Launching today
List Detective: Free Email List Checker
Find out what's wrong with your email list. 100% Free.
17 followers
Find out what's wrong with your email list. 100% Free.
17 followers
Uncover hidden problems in your email list — instantly and for free. Up to 100,000 addresses — runs entirely in your browser, nothing is sent to a server. Built for email marketers who care about deliverability and sender reputation. Try now with the sample data available on the site.
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@mumme_fanaei A genuinely free list checker with no bait-and-switch is rarer than it should be, so this is a nice one to see on the front page.
One gap I noticed: there's no demo video on your launch yet, and showing exactly what's wrong with a list is the kind of thing that's far more convincing when people watch it happen. So I made you a short one, free and yours: https://www.youtube.com/watch?v=vw9ngx_4yHY.
It's whitelabel, branded only to List Detective, no strings attached. Your launch is still editable — drop it into the gallery whenever you like.
Made with https://foxplug.com. Wishing you a strong day up there.
@saulfleischman Thank you Saul — really appreciate the gesture! 🙏 The video doesn't quite capture the full flow but the thought is much appreciated. Agree on the demo video point — it's on the list.
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@mumme_fanaei Yesm that's because we do it just what we can get from your landing page. You can make one by clicking through the site from a logged in state on you site from our landing page, "record walkthrough"
Congratulations on the launch! I tried it on your site and like how it works. I find this genuinely useful, especially the GDPR angle since nothing leaves the browser. One question: you mention up to 100k addresses -- does that run comfortably on an average laptop, or is there a point where browser performance starts to degrade?
@alieksia Thank you Anastasiia — really glad the GDPR angle resonated, it was the core reason for building it this way.
On the 100k question: in testing it handles 100,000 addresses comfortably on a modern laptop — the processing is pure JavaScript string matching with no heavy computation. The one caveat is the results table, which only renders the first 500 rows in the browser for performance reasons. The full list is always available via the download buttons regardless of size.
On older or lower-powered devices there may be a brief pause on very large lists — which is why the button shows "Checking…" during processing so you know it's working. If anyone hits issues I would love to hear about it.
@mumme_fanaei Thank you, that's a clear answer :) Makes sense, and I'll let you know if I run into anything.
How does it actually catch things like role-based or disposable addresses, and does it check MX records live or just match against a static list?
@kbra84zm Great question Kübra, here's exactly how it works under the hood:
Role-based addresses are caught by matching the local part (everything before the @) against a list of 40+ known role prefixes... info, admin, noreply, support, billing, marketing and so on.
Disposable domains are checked against a built-in list of 300+ known services (Mailinator, YopMail, Guerrilla Mail etc), plus a live feed from a community-maintained GitHub repository of 7,800+ disposable domains that loads in the background when you open the tool.
No MX record checking — that requires a server-side call which would mean your addresses leaving the browser, which defeats the whole privacy purpose. What we catch is structural: format validity, known bad domains, typos, suspicious TLDs and non-ASCII characters. For existence verification (does this mailbox actually exist right now) you'd need a dedicated verification service.
How does it actually catch things like role-based addresses or temporary inboxes, and is it checking against a maintained blocklist or just syntax rules?
@ersinfjap Hi Ersin, Kübra asked almost the same thing just above — please see my answer there for the full breakdown! Short version: static lists for role prefixes, a live-updated community blocklist for disposable domains, and pattern matching for everything else. No MX checks... keeping it server-free is the whole point.
Being able to flag role-based addresses like info@ or support@ would be a nice addition since those often cause more bounces than personal inboxes.
@demet44834 Great news, Demet! List Detective already flags role-based addresses! info@, support@, admin@, noreply@ and 37 other role-based prefixes are all caught automatically. Try it with the sample data on the site to see it in action.
The "your list never leaves your device" angle is underrated. Every email marketer I've talked to has done the mental gymnastics of "we're technically leaking our subscriber list to clean it, but the tool promises they'll delete it." Browser-based removes the promise from the equation entirely.
Been running my own cold email prep for the last month (9 mailboxes across 3 domains, all warmed) and the pattern I keep seeing: teams verify their list once at import, but a 6-month-old verified list is not a verified list anymore. Emails go stale, roles change, companies fold. The list you cleaned in January is not the list you're sending to in July.
To your v2 question, the check I keep wanting is company-level status detection. Not just "is this email valid" but "is this company still active." A valid inbox at a shut-down company still bounces, just with a different error signature. Distinguishing "person left" from "company gone" would be the deliverability signal most tools don't surface.
Also the disposable domain check is a category that's evolving faster than most check tools track. New disposable providers spin up weekly. Curious how you handle keeping that list fresh without needing constant manual maintenance.
I`m not an email marketer, but interested in the topic and I really love the way you organised FAQ section on the website - very thoughtful and informative! Congratulations on launch!
@julia_shtogren Thank you Julia, that genuinely means a lot! The FAQ was one of those sections that kept growing as I thought through every question a marketer might have, including the uncomfortable ones like "why didn't it catch this disposable address?" Glad it came across as thoughtful rather than just box-ticking.