Free SEO & Marketing Tools & Calculators
Browse 16+ free interactive seo & marketing calculators, estimators, and utilities. 100% free, private, and runs directly in your browser without signup.
Master Website Directory & Sitemap Hub
Clean, structured directory of all developer utilities and technical articles without AI slop.
Headline Analyzer — Score Your Headlines for Impact
Free headline analyzer: score any headline 0-100 for impact. Checks word balance (common, uncommon, emotional, power words), ideal length, sentiment and structure, with Google SERP, email and social previews. 100% client-side.
JSON-LD Event Generator
Free JSON-LD event schema generator — build Google-ready schema.org Event markup with dates, venue, tickets and organizer. Live preview, rich-result checklist, copy & download. 100% client-side.
JSON-LD Person Generator — Person Schema Markup
Generate JSON-LD markup for Persons. Free Person schema generator with live JSON-LD preview, Google checklist, copy and download.
Meta Tag Analyzer
Free online meta tag analyzer — paste HTML to audit title, meta description, Open Graph, Twitter Cards, canonical, robots, hreflang and more with a 0-100 SEO score, SERP previews and fix recommendations. 100% client-side.
Robots.txt Parser & Validator Online
Free online robots.txt checker, robots.txt validator, and robots.txt analyzer. Test robots.txt file, verify robots.txt syntax, generate robots.txt file for SEO.
Schema Generator
Schema Validator
SEO Meta & Title Length Checker
Real-time dual SERP simulator, pixel width analyzer, and SEO title and description length checker.
Google SERP Snippet Preview & Simulator
Free online Google SERP simulator to preview how web pages, title tags, and meta descriptions appear in Google search results on desktop and mobile.
XML Sitemap Generator — URL List to Valid Sitemap XML (Free)
Free XML sitemap generator: paste your URL list and get valid sitemap XML — auto-split sitemap index, image sitemap support, strict validation. 100% client-side; your URLs never leave the browser. Does not crawl websites.
Sitemap Parser — Extract URLs from XML Sitemap
Free online sitemap parser: paste XML sitemap or upload a .xml file to extract all URLs with lastmod, changefreq and priority. Export CSV or TXT. 100% client-side.
URL Slug Generator — SEO-Friendly Slugs
Free URL slug generator: turn titles into clean, SEO-friendly slugs with stop-word removal, max-length cap, prefix/suffix, bulk mode, and live URL preview. 100% client-side.
Advanced UTM Builder (Standalone)
Advanced UTM tracking link builder for campaigns: live validation, one-click presets, bulk mode, session history. 100% client-side.
UTM Parameter Parser (Standalone)
Extract UTM tracking tags from URLs, detect click IDs, validate tags, batch-parse links, and build campaign URLs. 100% client-side.
Word Counter — Free Online Word Counter & Writing Analyzer
Free online word counter with live word, character, sentence and paragraph counts, reading & speaking time, keyword density analyzer, Flesch Reading Ease, Flesch-Kincaid and Gunning Fog readability scores, writing goals and text tools. 100% private — runs in your browser.
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How to Use the Tools Directory
Every tool is a single interactive page: enter your inputs, get instant results, no account needed. Use the search box (shortcut: press /) to jump straight to a tool, or browse categories when you are exploring. Each card links to the tool's permanent URL, which you can bookmark or share.
Because all computation happens in your browser, the tools are fast, private, and free forever. If a result looks wrong, use the one-click report control on the tool page so it can be fixed.
Tool Categories at a Glance
| Category | What you will find | Example tasks |
|---|---|---|
| Developer | Encoders, formatters, regex, network tools | Format JSON, test regex, subnet a network |
| Finance | Tax, loans, salary, investing | Estimate tax brackets, amortize a loan |
| Home improvement | Estimators, measurements, materials | Size a wire, estimate paint or flooring |
| Health & fitness | Body metrics, nutrition, workouts | Track BMI, plan calories, score fitness tests |
| Math & science | Converters, geometry, statistics | Convert units, solve triangles |
| Text | Counters, sorters, generators | Count words, alphabetize a list |
| Color | Pickers, converters, checkers | Convert HEX to RGB, check contrast |
| Everyday life | Cooking, travel, automotive, pets | Convert recipes, plan fuel costs |
Popular Tasks and Where to Start
| I want to... | Start with | Why |
|---|---|---|
| Convert between number bases | Binary Converter | Step-by-step base conversion with charts |
| Validate and format data | JSON Formatter | Pretty-print and check JSON instantly |
| Count words for an essay | Word Counter | Words, characters, reading time |
| Check password strength | Password Strength Meter | Entropy-based strength scoring |
| Grade text readability | Readability Score | Flesch-Kincaid and grade levels |
| Audit color contrast | Accessibility Checker | WCAG contrast ratios in one click |
Tools Directory FAQ
What is the NRTechStudio tools directory?
It is a free catalog of more than 2,700 interactive web tools: calculators, converters, generators, and checkers for developers, finance, home improvement, health, education, and everyday tasks.
Are all the tools really free?
Yes. Every tool in the directory is free to use with no sign-up, no trial, and no paywall. They run entirely in your browser.
Do I need to create an account?
No. There are no accounts, logins, or subscriptions. Open a tool and use it immediately.
Is my data private when I use these tools?
Yes. The tools are 100% client-side: your inputs are processed by JavaScript in your own browser and never sent to a server.
How do I find the right tool?
Use the search box at the top of the directory (press / to focus it), or browse by category. Every tool card shows a short description of what it computes.
Do the tools work on mobile?
Yes. The directory and the tools use responsive layouts that adapt to phones, tablets, and desktops.
How many tools are there?
The directory holds more than 2,700 tools and grows regularly as new calculators and converters are published.
Can I request a new tool?
Yes. Each tool page has a report/feedback control you can use to request features or new tools; requests help prioritize what gets built next.
Are the tools accurate?
Calculators use published formulas and reference data (tax tables, NEC ampacity, standard conversions). Each tool page documents its method, and issues can be reported in one click for a fix.
Do tools work offline?
Once a tool page has loaded, most tools keep working without a connection because the logic is client-side JavaScript. The directory search needs the page loaded first.
What categories are covered?
Developer utilities, finance and tax, home improvement, health and fitness, math and science, text tools, color tools, networking, education, and everyday life calculators, among others.
Can I bookmark or share a tool?
Yes. Every tool has its own permanent URL under nrtechstudio.com/tools/, which you can bookmark or share directly.
Is there an API for these tools?
The tools are interactive web pages, not API endpoints. The underlying math is plain JavaScript you can inspect in the page source.
Why do some tools show ratings?
Ratings aggregate user feedback to surface the most trusted tools and flag pages that need fixes or better explanations.
How often are new tools added?
New tools are published on a continuous pipeline, prioritized by measured search demand and by user requests from the feedback controls.
Who builds these tools?
NRTechStudio, an independent tools studio focused on free, private, client-side utilities that respect user privacy.