Free tools are the most copied tactic in cold-email SEO. At least 15 of the 33 domains we crawled publish at least one checker, generator or calculator in their sitemaps, and most publish the same set: an SPF/DKIM/DMARC checker, a blacklist lookup, a spam-word checker, an email verifier and a few calculators. Each tool sits on a long landing page built to rank for "free X checker", and the result screen points back to the paid product.
The two market leaders are absent. Instantly's sitemap has 1,977 URLs and not one tool page. /tools, /free-tools and the obvious checker slugs return 404 (our probes, 5 Oct 2026). EmailBison has 67 URLs in total. Instantly's nearest equivalent is its 329-page /prompt/ library of "generator" prompts (Glossaries, template and prompt libraries). The free-tool SERPs belong to challengers.
Inventory by competitor
Counts are unique English tool pages found in each sitemap on 5 October 2026. Language copies are excluded, and so are blog posts about tools.
| Vendor | Tools | What they are |
|---|---|---|
| Salesforge | 29 (116 with de/fr/pt) | Spam checker, SPF/DKIM/DMARC checkers and generators, blacklist, SSL, WHOIS, ESP checker, verifier, finder, inbox-placement test, spintax, subject-line, cold-email and LinkedIn generators, "Roast my cold email" GPT, ROI and forecast calculators |
| Saleshandy | 21 + hub | Spam checker, "Spam Police", SPF/DKIM/DMARC, verifier, email/phone/company finders, inbox-placement test, "Sequence Score", spintax, five copy generators (CTA, sign-off, follow-up, gentle reminder, subject line), ROI and open-rate calculators |
| Smartlead | 21 + deliverability test | Spam checker, subject-line generator and analyser, grammar checker, copywriter, verifier, blacklist, SPF/DKIM/DMARC lookups and generators, CNAME, SSL, signature, four rate calculators (bounce, open, CTOR, spam-complaint) |
| SmartReach | 15 | DNS and authentication checkers and generators, spam-word checker, blacklist, SPF lookup-cost counter, four calculators |
| Hunter | ~13 | Email finder and verifier (the core product, free tier), deliverability checker, disposable-email checker, SPF/DMARC generators, subject-line tester, reverse lookup, warmup, outreach and TAM calculators |
| PlusVibe | 11 | Spam checker, SPF checker, verifier, finder, permutator, WHOIS, placement test, ROI, profit-margin and percentage calculators |
| Warmy | 11 | Deliverability test, template checker, SPF/DMARC generators, mailbox calculator, best-time-to-send, mobile preview |
| lemlist | 10 (40 with fr/de/es) | Deliverability setup checker, spam-words checker, email checker, finder, permutator, extractor, phone finder, cold-email and persona generators, signature |
| Snov.io | 10 + core finder/verifier | SPF/DKIM/DMARC, blacklist, CNAME, DNS, reverse IP, AI email writer, signature |
| 11x | 9 | BIMI, DKIM, DMARC, SPF, MX, blacklist, domain health, deliverability, "Google Postmaster health check" |
| MailReach | 6 (× 6 languages) | Spam test (also as an API), spam-score checker, SPF and DKIM checkers, deliverability test |
| Woodpecker | 6 + 6 signature variants | Infrastructure calculator, A/B-test calculator, SPF checker, blacklist, email preview, signature generator |
| Zapmail | 7 | Verifier, spam check, blacklist, SPF, CNAME, template generator, calculator |
| La Growth Machine | 5 + calculators | SPF, DKIM, DMARC and authentication checkers, pipeline-gap calculator |
| Klenty | 3 | Engagement audit, SDR calculator, cold-email generator |
| Instantly, EmailBison | 0 | — |
Clay's /tools/ family (237 English URLs) is something else: use-case landing pages such as "generate leads for hotels" that open a Clay table, not stand-alone tools. Treat it as Programmatic SEO.
