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Faultline MCP Server

answering

Faultline is answering right now. Last checked 2 min ago. Last commit 6 Nov 2026.

Checks the most important factual claims in AI output against live web sources by default.

Uptime history 50 hours of history
50 hours agonow
100.0%
Uptime 24h
92 of 92 checks
—
Tools
hidden behind auth
405 ms
Response time
average over 24h
1
Stars
last commit 6 Nov 2026

What the code does

We read the source, 1 d ago · rules 995398eba69f

Capabilities

What this server is able to do. For an MCP server this is often the job itself — a terminal server runs commands because that is what it is for. Listed so you know what you are plugging in, not as an accusation.

    return execSync(cmd, { cwd, encoding: 'utf8', stdio: ['pipe', 'pipe', 'pipe'] }).trim();

Is this your server and something here is wrong? Tell us — corrections are free and do not require a plan.

This code can reach further than it looks

We found places where it runs commands, builds paths or queries from values it is given. None of that is a flaw by itself — it becomes one when the code changes, and code changes quietly between releases. We re-read it on every one.

Three servers free · no card

Connect this server

Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 2 min ago.

run in your terminal
claude mcp add faultline --transport http https://faultline-api.fly.dev/mcp
Settings → Connectors → Add custom connector, then paste this address
https://faultline-api.fly.dev/mcp
~/.codex/config.toml
[mcp_servers.faultline]
url = "https://faultline-api.fly.dev/mcp"
.cursor/mcp.json
{
  "mcpServers": {
    "faultline": {
      "url": "https://faultline-api.fly.dev/mcp"
    }
  }
}
.vscode/mcp.json
{
  "servers": {
    "faultline": {
      "type": "http",
      "url": "https://faultline-api.fly.dev/mcp"
    }
  }
}

This endpoint answered with an authorization challenge. The server is running, but it did not say what kind of credentials it expects.

Endpoints

URLTransportStateLatencyChecked
https://faultline-api.fly.dev/mcp streamable-http needs auth 372 ms 2 min ago

Alternatives to Faultline

same job, measured the same way
T
Trinity Research
by humanified

Fact-check claims against live web sources: verdict, consensus, cited sources, PII redaction.

4 tools answering
M
MCP V1
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Sub-cent factual claim verification against live data sources.

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V
Verify MCP
by agentutil

Sub-cent factual claim verification against live data sources.

61 installs/wk local only
Verity
by clawdio777

Real-time fact-checking MCP. Verifies claims against live sources with structured verdicts.

58 installs/wk local only
Lenz Fact-Check
by lenz

Check the factual claims in a draft or an answer: a quick verdict, or a deep check with sources.

answering
Second Read
by sbanthia92

Reviews drafts: fact-checks claims against web sources and builds the strongest counter-case.

190 installs/wk local only
aieo
by web-casa

SEO and AI-search checks for a website's build output, fixed in the source files

local only
Datumline Agent Guard
by datumline

Checks an AI agent's 'done' against the files and URLs it claims. Missing = FALSE_DONE.

114 installs/wk local only

Faultline — questions

Answers built from our own checks of this server.

Why is there no tool list for Faultline?
The server answered our handshake with an authorization challenge, so it is running — but it will not describe its tools to an anonymous client. To see them you need to connect with your own credentials. We record it as alive, not as broken: 100.0% of checks in the last 24 hours got a reply.
Is Faultline working right now?
We send a real MCP handshake every 15 minutes. Over the last 24 hours 92 of 92 checks got a reply (100.0%), average response time 405 ms. The bar chart above shows every period we have measured.
How do I connect Faultline?
Copy the ready config from this page. We generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each in the form that client actually reads. It is a remote server, so there is nothing to install — the client connects to the address. You will need your own credentials: it refuses anonymous clients.
Does Faultline need an API key?
Yes. Every time we knock, Faultline answers with an authorization challenge instead of its tool list — that is how we know it is running and gated rather than broken. Bring your own credentials and it will talk.
How fast is Faultline?
It answers our handshake in 405 ms on average, which is faster than 32% of all working MCP servers we measure. The comparison comes from our own checks across the whole registry, every 15 minutes.
Is Faultline open source?
The code is open source: it is published under the Apache-2.0 licence, written in TypeScript, 1 stars on GitHub and 1 open issue. The licence covers the code in the repository, not the hosted service at faultline-api.fly.dev, which runs on its operator's own terms.