Fact0
Tamper-evident audit trails for AI agents that pass enterprise security reviews.
Adopt Fact0 if you're an AI startup that needs to close enterprise deals: the signed evidence packs and hash-chained ledger are exactly what CISOs ask for. The free tier caps at 30K events and Pro jumps to $79/mo, but for compliance-critical agent deployments it's a justified expense. Compared to generic logging tools like Datadog or Splunk, Fact0's agent-specific features—execution DAG replay, tool boundary validation, and evidence packs—give you a clear advantage in security reviews.
Verified 3d ago · liveness 79/100 · cite: rightaichoice.com/tools/fact0
- AI startup founders closing enterprise deals with evidence packs
- Engineers deploying AI agents in regulated industries (fintech, healthcare, legal)
- Compliance officers verifying agent tool boundaries and data access
- Fintech companies auditing loan and payment agent approvals
- Teams needing general-purpose logging or observability
- Users wanting real-time log streaming without batching
- Hobbyists needing >30K events without paying for Pro
We scan live Reddit threads, YouTube comments, X posts, G2 reviews and other communities — and hand you an honest verdict in under a minute.
- Honest verdict, not marketing
- Real pros & cons from real users
- Attributed quotes with receipts
3 free scans · no card needed
Skip Fact0 if you don't need to prove agent behavior to an enterprise or regulator, if 30,000 events/month is too low for your development volume and you can't justify $79/mo, or if you only need general-purpose logging without cryptographic audit trails.
Going past 30,000 audit events/month on Free requires upgrading to Pro at $79/mo, which is a big jump for small teams.
Free tier with 30K events is great for startups. Pro at $79/mo is mid-range; cheaper than Sentry's team plans but pricier than basic logging. Enterprise is custom, but for compliance-critical deployments it's justified versus building in-house.
In short
Fact0 — Tamper-evident audit trails for AI agents that pass enterprise security reviews. Best for AI startup founders closing enterprise deals with evidence packs, Engineers deploying AI agents in regulated industries (fintech, healthcare, legal), Compliance officers verifying agent tool boundaries and data access. Free to start; paid plans from $79/mo.
What's new in Fact0
Checked 3 days agoAcross the latest 4 updates: 1 feature update and 3 changelog entries.
v1.2.2 - Observability Analytics Fix & Dashboard UX
Fixed a 500 error in analytics and added contextual help sheets and page-local tours to six dashboard pages.
Go SDK v1.0.4
Resolved Go module path resolution issues for correct package installation.
SDK v1.0.5 / v1.0.3
Fixed Python event_id preservation and a Go socket leak in the HTTP retry loop.
v1.2.1 - LLM Traces Dashboard & Database Immutability
Added LLM Traces dashboard, PostgreSQL trigger for audit immutability, share link token reveal, and evidence pack public keys.
What people actually say about Fact0 — is it worth it?
We ran a structured research pass across product reviews, community discussions, and post-purchase forum threads to surface the patterns vendors won't publish themselves. Below: the recurring strengths, the hidden costs people mention most, and the cohort that consistently regrets adopting this tool.
28 mentions across 3 sources (YouTube, Product Hunt, Bluesky) · researched Jul 4, 2026.
- +Hash-chained ledger with SHA-256 and Ed25519 cryptography provides tamper-evident logs.
- +Supports multiple SDKs (Python, TypeScript, Go) for flexibility.
- +Natively integrates with OpenTelemetry, LangChain, LangGraph, and FastAPI.
- +Generates signed evidence packs (PDF/JSON) and read-only auditor share links.
- +Free tier offers 30,000 events/month — good for early prototyping.
- −Zero real user feedback — cannot verify reliability or ease of use.
- −Only 18 Product Hunt upvotes, no organic community buzz anywhere.
- −Off-topic YouTube and Bluesky posts waste scraping effort.
- −No reviews from Reddit, HN, GitHub, or App Store to trust.
- −Potential lock-in: proprietary audit ledger if no export standard.
