CiteGuard

Per-claim citation verification for AI-generated text. CiteGuard fetches every cited source and tells you whether it actually supports the claim — with a quoted evidence span, so you can verify the verdict yourself in seconds.

Built for the age of vibe citing: AI-drafted reports full of citations that resolve to real URLs but don't say what the text claims they say.

What it does

Give CiteGuard a document (markdown or plain text) or explicit claim+URL pairs. For each claim it:

1. Fetches the cited source — with timeout handling, redirect tracking, a 5 MB cap, and an automatic archive.org fallback for dead links.

2. Checks source liveness — dead URLs, DOI redirects, and "soft 404s" (redirects that land on a homepage) are flagged explicitly.

3. Extracts the real content — boilerplate-stripped article text via Readability; PDFs supported.

4. Judges entailment — an LLM reads only the fetched source text (never its own world knowledge) and returns one of six verdicts.

Every verdict ships with a verbatim evidence quote, a confidence score, and full source status. Document audits also return a citation integrity score (0–100).

CiteGuard never overclaims: if it can't fetch a source, it says so instead of judging blind, and borderline cases land in uncertain — the goal is to make human verification 10× faster, not to replace it.

Related MCP server: Fact Check MCP

Quick start (MCP)

Add to Claude Code / Claude Desktop / any MCP client:

{
  "mcpServers": {
    "citeguard": {
      "command": "npx",
      "args": ["-y", "citeguard-mcp"],
      "env": {
        "CITEGUARD_JUDGE_PRESET": "qwen",
        "CITEGUARD_JUDGE_KEY": "sk-..."
      }
    }
  }
}

Tools exposed: verify_claims, check_document, check_links (liveness-only, needs no LLM key).

Quick start (CLI)

npm install -g citeguard

citeguard extract report.md   # show extracted claim/source pairs (no network)
citeguard links report.md     # dead-link check (no LLM needed)
citeguard check report.md     # full audit (needs judge configured)

Judge configuration

CiteGuard is model-agnostic — anything with an OpenAI-compatible chat endpoint works:

# Preset providers
export CITEGUARD_JUDGE_PRESET=qwen        # or: openai, anthropic
export CITEGUARD_JUDGE_KEY=sk-...

# Or any OpenAI-compatible endpoint
export CITEGUARD_JUDGE_URL=https://your-endpoint/v1
export CITEGUARD_JUDGE_MODEL=your-model
export CITEGUARD_JUDGE_KEY=sk-...

Hosted API

A free hosted endpoint (50 requests/day/IP) runs on Cloudflare Workers:

curl -X POST https://citeguard.YOUR-SUBDOMAIN.workers.dev/api/verify \
  -H "content-type: application/json" \
  -d '{"claims":[{"text":"The Eiffel Tower is 330 m tall.","source":"https://en.wikipedia.org/wiki/Eiffel_Tower"}]}'

Remote MCP endpoint: POST /mcp (streamable HTTP, stateless).

What CiteGuard is not

• Not an AI-text detector. It doesn't care who wrote the text — it checks whether cited sources support claims.

• Not a truth oracle. A supported verdict means the cited source says this, not this is true. Garbage source in, garbage support out.

• Not a search engine. It verifies the citations you have; it doesn't find better ones (yet).

Extraction formats

Markdown inline links, reference-style links, footnotes, bare DOIs (resolved via doi.org), bare URLs. APA-style parsing and PDF input documents are on the roadmap.

Development

git clone https://github.com/Franksterino/citeguard
cd citeguard
npm install
npm run typecheck
npx tsx src/cli.ts extract test/fixtures/sample.md

License

MIT