Free Online Tools for Everything You Do
Browse 2,706+ free interactive tools - home improvement estimators, pet calculators, cooking converters, automotive tools, finance planners, fitness calculators, developer utilities and more. No sign-up. 100% private. Runs entirely in your browser.
How to Change a Mixed Fraction into a Decimal – Fraction Calculator
Free fraction to decimal calculator with equivalent fractions, mixed number to decimal, long division method, fraction quiz, and step-by-step explanations.
Median Mode and Range Calculator & Statistics Guide
Interactive statistical calculator for median, mode, mean, range, median deviation, and percentile breakdown.
Flesch Reading Ease & Word Readability Calculator
Free online Flesch reading ease calculator and word readability statistics analyzer. Calculate reading level of text and learn how to find readability in word.
How to Find the Diameter of a Circle & Geometry Suite
Interactive circle geometry solver to find diameter, radius, area, circumference in terms of pi, and square footage with dynamic SVG visualizer.
How to Find the Greatest Common Factor
Interactive greatest common factor calculator, Euclidean algorithm solver, prime factorization breakdown, and step-by-step arithmetic guide.
How to Find the Median of 2 Numbers – Mean Median Mode Calculator
Interactive statistics calculator covering mean, median, mode, range, and standard deviation with step-by-step explanations.
HP to Amps Calculator — Horsepower to Amperage (DC, Single-Phase & 3-Phase)
Free HP to amps calculator: convert motor horsepower to full-load amps for DC, single-phase and three-phase motors with efficiency & power factor. Reverse amps-to-HP mode, NEC FLA table, breaker & wire size hints. 100% client-side.
HP to kW Converter - Horsepower to Kilowatts
Free HP to kW converter: convert mechanical horsepower to kilowatts, metric PS, watts and back. Exact definitions (1 hp = 0.745699872 kW, 1 PS = 0.73549875 kW), quick tables, EV, engine and AC examples.
India HRA (House Rent Allowance) Exemption Calculator — Free Calculation
Free India HRA exemption calculator: compute the 3 Section 10(13A) components, compare metro vs non-metro cities, find minimum rent from an exemption target, and estimate taxable HRA.
HTML Anchor & OnClick Link Generator
Interactive HTML anchor generator, href builder, and onclick JavaScript event tester. Test live link behavior and copy clean code.
HSA vs FSA Calculator — 5-Year Comparison, 2026 IRS Limits & Forfeiture Risk (Free)
Free HSA vs FSA calculator: 5-year net-value comparison with 2026 IRS limits, rollover vs forfeiture simulator, triple-tax-advantage explainer, tax-savings breakdown and a clear verdict. 100% private — runs entirely in your browser.
Hsl To Hex
Convert HSL colors to Hexadecimal format.
HSL to RGB Converter — Convert HSL to RGB + HEX
Free HSL to RGB converter: enter hue (0-360), saturation and lightness (0-100%) to get RGB, HEX and rgb() instantly, with a live color preview and the full formula breakdown. 100% client-side.
HSV to Hex Converter
Enterprise-grade interactive HSV to Hex color converter, Hex code to HSV reverse calculator, and color space harmony suite with 100% SEMrush keyword optimization.
Htaccess Redirect Generator — 301/302/307 Redirects, RedirectMatch & RewriteRule
Free online htaccess redirect generator: 301/302/307/308 rules, RedirectMatch regex builder, www to non-www, HTTP to HTTPS and trailing-slash canonicalization, bulk rules, redirect loop validation. 100% client-side.
Universal HTML Converter & Cleaner
Interactive HTML converter suite to convert HTML to Excel, HTML to Word, text to HTML, link to HTML, and clean HTML code online.
HTML Entity Encoder & Decoder - Escape/Unescape HTML Online
Free HTML entity encoder & decoder: convert special characters to named, decimal or hex HTML entities, decode entities back, with live mode and a click-to-insert entity reference table. 100% client-side.
HTML Entity Decoder — Decode HTML Entities to Text Online
Free one-way HTML entity decoder: turn named, decimal & hex HTML entities into characters in your browser. Per-entity mapping, honest invalid-entity errors, searchable 2,231-entity reference.
HTML Entity Encoder & Decoder
Standalone professional HTML entity encode and decode developer tool. Encode special characters to HTML entities or decode HTML string back to raw text. Supports named, decimal, and hexadecimal entities.
HTML Link Generator & Hyperlink Maker
Standalone professional HTML link generator, hyperlink maker, and URL link generator. Create a href tags easily, generate HTML anchor tags online, and build SEO-safe website links with zero AI slop.
Free Online HTML Linter — Check HTML Errors, Accessibility & Best Practices
Free online HTML linter: find missing alt text, duplicate IDs, deprecated tags, heading skips and 29 rules line by line. Private, in-browser, no signup.
HTML List Generator — Convert Text to UL, OL & DL
Free HTML list generator: convert text to <ul>, <ol> or <dl> markup with nested lists, custom bullets, numbering styles, start/reversed attributes, live preview, copy & download. 100% client-side.
Html Minifier
Minify HTML code to reduce file size.
HTML Sanitize Tester — Test HTML Sanitization Online (Free)
Test your HTML sanitizer online: paste markup, see which tags survive an allowlist filter — script, on*, javascript: URLs stripped. Free tool.
HTML Tag Stripper — Remove HTML Tags Online (Free)
Free HTML tag stripper: paste markup, get clean plain text. Script & style removed, entities decoded, breaks preserved. 100% client-side.
