Lemlist Usage Detector · Spot Companies Using Lemlist

Bulk-check which companies appear to run Lemlist for outreach. Each domain you paste comes back as one clear row: YES or NO — a strong buying / intent-style signal for sales, growth, and competitive research. Export CSV or JSON and plug into Sheets, your CRM, or sequencing tools.

The deliverable SDRs and growth teams care about is answer and answerDetail — not a DNS report.

This is not an official Lemlist product. It does not mean “this specific rep uses Lemlist” — only that the company’s domain shows public infrastructure consistent with Lemlist-style link tracking (custom tracking domain). Only use domains you’re allowed to check.

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Table of contents

• Why use this?
• How it works (short)
• Quick start on Apify
• What you get in the dataset
• Proxy and blocked HTTPS
• Input
• Output (dataset & stores)
• Example inputs
• Logs during a run
• Limits
• Support & contact
• Developers: local run, tests, deploy

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Why use this?

Without this	With this Actor
No scalable way to prioritize accounts that likely use Lemlist-style outbound	Automated YES/NO per company domain — intent-style signal for prospecting
Manual guesswork on tracking subdomains	One explainable line per prospect (answerDetail)
One-off checks	Hundreds of domains in one run (see Limits)

Who it’s for

• SDRs / AEs — enrich account lists, prioritize outreach, tailor messaging.
• Growth / RevOps — map the competitive landscape (“who runs this stack on their domain?”).
• Agencies — quick due diligence on prospect or client domains you’re entitled to review.

Reality check: YES = we saw a strong public signal on that domain (see below). It’s not a contract with Lemlist — use it as one signal among many.

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How it works (short)

1. You paste website URLs or domains (one per line); we normalize to the company domain (e.g. www.shop.com → shop.com).
2. We look for Lemlist-style tracking setup using public DNS and (by default) HTTPS, plus optional discovery from public SSL certificate logs.
3. Strong match → answer: YES; otherwise NO with a short reason. Technical options (extra proof rows, overview row, proxy, limits) → AGENTS.md.

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Quick start on Apify

1. Open the Actor in the Apify Console.
2. Paste domains — one per line (https://… or company.com).
3. Click Start.
4. Open Dataset → tab Results for answer / answerDetail, or All fields for full JSON.

If HTTPS fails from the cloud, set LEMLIST_RESIDENTIAL_PROXY=1 under Actor → Settings → Environment variables (see Proxy and blocked HTTPS).

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What you get in the dataset

Default: one row per company (apex_summary).

Field	For sales / ops
answer	YES or NO — treat as your Lemlist-usage signal for that domain.
answerDetail	One line you can read or forward (what matched, or how many checks ran).
apexDomain	Normalized company domain.
usesLemlist	Same as YES/NO for filters in Sheets or code.
evidenceHostname	When YES, where the signal showed up (if useful for your pitch).
inputSource	What you pasted.
checkedAt	Timestamp.

Optional: LEMLIST_RUN_OVERVIEW=1 — one extra row with totals + list of all domains. LEMLIST_INCLUDE_HOSTNAME_PROBES=1 — technical rows per subdomain (for audits). hostname_probe details: AGENTS.md.

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Proxy and blocked HTTPS

No proxy field in Input. By default, HTTPS runs direct from Apify.

If sites block datacenter IPs, set LEMLIST_RESIDENTIAL_PROXY=1 in Environment variables and ensure residential proxy is allowed on your plan. Locally: apify login.

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Input

Field	Required	Description
domains	Yes	Company website URL or domain — one per line.

Common environment variables (Actor → Settings → Environment variables):

Variable	When to use
LEMLIST_RESIDENTIAL_PROXY=1	HTTPS timeouts or blocks.
LEMLIST_SKIP_CT=1	Faster runs (fewer subdomains checked).
LEMLIST_DNS_ONLY=1	DNS-only (faster; fewer signals).
LEMLIST_INCLUDE_HOSTNAME_PROBES=1	Add technical proof rows.
LEMLIST_RUN_OVERVIEW=1	Add one aggregate summary row.

Power user / tuning: AGENTS.md.

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Output (dataset & stores)

• Default: apex_summary only — YES/NO per domain.
• Key-value store: RUN_LOG (progress text).
• Console: Results + All fields; Output tab → dataset API + RUN_LOG.

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Example inputs

{
  "domains": [
    "https://www.acme.com",
    "https://partner.io/blog",
    "otherbrand.com"
  ]
}

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Logs during a run

Short by default (summary + per-domain YES/NO line + final counts). LEMLIST_VERBOSE=1 for detail. The dataset is the source of truth.

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Limits

• 150 unique company domains per run; 2,500 planned checks max per run (usually less thanks to early exit).
• Certificate-based discovery ≠ every DNS name in the world.
• Compliance: only domains you may probe.

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Support & contact

Questions or issues? Corentin Robert.

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Developers: local run, tests, deploy

npm install
npm run apify:run
npm run test:unit && npm run test:smoke
npm test
apify push

Use npm run apify:run (or apify run --input-file=input.json) so local INPUT.json isn’t empty after purge.

Bump .actor/actor.json version (MAJOR.MINOR) when you publish. Maintainer notes: AGENTS.md.