API Documentation — 13D Watch

Base URL

https://13dwatch.com

All public endpoints are CORS-open (Access-Control-Allow-Origin: *) and edge-cached at Cloudflare for 5 minutes. Pass a query string to bust the cache.

Endpoints

GET/api/feed

Returns the 60 most recent Schedule 13D and 13G filings, fully enriched with insider activity (Form 4, last 90d), institutional consensus (10 elite filers), FINRA short interest, multi-activist cluster count, filer history, and AI analyst brief with intent classification.

$ curl https://13dwatch.com/api/feed | jq '.filings[0]'
{
  "accession_number": "0001193125-26-173780",
  "form_type": "SCHEDULE 13D",
  "filing_date": "2026-04-23",
  "date_of_event": "2026-04-20",
  "filer_name": "Illumina Innovation Fund II, L.P.",
  "filer_cik": "0002104204",
  "issuer_name": "Alamar Biosciences, Inc.",
  "issuer_cik": "0001998213",
  "issuer_ticker": "ALMR",
  "ticker_source": "filing",
  "cusip": "010911105",
  "securities_class": "Common Stock, par value $0.0001 per share",
  "shares_owned": 5856536,
  "percent_owned": 9.6,
  "purpose": "The information set forth in Item 3 ...",
  "filing_url": "https://www.sec.gov/Archives/edgar/data/2104204/...",
  "filer_history": null,
  "issuer_cluster": { "filings_in_window": 2, "window_days": 90 },
  "insider_activity": null,
  "institutional_consensus": null,
  "short_interest": null,
  "ai_brief": {
    "summary": "Illumina's corporate venture arm filed a 13D on ALMR ...",
    "intent": "strategic",
    "confidence": "medium",
    "model": "anthropic/claude-sonnet-4.6"
  }
}

GET/api/filing/{accession_number}

Returns one specific filing with full enrichment: insider transactions on the issuer (last 365d, full transaction list), institutional consensus, latest short interest, every other 13D/G ever filed on this issuer, every other filing by this filer.

$ curl https://13dwatch.com/api/filing/0001193125-26-173780

GET/api/health

Pipeline health and row counts for the underlying data moat. Use to verify the moat is fresh before relying on the feed for production decisions.

$ curl https://13dwatch.com/api/health
{
  "status": "ok",
  "as_of": "2026-04-30T...",
  "counts": {
    "activist_filings": 148,
    "insider_transactions": 928,
    "institutional_holdings": 11181,
    "short_interest": 171325
  }
}

POST/api/contact

Pilot inquiry intake. Body: { name, email, firm, aum_band, message }. Honeypot field company_website filtered. Rate-limited 5 per IP per hour.

POST/api/alerts/subscribe

Create an email alert subscription. Body:

{ email, type: "filer"|"issuer"|"intent"|"any", filer_cik?, issuer_ticker?, issuer_cik?, intents?, form_types?, min_percent? }

. Sends a verification email on success.

$ curl -X POST https://13dwatch.com/api/alerts/subscribe \
    -H "content-type: application/json" \
    -d '{
      "email": "you@yourfund.com",
      "type": "issuer",
      "issuer_ticker": "LUV"
    }'

Authentication

Public endpoints require no authentication. Admin endpoints (warm AI briefs, publish blog articles, list leads, process alerts) are gated by an x-admin-token header issued only to internal automation.

For programmatic alerts at high volume, custom webhooks, or commercial SLAs (99.9% uptime, <100ms p99 latency), contact contact@13dwatch.com.

Rate limits

Public read endpoints: no hard limit. Edge-cached at Cloudflare for 5 minutes — sustained 200+ rps is fine for a single client.
Pilot inquiry: 5 submissions per IP per hour.
Alert subscription: 5 unverified subscriptions per IP per hour.

Stability and versioning

The current API is v1. Breaking changes will ship behind /api/v2/ with v1 supported for 12 months in parallel. Field additions are non-breaking and ship without notice.

Source code (Cloudflare Worker that serves this API) is in a private repo. The data ingestion worker (data-moat-ingest) is in a separate private repo. Pricing for source-license + co-development is available on request.

The 13D Watch public API.

Base URL

Endpoints

Authentication

Rate limits

Stability and versioning

Build on the feed.