Enrichment Waterfall for n8n

A waterfall = try cheapest/fastest vendor first, fall through to more expensive/accurate vendors only when the previous fails. This is how Clay, Clearbit, and every production enrichment pipeline actually works.

The core pattern

Input (name, email, or domain)
  ↓
Vendor 1 (cheap, fast, ~60% hit rate) — e.g., Hunter.io
  ↓ IF no match
Vendor 2 (medium cost, ~80% cumulative) — e.g., Apollo
  ↓ IF no match
Vendor 3 (expensive / LLM extract, ~95% cumulative) — e.g., SerpAPI + LLM
  ↓ IF no match
Dead letter: log as "unenrichable"

At each step, a hit short-circuits the rest. You pay only for what the cheap vendors miss.

Ordering: cost × accuracy × rate limit

Order vendors by expected cost per successful enrichment, not sticker price. Calculate:

effective_cost = price_per_call / hit_rate

Example for email-from-name+company:

Vendor	Price/call	Hit rate	Effective cost
Hunter.io	$0.004	55%	$0.007
Apollo bulk	$0.01	75%	$0.013
SerpAPI + LLM extract	$0.02	90%	$0.022
Manual LinkedIn scrape	$0.05	60%	$0.083

Order: Hunter → Apollo → SerpAPI+LLM → dead letter. Effective cost per enriched lead ≈ $0.012 vs $0.083 if you'd started with the scraper.

n8n implementation

Structure

1. Trigger (Webhook / Schedule / Manual)
2. Set — normalize input (lowercase email, strip whitespace, extract domain)
3. MySQL / Google Sheets — check cache (was this already enriched in last 30 days?)
4. IF cache hit → return cached → END
5. HTTP Request: Hunter.io
6. IF match found → Set enriched data → merge back → END
7. HTTP Request: Apollo (on Hunter miss)
8. IF match → merge → END
9. HTTP Request: SerpAPI
10. Information Extractor (LangChain) — extract contact from SERP results
11. IF match → merge → END
12. MySQL insert — dead letter table

Critical configuration

Each HTTP Request node needs:

• continueOnFail: true — so one vendor's 500 doesn't kill the pipeline
• retry.maxTries: 2 with retry.waitBetweenTries: 3000
• Timeout: 10s. Waterfalls with 6 vendors at 30s timeouts = 3-minute-per-lead worst case
• Auth via n8n credentials, never inline

The IF check pattern

After each vendor, check BOTH response status AND payload content:

// In an IF node expression:
={{ 
  $('Hunter Request').item.json.error 
    ? false 
    : $('Hunter Request').item.json.data?.email != null 
}}

Don't just check .error — vendors often return 200 with empty results on a miss.

Cache layer (mandatory)

Enrichment data goes stale in ~30 days but doesn't change daily. Cache aggressively:

CREATE TABLE enrichment_cache (
  input_key VARCHAR(255) PRIMARY KEY,  -- normalized email/domain
  enriched_data JSON,
  source VARCHAR(50),                   -- which vendor hit
  enriched_at TIMESTAMP,
  INDEX idx_enriched_at (enriched_at)
);

Before calling ANY vendor, SELECT on input_key WHERE enriched_at > NOW() - INTERVAL 30 DAY. Cache hit rate of 40% is normal after a few weeks — that's 40% cost reduction for free.

LLM extract stage (the Stage 3 secret weapon)

When paid vendors miss, SerpAPI + LLM extract works 80%+ of the time:

1. HTTP Request → SerpAPI search: "{{ $json.first_name }} {{ $json.last_name }}" "{{ $json.company }}" site:linkedin.com
2. Information Extractor with schema:

   {
     "linkedin_url": "string",
     "title": "string",
     "location": "string",
     "confidence": "number (0-1)"
   }
   

3. IF confidence < 0.7 → treat as miss

Use Groq llama-3.3-70b-versatile for extract — it's fast enough that even at 90% hit rate, per-lead cost stays under 2 cents.

Rate limits (the silent killer)

Every vendor has limits. Hitting them burns waterfalls silently.

Vendor	Typical limit	n8n handling
Hunter.io	50/min (free tier 25/day)	Split In Batches size=1, Wait 1200ms between
Apollo	600/min enterprise	Usually fine at batch size 10
SerpAPI	Plan-dependent	Check headers, backoff if X-RateLimit-Remaining < 5

For high-volume pipelines, run the waterfall as a sub-workflow called from a Split In Batches parent with batchSize: 10, waitBetweenBatches: 60000.

Anti-patterns

• Parallelizing vendors. Running all 3 in parallel and picking the best defeats the point — you pay for all 3 on every lead. Waterfall = sequential with early exit.
• No dead letter. Unenrichable leads must go somewhere queryable so you can spot-check WHY they're missing. Otherwise vendor regressions go unnoticed.
• Same timeout across vendors. Cheap vendors are usually fast (set 5s). Scrapers need 30s. Tune per vendor.
• No vendor health monitoring. Add a dashboard query: hit rate per vendor per week. When Hunter's hit rate drops from 55% to 20%, you want to know immediately.

Output contract

Whatever the source, the waterfall should output a unified schema downstream consumers can rely on:

{
  "email": "string",
  "full_name": "string",
  "company": "string",
  "linkedin_url": "string|null",
  "title": "string|null",
  "enrichment_source": "hunter|apollo|serpapi_llm",
  "confidence": "number (0-1)",
  "enriched_at": "ISO timestamp"
}

Add a final Set node to normalize each vendor's response into this schema before returning.

Reference

• references/waterfall-template.json — importable 18-node starter waterfall