- • Overage fees not specified
- • Enterprise pricing is opaque
Viability Score
How well maintained and how widely used is Fact0? Built from what the vendor actually publishes (docs, changelog, tutorials, integrations, pricing), whether the site is live, and how much real users discuss it. How we calculate this
Last calculated: September 2026
How we score →Key Features
- Hash-chained audit ledger with SHA-256 integrity
- Ed25519 cryptographically signed evidence packs
- PDF and JSON evidence exports
- Read-only auditor share links
- Execution DAG visualization and replay
- LLM Traces dashboard
- Fact0 Spotlight AI search over audit logs
- Real-time webhook alerts
- Slack and PagerDuty alerts
- Versioned Prompt Registry
- GDPR-compliant purge
- Database-level audit immutability (PostgreSQL trigger)
- Python SDK
- OpenTelemetry integration
About Fact0
Fact0 is a runtime audit layer built for AI agent teams that need to prove tool boundaries, data exfiltration guards, and human-in-the-loop policies during enterprise security reviews. It creates a hash-chained ledger secured by Ed25519 cryptography, giving you mathematically verifiable logs of every agent action. You can log your first audit event in under a minute with the Python SDK, and export signed evidence packs (PDF or JSON) with read-only auditor share links. Fact0 integrates natively with OpenTelemetry and agent frameworks like LangChain, LangGraph, LlamaIndex, CrewAI, and AutoGen, plus OpenAI Agents SDK, Google ADK, and Mastra. It also offers a dedicated plugin for auditing Claude Code sessions. The free tier gives you 30,000 events/month, Pro is $79/mo for 500,000 events, and Enterprise offers custom volume, self-hosting, SAML/SSO, and BYOK. Whether you're a founder closing enterprise deals or an engineer in fintech, healthcare, or legal, Fact0 gives you a defensible edge in security reviews.
Behind the Verdict
Fact0 is a purpose-built audit layer for AI agents, not another logging tool. It stands out by focusing on the specific fears enterprise CISOs have: tool boundaries, data exfiltration, and human-in-the-loop validation. The tamper-evident ledger is not just a log; it's a cryptographic guarantee that can be verified by a third-party auditor, which is a huge deal when you're in a security review. The recent changelog shows active development, including an LLM Traces dashboard, database-level audit immutability, and Fact0 Spotlight for natural-language queries. The free tier is generous for a startup, and the Pro tier at $79/mo is reasonable for teams already paying for LLM calls. However, the free tier's 30K events limit can be restrictive for serious development, and the jump to Pro is steep if you're not yet closing deals. Also, self-hosting and BYOK are only on Enterprise, which requires a sales conversation. Overall, if your issue is 'prove our agent is safe' to an enterprise, Fact0 is one of the few tools that gives you a direct answer.
Researching Fact0? Get your full AI stack in 60 seconds.
Free, no signup — tell us your goal and get tools matched to your budget & existing stack.
Real-world workflow fit
Concrete scenarios for the personas Fact0 actually fits — and what changes day-one when you adopt it.
You're in an enterprise security review and need to prove your agent's tool permissions and data access.
Outcome: Export a signed evidence pack and share a read-only link, passing the review in minutes.
You need to audit every loan approval action in your agent for regulatory compliance.
Outcome: Log each action with actor and outcome, then replay the execution DAG to demonstrate accountability.
You need to verify that no patient PII was exposed during agent operations.
Outcome: Run Spotlight queries to find any PII access events and generate a HIPAA-ready evidence pack.
Use Cases
- Prove every tool permission and data access in fintech loan agents for regulators
- Track patient data access in healthcare administrative assistants with zero PII exposure
- Show exactly what an autonomous support bot changed, refunded, or escalated
- Audit document deletes, shares, and AI-generated summaries for legal/HR workflows
- Generate SOC-2 and HIPAA-ready evidence packs for enterprise security reviews
- Replay failed agent runs to debug and prove what happened
- Monitor real-time LLM metrics and error rates in production
Models Under the Hood
as of 2026-08-30
Limitations
- Free plan caps at 30,000 events/month with 30-day retention and only 5 evidence exports/month.
- Pro tier limits to 500,000 events/month.
- Self-hosting and BYOK are only available on the Enterprise plan, which requires a sales conversation.
as of 2026-08-31
Verification history
We have re-verified Fact0 6 times since . Each pass re-reads the vendor's own pages and re-checks every listed field against that evidence; passes where nothing had changed are marked as such.
- — re-verified summary, description, our verdict, our analysis, pricing model, pricing tiers, features, integrations, who it suits, who should skip it
- — re-verified summary, description, our verdict, our analysis, pricing model, pricing tiers, features, integrations, who it suits, who should skip it
- — re-verified summary, description, our verdict, our analysis, pricing model, pricing tiers, features, integrations, who it suits, who should skip it
- — re-verified summary, description, our verdict, our analysis, pricing model, pricing tiers, features, integrations, who it suits, who should skip it
- — re-verified summary, description, our verdict, our analysis, pricing model, pricing tiers, features, integrations, who it suits, who should skip it
- — re-verified summary, description, our verdict, our analysis, pricing model, pricing tiers, features, integrations, who it suits, who should skip it
Free to cite with attribution — this page re-verifies continuously.
12-month cost
Project the real annual outlay, including the implied monthly cost when only an annual tier is published.