Html Table Div
Convert <table> tags to CSS Grid <div> layouts.
HTML Table Generator — Free Online HTML Table Code Builder
Free HTML table generator: build tables in a spreadsheet-like grid, style them, and copy clean HTML, Bootstrap, Tailwind, or Markdown code. 100% client-side.
Html Table To Csv
Extract HTML <table> elements into CSV.
HTML to BBCode Converter
Free online HTML to BBCode converter — paste HTML markup and get forum-ready BBCode for phpBB, vBulletin, XenForo, SMF and MyBB with live preview. 100% client-side.
HTML to Markdown Converter
Free bidirectional HTML to Markdown converter. Convert HTML to Markdown online and Markdown to HTML with live preview, tables, code fences, copy and download. 100% client-side.
HTTP Headers Generator (Standalone)
Generate HTTP response headers online: HSTS, CSP, X-Frame-Options, Referrer-Policy, Permissions-Policy, caching and CORS with paste-ready output for Apache, Nginx and Express. 100% client-side.
HTTP Headers Parser (Standalone)
Parse raw HTTP headers into JSON, an explained table, validation and security analysis. 100% client-side.
HTTP Status Lookup — Every HTTP Status Code, Meaning & Fix
Free HTTP status code lookup: search 55+ HTTP status codes (200, 301, 404, 500…) by code or phrase, filter by category, see when each code happens, example scenarios and how to fix error codes. 100% client-side.
Hubble’s Law Calculator (v = H₀ × d) — Free, Client-Side
Hubble’s law calculator: compute recession velocity v, distance d, or the Hubble constant H₀. Planck 2018 & SH0ES presets, Hubble time tᴴ = 1/H₀, and redshift approximation.
Humidifier Size Calculator — Whole-House & Room GPD Sizer
What size humidifier do I need? Calculate gallons-per-day output for whole-house & portable humidifiers by sq ft, ceiling height & home tightness.
HVAC Repair vs Replace Calculator — $5,000 Rule, 10-Year Cost & Quote Checker | nrtechstudio.com
Free HVAC repair vs replace calculator: the $5,000 rule, age + SEER + repair-cost decision engine, 10-year total cost comparison, energy savings estimator, R-22 refrigerant factor, and contractor quote checker with 2026 US cost ranges. 100% private — runs in your browser.
Hydraulic Jump Calculator — Conjugate Depth via Froude
Free hydraulic jump calculator: compute conjugate depth y₂ from upstream Froude number Fr₁, energy loss ΔE, efficiency, jump length, and jump-type classification (undular–strong).
Hydraulic Radius Calculator — R = A/P (6 Channel Shapes + Depth Solver)
Free hydraulic radius calculator: compute R = A/P for rectangular, trapezoidal, triangular, full circular, partially filled circular, and semicircular channels, with depth-from-R solver and hydraulic depth A/T.
Hydrostatic Pressure Calculator (P = ρgh) - Solve, Convert Units, Force on Surface
Free hydrostatic pressure calculator: solve P = ρgh for pressure, density, gravity, or depth. Fluid presets (water, seawater, oil, mercury, glycerin), 7 pressure units, and force on a submerged surfac
Hydroxychloroquine Dose Calculator by Weight | HCQ Max Dose (AAO 5 mg/kg)
Educational hydroxychloroquine dose calculator: estimates the AAO 2016 ophthalmology safety ceiling of 5 mg/kg/day of actual body weight, checks a current dose against it, and shows 200 mg tablet schedules plus eye-screening context. Not medical advice.
Hypergeometric Distribution Calculator — P(X=k), CDF, Mean, Variance
Free hypergeometric distribution calculator: P(X=k), P(X≤k), P(X≥k), mean and variance for sampling without replacement. Card, lottery and QC sampling examples, PMF chart and table.
Hyperlink in WhatsApp Web & Message Link Generator
Interactive tool to create WhatsApp message links, click-to-chat hyperlinks for WhatsApp Web, and pre-filled message URLs.
Hypotenuse Calculator — Pythagorean Theorem Solver
Free hypotenuse calculator: solve any side of a right triangle with the Pythagorean theorem. Three modes (legs to hypotenuse, hypotenuse to leg), Pythagorean triple checker, length unit converter, and a live triangle diagram.
Hz, kHz, MHz, GHz Frequency Converter
Interactive frequency converter across Hertz, Kilohertz, Megahertz, and Gigahertz with RF spectrum band diagnostics.
Hz to Radians Converter — Hz ↔ rad/s, RPM, deg/s Calculator | nrtechstudio
Free Hz to rad/s converter: convert hertz to radians per second (ω = 2πf) and back, plus RPM, rev/s, degrees/second, period, motor shaft speed, tip speed, and waveform angular frequency. 100% client-side.
Hz to Seconds & Period Calculator
Interactive frequency to period converter, calculating hz to seconds, angular frequency in rad/s, and wave periods.
IBAN Validator — Free IBAN Checker, Calculator & Generator (89 Countries)
Free IBAN validator suite: check any IBAN (MOD-97 + per-country format), parse BBAN structure for 89 countries, generate test IBANs, calculate IBAN from domestic account numbers, bulk-validate lists. 100% client-side — nothing leaves your browser.
Ibuprofen Dosage Calculator (200 mg Tablets & Children's Weight-Based)
Educational ibuprofen (Advil/Motrin) dose estimator: adult 200 mg tablet schedule with 24-hour counter, children's weight-based dose (10 mg/kg, suspen
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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.