Which tool types everyone ships
| Tool type | Vendors shipping it (of 15) | Note |
|---|---|---|
| SPF / DKIM / DMARC checker or generator | 14 | A DNS lookup; commodity |
| Inbox-placement / deliverability test | 9 | The only type with real cost (seed accounts) and real signal |
| Spam-word / content checker | 9 | Word-list matching; filters do not work that way (How filtering works) |
| Calculators (ROI, open rate, inbox count) | 10 | Cheap, and a natural place for an email capture |
| Email verifier | 8 | Usually a few free checks, then sign-up |
| AI copy generators | 7 | One LLM prompt per tool; Saleshandy alone ships five |
| Email finder | 7 | Free tier of a data product |
| Blacklist lookup | 7 | DNSBL queries |
| Signature generator | 6 | Pure link bait |
| Subject-line tester or generator | 4 | Hunter, Smartlead, Saleshandy, Salesforge |
The tool itself is the cheapest part of each page; the copy is the investment. Smartlead's spam checker runs about 2,300 words with FAQPage and SoftwareApplication markup. Hunter's subject-line tester runs 2,200 words with FAQPage and WebApplication. PlusVibe's spam checker runs 4,767 words. Saleshandy's verifier is the leanest at 751 words. Page lengths are our crawl's word counts, including chrome.
Does it work?
For one head query, "free cold email spam checker", our search tool (not a Google SERP; positions are indicative) returned Komo, a Reply.io blog post, Warmy's tool, Salesforge's French and English tool pages, Zeliq, MailReach's spam test and LeadHaste. A broader query surfaced Smartlead's spam checker and Supersend's tool. Salesforge's translated copies of the same tool rank side by side, which explains why it localises every tool into four languages.
The strongest evidence that tools pay is that every deliverability-infrastructure vendor builds them. MailReach, Warmy and Zapmail sell warmup, placement tests or mailboxes, and their checkers catch a buyer at the moment a deliverability problem shows up. Distribution makes the same point. MailReach also sells its spam test as an API, so the free tool doubles as a product demo.
No vendor publishes tool usage, sign-ups from tools or tool-page traffic. We did not run the tools, so we have not tested which ones gate results behind an email address or a sign-up. Semrush and Similarweb pages do not break traffic out by URL on their free tiers.
Distribution lists Instantly among vendors using free tools for SEO. Its sitemap and our URL probes found none on instantly.ai in October 2026. It may have run tools earlier, or may host them somewhere we did not find.
What is missing
Every tool above answers "is my DNS set up?" or "write me a line". None answers the questions an EU sender or a multi-client agency actually has:
- "Can I send this cold email to this person?" No vendor ships a country-by-country legality checker, even though the rules differ sharply: Germany requires prior consent even for B2B, the UK allows cold email to corporate subscribers with an opt-out, and France allows it when the message fits the recipient's job (EU/EEA country matrix, Germany, UK: PECR and DUAA 2025).
- "What does this reply mean?" No tool classifies a pasted reply (interested, not now, out of office with return date, unsubscribe, legal threat). The reply desk wedge does exactly this (The reply desk).
- "Am I compliant with Microsoft's bulk-sender rules?" 11x's "Google Postmaster health check" is the only provider-specific tool, and nobody covers Outlook (Microsoft rules: Outlook.com and Microsoft 365 limits).
- "Is my footer complete?" CAN-SPAM wants a postal address and an opt-out, and EU regimes want sender identification and an easy opt-out (United States: CAN-SPAM and state email laws, Cold email law: the jurisdiction matrix). Nobody ships a checker for it.
What this means for an entrant
- Do not build the 14th DMARC checker as a growth bet. The SERP is full and the tool is a DNS call. Ship SPF/DKIM/DMARC and blacklist checks only as onboarding utilities inside the product.
- Ship the EU legality checker first. The input is a recipient's country, B2B or B2C, the sender's country and whether there is an existing relationship. The output is a verdict, the legal basis and the footer text it requires. Its engine is the per-recipient country rule engine in The wedge, so the free tool is the product demo. Publish it in German, French and English, since Salesforge's side-by-side French and English results show localisation pays.
- Ship a free reply classifier. Paste a reply and get a category, the out-of-office return date and a suggested next step. It shows the The reply desk in ten seconds and targets agency operators, not students.
- Ask for the email at the moment of value. Show the verdict free, and ask for an address only for the PDF audit or a monitoring alert ("tell me when this domain lands on a blacklist"). Monitoring creates a reason to come back.
- Put 1,500+ words of real explanation on every tool page, with
FAQPagemarkup, the way Smartlead and Hunter do. Write the explanation from your own data, for example how often each check fails across your users' domains. That is copy competitors cannot reproduce. - Expose each tool through your API and MCP server too (API, webhooks and MCP). An assistant asked "is this email legal to send in Austria?" can call it, and a page alone cannot be called (llms.txt, pricing.md and AI crawlers).