Vendor list price only. Add-on usage, seat overages, and contract minimums are surfaced under Hidden costs & gotchas.
Plans compared
For each published Fact0 tier: who it actually fits, and what it adds vs. the previous tier. Cross-reference the cost calculator above for projected annual outlay.
Free
$0/mo
Ideal for
Solo developers or startups needing to instrument agents and pass a first security review without cost
What this tier adds
Entry tier with 30,000 audit events/mo, 5 GB storage, 30-day retention, 1 team seat, and 5 evidence exports/mo.
Pro
$79/mo
Ideal for
Teams shipping AI agents in production with collaborative tools, active share links, and role-based access control
What this tier adds
Adds 500,000 events/mo, 90-day retention, 5 team seats, Slack & PagerDuty alerts, execution DAG replay, and unlimited active share links.
Enterprise
Custom
Ideal for
Large organizations with custom compliance needs, self-hosting, and dedicated support
What this tier adds
Unlimited events, storage, and seats; adds SAML/SSO, SCIM provisioning, BYOK, self-hosting, and custom SLAs.
Where the pricing makes sense
The company stage and team size where Fact0's pricing actually pencils out — and where peers do it cheaper.
Free tier with 30K events is great for startups. Pro at $79/mo is mid-range; cheaper than Sentry's team plans but pricier than basic logging. Enterprise is custom, but for compliance-critical deployments it's justified versus building in-house.
Setup time & first value
How long it actually takes to get something useful out of Fact0 — broken out by persona, not the marketing-page minute.
Install the Python SDK and log your first event in under a minute. For full setup including execution tracing and dashboard configuration, expect 15-30 minutes. Integrations with LangChain or OpenTelemetry can be added in less than an hour.
Switching to or from Fact0
How to bring data in from common predecessors and how to get it back out — written for the switcher, not the buyer.
- →From generic logging (e.g., Datadog): You can start logging agent-specific events with Fact0 in parallel, using the SDK to send both audit and telemetry data while keeping your existing dashboards.
- ↗To custom logging: Since Fact0 uses standard OpenTelemetry, you can point your OTel collector elsewhere and retain your existing traces.
Integrations
Resources & Guides
- Documentationfact0.io
Docs · Fact0
Full product docs from fact0.io
- Resourcefact0.io
Changelog · Fact0
Helpful link from fact0.io
- Quickstartfact0.io
Quickstart · Fact0
Get up and running fast from fact0.io
- API Referencefact0.io
Python · Fact0
Methods, params, types from fact0.io
- Documentationfact0.io
Integrations · Fact0
Full product docs from fact0.io
- Documentationfact0.io
Api Reference · Fact0
Full product docs from fact0.io
Tutorials & Learning
Official links
Tools that pair well with Fact0
Common stack mates teams adopt alongside Fact0, with the specific reason each pairing earns its keep.
Credo AI
Enterprise AI governance platform for agents, models, and apps, from intake to runtime.
SailPoint
Enterprise-grade identity governance securing humans, machines, and AI agents with adaptive access controls
Cyberhaven
AI-native data security platform for the agentic enterprise, with DSPM, DLP, and IRM.
Featured Head-to-Head Comparisons
Fact0 vs Sublime Security
Choose Fact0 if you need cryptographically verifiable audit trails for AI agents to pass enterprise security reviews, especially in regulated industries. Choose Sublime Security if you're an enterprise security team defending against advanced email threats like BEC/VEC with custom detection and low false positives. They serve entirely different domains.
Fact0 vs Audioeye
Fact0 and AudioEye are incomparable tools serving vastly different needs. Fact0 is for AI agent auditability in regulated industries, while AudioEye tackles web accessibility compliance. Choose Fact0 if you need tamper-evident agent logs to close enterprise deals; choose AudioEye if you need ADA/WCAG compliance to avoid lawsuits.
Fact0 vs Push Security
Fact0 and Push Security serve entirely different needs: Fact0 is a cryptographic audit trail for AI agents, essential for compliance in regulated industries, while Push Security is a browser-based threat detection platform for identity and security teams. Choose Fact0 if you need provable agent logs to pass enterprise security reviews; choose Push Security if you must defend against AiTM phishing, session hijacking, and AI tool data leaks.
Alternatives to Fact0
View allCredo AI
Enterprise AI governance platform for agents, models, and apps, from intake to runtime.
SailPoint
Enterprise-grade identity governance securing humans, machines, and AI agents with adaptive access controls
Cyberhaven
AI-native data security platform for the agentic enterprise, with DSPM, DLP, and IRM.
Frequently Asked Questions
Used Fact0? Help shape our editorial sentiment research.