HomeTools
Free online tools for marketing, SEO and product teams
Answer the everyday questions of marketers, SEO specialists, product managers and designers in a minute: is the test significant, how fast does CAC pay back, how will the snippet look in Google, does the text pass WCAG contrast. Pick a collection by job or scan the full list below — all tools are free, need no sign-up and keep your data in the browser.
Pick a toolkit for your job
Every collection lists its tools with the question each one answers, the use cases and an FAQ.
Marketing
Tracked links, previews for search, social and email, and the math of CAC, LTV and virality.
Tools: 13Open →SEO
Snippet and social previews, robots.txt and hreflang generators, readability checks.
Tools: 7Open →Product management
Prioritize the roadmap, measure feature adoption and time to value, score user feedback.
Tools: 13Open →Product analytics
Funnel, activation, retention and revenue metrics with formulas and benchmarks.
Tools: 9Open →Growth
Unit economics, virality, acquisition links and conversion from trial to paid.
Tools: 13Open →A/B testing
Sample size, significance, Bayesian probability and choosing what to test.
Tools: 6Open →UX research
Survey sample size and scoring for NPS, CSAT, CES, SUS and Kano surveys.
Tools: 8Open →Product design
WCAG contrast, accessible palettes, type scales and onboarding UI checks.
Tools: 7Open →UX writing
Tooltip copy, readability, reading time, email subjects and search snippets.
Tools: 5Open →All free tools and what they answer
Every tool opens in the browser: no sign-up, no install, nothing sent to a server.
MarketingOpen the collection →
- UTM builder
How do I build consistent UTM links for every campaign and channel?
- UTM QR code generator
Which booth, flyer or poster brought visitors — and how do I tag a QR code for each one?
- QR code generator
How do I make a QR code for a link, Wi-Fi or contact that never expires?
SEOOpen the collection →
- SERP snippet preview
How will the title and description look in Google, and will they be cut off?
- Open Graph generator
Which Open Graph tags does the page need, and how will the link preview look?
- robots.txt generator and tester
Which robots.txt rules block or allow this URL for a given crawler?
- hreflang generator
Which hreflang tags connect the language versions of a page?
Product managementOpen the collection →
- RICE & ICE prioritization calculator
Which backlog items should go first by RICE or ICE score?
- Kano model survey analyzer
Which features are must-haves, performance features or delighters for users?
- Feature adoption calculator
How many active users actually adopt a feature, and how fast?
- CSAT & CES calculator
What are the CSAT and Customer Effort Score of these survey results?
- Time to value calculator
How long do new users take to reach the first value, and where do they drop off?
- Eisenhower matrix
What do I do now, what gets a date, what gets dropped — and do the first ones even fit this week?
- SWOT analysis with a TOWS matrix
What are the strengths, weaknesses, opportunities and threats — and which strategies follow from crossing them?
Product analyticsOpen the collection →
- Funnel conversion calculator
Where do users drop off between steps, and which step is worth fixing first?
- Activation revenue calculator
How much revenue does a lift in activation rate bring?
- Retention calculator
How many users stay after day 1, 7 and 30, and what does the curve say?
- LTV and CAC calculator
Does a customer earn back what it cost to acquire them?
GrowthOpen the collection →
- CAC payback period calculator
How many months until a new customer pays back its acquisition cost?
- SaaS quick ratio calculator
Is MRR growth efficient, or is churn eating the new revenue?
- Viral coefficient (K-factor) calculator
Does each user bring enough new users for viral growth?
- Trial-to-paid conversion calculator
How much revenue does a better trial-to-paid conversion add?
- Email subject line preview
Will the subject line and preheader fit in the inbox on mobile and desktop?
A/B testingOpen the collection →
- A/B test calculator
Is the difference between A and B significant, and how many users does the test need?
- Sample ratio mismatch calculator
Did the experiment really split traffic the way it was configured to?
UX researchOpen the collection →
- Survey sample size calculator
How many responses does a survey need for a given margin of error?
- NPS, CSAT and CES calculator
What is the Net Promoter Score of these answers, with a confidence interval?
- Van Westendorp calculator
What price range do buyers accept, and where do the price sensitivity meter curves cross?
- Gabor–Granger analysis
At which price on the ladder does revenue peak, and how elastic is demand?
- NASA-TLX calculator
How heavy did this task feel, and which kind of demand made it heavy?
Product designOpen the collection →
- Color contrast checker
Does this text and background color pair pass WCAG AA or AAA?
- Accessible palette generator
How do I get an accessible color palette with contrast checked for every shade?
- Type scale & fluid type generator
Which font sizes make a consistent, fluid type scale?
- SUS calculator
What is the System Usability Scale score, and is the usability good?
- Tooltip & tour reading time
Do users have enough time to read a tooltip or tour step before it moves on?
UX writingOpen the collection →
- Tooltip copy checker
Is this tooltip short, clear and actionable enough?
- Readability checker
How hard is this text to read, and which sentences are too long?
How we build these tools
Formulas on the page
Every calculator documents its method and sources: the two-proportion z-test, the sample size formula, the beta distribution, Flesch reading ease. You can check any result by hand.
Runs on your machine
The code runs in your browser with no server calls. Funnels, revenue and tooltip copy stay on your computer.
The result lives in the URL
Inputs are saved in the page address. Copy the link and a teammate sees the same numbers and charts.
FAQ
Are the tools really free?
Yes. No sign-up, no limit on calculations. We build them because we use calculators like these ourselves when we measure onboarding in our own products.
Where does the data I enter go?
Nowhere. The calculations run as JavaScript in your browser; the server only delivers the page. Inputs are written to the page URL so you can share a result, so do not paste anything you would not share as a link.
Can I trust the numbers?
The statistical functions are covered by automated tests: normal and beta distribution values are checked against high-precision references, sample sizes against Evan Miller’s calculator, and the Bayesian probability to beat control against the closed-form formula and a Monte Carlo simulation. The formulas are printed on each tool page.
How is Clew related to these tools?
Clew is a product onboarding service: tours, tooltips, checklists and modals inside your web app. The calculators measure what onboarding changes — activation, funnel conversion and retention.
Which tools are best for marketers?
Start with the marketing collection: the UTM builder for tracked links, the SERP snippet and Open Graph previews for how pages look in search and social, the email subject line preview, and the CAC payback, LTV:CAC and trial-to-paid calculators for channel economics.
Which tools help with SEO?
The SEO collection covers the page level (SERP snippet preview, Open Graph generator, readability checker) and the technical level (robots.txt generator and tester, hreflang generator), plus the UTM builder for tracking traffic without breaking canonical URLs.
What can a product manager use here?
The product management collection has RICE and ICE prioritization, the Kano survey analyzer, feature adoption and time to value calculators, NPS, CSAT and CES scoring, and the A/B test calculator for checking whether a change really worked.
Why is one tool listed in several collections?
Collections follow jobs, not departments. A UTM builder is a marketing tool and a growth tool; NPS matters to research and to product management. Each tool has one home collection shown in its breadcrumb and appears wherever it answers a question.