| Self-hostable | No | Yes | No | No |
| Platforms | Web, Self-hosted | Self-hosted, Web | Web, iOS, Android | Web, iOS, Android |
Top Fiddler AI alternatives
See all 4- 1Evidently AI68.8
Open-source and free to self-host, covering the same mix of ML drift monitoring and LLM evaluation.
- 2Datadog66.1
LLM observability alongside the APM and infrastructure monitoring many enterprises already pay for.
- 3New Relic57.5
AI monitoring sits in the same APM platform as app traces and logs, handy for teams already paying for New Relic.
- 4
Weights & Biases51.2Hosted experiment tracking plus LLM tracing and evaluation, popular with model-training teams.
Why people left Fiddler AI
In reviewers' own words, from reviews of the apps they moved to. These are their opinions, not ours.
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Reviews
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Fiddler AI: common questions
What is Fiddler AI?
Fiddler AI: Enterprise platform for monitoring, evaluating and guarding ML models and AI agents. Best for regulated enterprises that need agent observability, guardrails and AI governance in one platform. Available for Web, and you can host it yourself.
Is Fiddler AI free?
Fiddler AI has a free plan and paid plans. Free plan: Real-time guardrails (checked on Fiddler AI's own site).
How much does Fiddler AI cost?
Fiddler AI is free with paid plans. Free plan: Real-time guardrails; Developer plan: $0.002 per trace. Checked on Fiddler AI's own site, November 2026.
Is Fiddler AI open source?
No, Fiddler AI is not open source. Open-source alternatives include Evidently AI.
What platforms does Fiddler AI run on?
Fiddler AI is available for Web and Self-hosted.
What are the best alternatives to Fiddler AI?
The highest-ranked Fiddler AI alternatives right now are Evidently AI, Datadog and New Relic. See the full ranked list for pricing, platforms and verified facts.
Fiddler AI vs Evidently AI: what's the difference?
Fiddler AI is free with paid plans; Evidently AI is free and open source. Evidently AI is open source and Fiddler AI is not. Both run on Web.