Free email deliverability & security tools
Sharp tools for the inbox: 45 checks for SPF, DKIM, DMARC, blocklists, TLS and more. Paste a domain, an email address, an IP or a link, and Check runs every test that fits it at once.
By using these tools you accept the Terms and the Privacy page.
Email deliverability
Authenticate your mail, keep it off blocklists and test what receivers see. 19 tools.
- Grade a domain's public email DNS setup A+ to F, with a fix list in priority order./score
Deliverability score
- Check a domain against the Gmail, Yahoo and Microsoft bulk sender rules, with a badge./sender-rules
Sender requirements checker
- Check an email address for typos, a working mail domain, disposable and role accounts./email-checker
Email address checker
- See which known data leaks an email address appears in, when, and what was exposed./leak
Data leak check
- Audit an SPF record against the 10-lookup limit, then build a correct one./spf
SPF checker
- Replace SPF includes with IP addresses to get under the 10-lookup limit./spf-flattener
SPF flattener
- Find and verify DKIM keys, or generate a new key pair in your browser./dkim
DKIM checker
- Check a DMARC policy and build one with a safe path to p=reject./dmarc
DMARC checker
- Open aggregate and failure reports (XML, ZIP, GZ) as plain tables, in your browser./dmarc-reader
DMARC report reader
- Validate the BIMI record, SVG Tiny PS logo and mark certificate./bimi
BIMI checker
- Turn an SVG logo into a BIMI-ready SVG Tiny PS file, in your browser./bimi-generator
BIMI logo converter
- Look up an IP or domain on verified DNS blocklists, with honest three-state results./blacklist
Blacklist check
- Spot temporary and throwaway email domains, one address or a whole list./disposable
Disposable email check
- Score an email's content and headers the way spam filters do./spam
Spam score
- Trace an email's hops and delays and read its SPF, DKIM, DMARC and spam filter verdicts./email-headers
Email header analyzer
- Send an email to our test address and get a full deliverability report back by email./email-test
Email test
- Paste a bounce message to see what the SMTP codes mean, who must act and how to fix it./bounce-explainer
Bounce explainer
- A day-by-day warm-up schedule for a new IP or domain, with the limits that pause it./warmup
IP and domain warm-up planner
- Verify TLSA records pinning certificates on a domain's mail servers./dane
DANE checker
Websites
Grade the transport, headers and links your visitors trust. 10 tools.
- Grade a server's protocols, cipher suites and certificate chain from the edge./tls
TLS checker
- Grade a site's HTTP security headers and cookies A+ to F./security
Security headers
- Follow a link through every redirect hop, safely, before you click it./trace
Redirect trace
- Fingerprint a site's CMS, framework, CDN, analytics and the SaaS its DNS reveals./tech
Tech stack detector
- See what any website can learn about your browser: fingerprint, WebRTC leak, GPC and IP./browser-privacy
Browser privacy test
- Find dead links on a page: same-site links fetched, external domains checked in DNS./links
Broken link checker
- Grade a site's readiness for AI agents, Level 0 to 5./ai-readiness
AI readiness
- See whether security vendors flag a domain for malware, phishing or spam./virustotal
VirusTotal check
- See whether Google lists a site or link for malware, phishing or unwanted software./safe-browsing
Google Safe Browsing check
- Real-user LCP, INP and CLS for a site, from Google's Chrome UX Report./core-web-vitals
Core Web Vitals check
Domains and networks
Who runs a domain, an address or a network, and how it is wired. 8 tools.
- A short AI profile of a domain or email address: what it is and whether it looks safe./ai-domain-intelligence
AI intelligence
- See the services a domain’s public DNS reveals: mail, senders, SaaS tools and hosting./domain
Domain analyzer
- Registrar, dates, name servers and status locks from the live WHOIS record./whois
WHOIS lookup
- Who owns an IP address or AS number, its announced prefixes and sample hostnames./asn
ASN lookup
- Check that an IP's PTR record resolves back to the same address (FCrDNS)./fcrdns
Reverse DNS check
- Network, broadcast, hosts and masks for IPv4 and IPv6, plus split, VLSM and summarize./subnet-calculator
Subnet calculator
- Your public IP, network and location, with proxy, VPN, Tor and WebRTC leak checks./showip
What's my IP
- Measure download, upload, ping and jitter to the nearest Cloudflare data center./speedtest
Speed test
Utilities
Small, private tools that run in your browser. 8 tools.
- Strong passwords and passphrases, generated locally and never sent./pw
Password generator
- Decode a JSON Web Token, check its dates and verify its signature, in your browser./jwt
JWT decoder
- Encode and decode Base64 and Base64URL text and files in your browser./base64
Base64 encoder
- SHA-256, SHA-512, SHA-1 and MD5 hashes and HMACs of text or files, in your browser./hash
Hash generator
- The full domain or email report as JSON, for scripts, Claude, ChatGPT and Cursor./developers
Free API and MCP server
- Random UUID v4 and time-ordered v7, in bulk, plus a decoder for any UUID./uuid
UUID generator
- QR codes for links, text, Wi-Fi and email, as PNG or SVG, made in your browser./qr-code
QR code generator
- Live BTC price, 24-hour range and chart, refreshing on its own./btc
Bitcoin price
Questions
What is zerobounce.ai?
A free set of tools for checking email authentication, deliverability, website security and networks, plus a few developer utilities. Each tool has its own page that explains what it checks and how to read the result.
Are the tools free, and do I need an account?
Every tool is free and works without an account or signup. Checks that ask other servers for data have per-minute limits per network, so the site stays fast for everyone.
What does Check on the home page do?
It works out whether you pasted a domain, an email address, an IP address or a link, and opens the full report, which runs every check that fits it at once: 20 for a domain, 14 for an email address, 12 for a link and 4 for an IP address.
How do I check my domain’s SPF, DKIM and DMARC?
Paste the domain above to run all three together, or use the SPF checker, DKIM checker and DMARC checker for the detail. The deliverability score grades the whole setup from A+ to F, with a fix list in priority order.
Who makes zerobounce.ai?
Hertza L.L.C., the company behind ZeroBounce, an email validation service. The tools are free, and links to ZeroBounce on this site go to our own paid service. The about page explains the rules every tool follows.
What happens to what I check?
Some tools run entirely in your browser; others ask zerobounce.ai’s server on Cloudflare and the services named on the privacy page to run the check. Nothing is sold or used for advertising.
Made by the people who validate email for a living
zerobounce.ai is made by Hertza L.L.C., the company behind ZeroBounce. ZeroBounce has validated more than 60 billion email addresses for 650,000+ customers in over 200 countries. These are the checks that work runs on, free for anyone. No accounts, no cookies, no trackers. More about the site.