Choose Your Plan
Scale your claim verification with the right plan.
Alpha: limits and features may change; no SLA.
Personal
- 100 scans/month
- Markdown export
- All export formats
- Email support
Cancel anytime. No lock-in.
Pro
- 500 scans/month
- PDF export
- Batch scan
- Team workspaces
- Notifications
- API key (100 billed claims/month included)
Cancel anytime. No lock-in.
Enterprise
- Scan allowance set in your contract
- Everything in Pro
- Multi-model consensus verification
- Audit trails
- Dedicated support
Prices exclude sales tax and VAT. Any tax due is calculated at checkout from the location you enter.
API key
An API key lets your code and agents check AI output with Faultline over its REST API.
- $10 a month, 100 billed claims a month included.
- Then $0.10 per billed claim.
- A key stops at 1,000 billed claims a month.
A claim is billed only when Faultline returns a verdict backed by a source it found. A claim it could not check against a source is not billed. Claims marked unverified, and claims lost to a provider error, are not billed either.
Tax is added on top where it applies, calculated at checkout from the location you enter.
After payment, your key is shown once on your account page. Copy it then.
Alpha: limits and features may change; no SLA.
MCP
The same key works on the hosted MCP server at https://faultline-api.fly.dev/mcp (Streamable HTTP). Send the key in the x-api-key header.
The tool is verify_claims.
Billed the same way as the REST API, per billed claim.
Claude Code config
{
"mcpServers": {
"faultline": {
"type": "http",
"url": "https://faultline-api.fly.dev/mcp",
"headers": { "x-api-key": "<your API key>" }
}
}
}Or run the server on your machine (stdio). With the key set, scans run on the hosted API and are billed the same way.
FAULTLINE_API_KEY=<your API key> npx -y -p @nxtg/faultline faultline-mcp
Questions
What counts as a scan?
One verification run over a block of text or a file. Faultline extracts the claims, checks the most important factual ones against live sources (up to 8 per scan), and returns a risk band plus a list of anything it could not verify. Your plan’s monthly limit is the number of these runs. A deep scan checks every factual claim and counts as 1 scan per 8 factual claims; you see the count before you confirm.
Is there a free plan?
Yes. The Free plan gives you 5 scans per month with JSON and SARIF export and no card required. Personal ($19/mo) raises that to 100 scans, and Pro ($49/mo) to 500.
Do prices include tax?
No. Prices exclude sales tax and VAT. Stripe calculates any tax due at checkout from the location you enter, and it shows on the checkout page before you pay.
Can I cancel anytime?
Yes. Personal and Pro are month-to-month with no lock-in and no contract. Sign in, open Pricing, and select Manage or cancel subscription to use the Stripe-hosted billing portal. The plan stays active until the end of the billing period. For assistance, email faultline.web@nxtg.ai.
Whose AI provider keys do my scans run on?
Faultline’s. Hosted scans run on Faultline’s managed provider keys, so you never need your own for them. Free, Personal and Pro are capped by your monthly scan limit. Enterprise scan allowances are set in your contract.
Which AI providers does Faultline verify against?
Free, Personal and Pro scans are checked by Google Gemini against sources Faultline finds with Parallel. Enterprise adds multi-model consensus with OpenAI and Anthropic. Pro and Enterprise also unlock batch scanning, PDF audit export, team workspaces, and API access. Pro includes an API key with 100 billed claims a month.
How is Faultline different from a grammar or plagiarism checker?
Those check style and originality. Faultline checks whether the factual claims in AI output are true: it checks the most important ones against live sources and flags fabricated references and hallucinations before they ship.
Do you store the text I scan?
Your text is sent to the Faultline engine and to the AI model providers that check it; the engine does not write it to storage. When you are signed in, each scan (its full text and its results) is saved to your own history for 2 years; only you can open it, and you can delete it at any time. Without an account, your history stays in your browser. A scan you share is stored for 30 days. Details are on the Privacy page.