Free ToolsFree Cold Email Tools That Actually Fix Things.
25 tools for deliverability, DNS, copy and planning. Checkers and generators run in your browser with no limits; the AI writers run on Nova, the same AI inside InboxOne. No signup, ever.
Most popular
Email Deliverability Checker
One scan for SPF, DKIM, DMARC, MX and blacklists with a 0–100 domain score.
Open toolEmail Spam Words Checker
Paste your email, see every spam trigger highlighted and get a spam score.
Open toolCold Email Mailbox Calculator
How many mailboxes and domains do you need for your daily send volume?
Open toolAI Cold Email Generator
Describe your offer and audience; get a 3-step cold email sequence.
Open toolDomain & DNS CheckersDomain & DNS Checkers
Look up and validate the records that decide whether you land in the inbox.
Email Deliverability Checker
One scan for SPF, DKIM, DMARC, MX and blacklists with a 0–100 domain score.
Open toolSPF Record Checker
Look up a domain's SPF record, count DNS lookups and catch syntax errors.
Open toolDKIM Record Checker
Verify a DKIM selector, inspect the public key and check key length.
Open toolDMARC Record Checker
Fetch and grade a DMARC policy, tag by tag, with upgrade advice.
Open toolMX Record Lookup
See a domain's mail servers, priorities and which provider hosts its inbox.
Open toolEmail Blacklist Checker
Check a domain or IP against 15+ DNS blacklists including Spamhaus.
Open toolRecord & Asset GeneratorsRecord & Asset Generators
Build correct SPF, DMARC and DKIM records, signatures and links in seconds.
SPF Record Generator
Pick your email providers and get a valid SPF record ready to paste.
Open toolDMARC Record Generator
Build a DMARC policy with reporting, alignment and rollout advice.
Open toolDKIM Record Generator
Generate a 2048-bit DKIM key pair in your browser. Private key never leaves it.
Open toolEmail Signature Generator
Design a clean, deliverability-safe signature and copy it into Gmail or Outlook.
Open toolMailto Link Generator
Build a mailto link with subject, body, CC and BCC, properly encoded.
Open toolCopy & List ToolsCopy & List Tools
Test subject lines, catch spam triggers and clean up addresses before you send.
Email Spam Words Checker
Paste your email, see every spam trigger highlighted and get a spam score.
Open toolSubject Line Tester
Score a subject line on length, clarity, spam risk and mobile preview.
Open toolEmail Permutator
Generate every likely email format for a name and domain, then verify the MX.
Open toolEmail Address Checker
Validate syntax, MX records, disposable and role-based addresses in bulk.
Open toolCalculators & PlannersCalculators & Planners
Size your infrastructure, model ROI and plan warm-up before you buy a single mailbox.
Cold Email Mailbox Calculator
How many mailboxes and domains do you need for your daily send volume?
Open toolCold Email ROI Calculator
Model replies, meetings, deals and ROI from your outreach numbers.
Open toolEmail Warm-up Schedule Calculator
Generate a day-by-day warm-up ramp for new mailboxes.
Open toolSecondary Domain Generator
Generate brand-safe cold email domain variations and check availability.
Open toolAI Writing ToolsAI Writing Tools
Generate sequences, subject lines, spintax and personas with Nova, our cold email AI.
AI Cold Email Generator
Describe your offer and audience; get a 3-step cold email sequence.
Open toolAI Subject Line Generator
Ten subject lines in five styles, scored for length and spam risk.
Open toolAI Cold Email Analyzer
Paste your email and get a scored teardown plus a rewritten version.
Open toolAI Spintax Generator
Turn any email into natural spintax and preview random variations.
Open toolAI Buyer Persona Generator
Build an ideal customer profile with pains, triggers and targeting filters.
Open toolAI Follow-up Email Generator
Paste your first email and get three follow-ups that add value, not pressure.
Open toolClient-side, no limits
DNS lookups go straight from your browser to Cloudflare and Google resolvers. Check 1 domain or 1,000. We never see them.
Built by infrastructure people
We provision and monitor Google Workspace mailboxes and domains for cold email every day. The checks mirror what our Shield monitoring runs 24/7.
Every issue links to the fix
A red X is useless without the record to paste. Each failing check points to the generator or guide that resolves it.
Need the fixes done for you? InboxOne sets up SPF, DKIM and DMARC automatically on every mailbox it provisions.
FAQQuestions about the free tools
Still stuck? Book a 30-minute deliverability call and we'll look at your setup together.
Yes. Every tool on this page is free, has no usage cap for the browser-based checkers and generators, and never asks for an email address or credit card. The AI tools have a fair-use limit per visitor so the service stays fast for everyone.
The DNS checkers, generators, calculators and copy tools run entirely in your browser using public DNS-over-HTTPS resolvers; nothing is sent to InboxOne. AI tools send only the text you submit to our AI bridge to generate a response, and we do not use it for training.
Most competitor tools are server-side and rate-limited to push you into a signup. Ours run client-side with no limits, check more blacklists, count SPF lookups recursively and link every issue to the exact fix. They are built by the team that provisions and monitors thousands of cold email mailboxes every day.
Run the Email Deliverability Checker on your sending domain first. It covers SPF, DKIM, DMARC, MX and blacklists in one pass and points you to the right generator for anything missing. Then size your setup with the Mailbox Calculator.
Absolutely. Tell us what would save you time at hello@inboxone.io or on a call and we will add it to the roadmap. Popular requests ship within a few weeks.
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