Free Developer & Code Tools & Calculators
Browse 326+ free interactive developer & code calculators, estimators, and utilities. 100% free, private, and runs directly in your browser without signup.
50/30/20 Rule Calculator: Split Your Paycheck into Needs, Wants & Savings
Free 50/30/20 rule calculator: split monthly net income into 50% needs, 30% wants, and 20% savings. Includes a budget compliance check, custom ratios, and what-if scenarios.
A Body Shape Index (ABSI) Calculator — Free, Private
Free A Body Shape Index (ABSI) calculator: enter waist, height, weight, age and sex to get your ABSI score, age/sex-adjusted z-score vs the NHANES ref
A-a Gradient (AaDO2) Calculator + PaO2/FiO2 Ratio
Calculate the alveolar–arterial oxygen gradient (A-a gradient / AaDO2) from the alveolar gas equation: PAO2 = FiO2×(Patm−PH2O) − PaCO2/R. Includes age-based normal limits, PaO2/FiO2 ratio, Berlin ARDS criteria, and inverse FiO2 mode. Free educational tool.
Airport Code Finder — Search 9,051 IATA/ICAO Codes by City, Name or Code
Free online airport code finder: instantly search 9,051 airports by IATA code, ICAO code, name, city or country. Get coordinates, elevation, distance between airports, and airports near you. 100% client-side, no signup.
Apache Linter — Check .htaccess & httpd.conf Syntax Online
Free online Apache .htaccess and httpd.conf linter. Heuristic client-side checker: directive typos, RewriteRule flag validation, block balance, wrong-context directives, and risky settings. No uploads.
API Tester — Free Online REST Client
Test HTTP API endpoints in your browser: GET, POST, PUT, PATCH, DELETE, HEAD, OPTIONS with query params builder, headers, JSON body validation, response viewer and request history.
ASCII to Binary Converter — Text to Binary & Binary to Text (Free, UTF-8)
Free ASCII to binary converter: encode text to 8-bit binary and decode binary back to text. UTF-8 aware (é, 中, emoji), per-character bit visualizer, spacing & MSB/LSB options. 100% client-side — nothing uploaded.
ASCII to Hex Converter — Text to Hexadecimal Encoder & Decoder | nrtechstudio.com
Free ASCII to hex converter: encode text to hexadecimal (UTF-8) with uppercase/lowercase, 0x prefix and spacing options, decode hex back to text, per-character breakdown and hex-dump view. 100% client-side.
Atom Feed Generator — Create Atom 1.0 XML
Free Atom feed generator — create valid Atom 1.0 XML (RFC 4287) online with live preview, validation, and one-click download.
Attic Size Calculator: Standing Area, Code Checks, Insulation & Vent Sizing | nrtechstudio
Attic size calculator: standing area from roof pitch, habitable-code checks, egress window rules, insulation R-value, vent sizing and access sizing. F
Base64 to Image — Decode, View & Download Online
Free online Base64 to image decoder: paste a Base64 string or data URI, preview the image, detect its format and dimensions, download or copy it. 100% client-side.
Base64URL to Hex Converter
Free Base64URL to hex converter — decode URL-safe Base64 into
Base64URL to String Decoder
Decode Base64URL (RFC 4648 section 5) back to text: padding-optional input, per-quartet decode math, strict UTF-8 validation, JWT segment detection, batch mode.
Basement Size Calculator — Room, Code Checks & Material Estimates | nrtechstudio.com
Basement size calculator: room area, IRC ceiling-height and egress-window code checks, plus flooring, insulation, lighting and paint estimates.
Bash to PowerShell Converter — Heuristic Line-by-Line Mapping
Convert Bash scripts to PowerShell free: heuristic line-by-line mapping (echo, ls, grep, export, if, for, curl) with honest per-line MAPPED/UNMAPPED flags. 100% client-side.
BBCode to HTML Converter
Free online BBCode to HTML converter — paste forum BBCode from phpBB, vBulletin, XenForo or MyBB and get clean, XSS-safe HTML with live preview. 100% client-side.
BBCode to Markdown Converter
Free BBCode to Markdown converter — convert forum BBCode back to Markdown online with live preview. Bold, lists, quotes, code, tables, links and images for phpBB, vBulletin, MyBB, XenForo and SMF. 100% client-side.
Belt Size Calculator — Find Your Belt Size in Inches, CM & S/M/L
Free belt size calculator: belt size from waist or pants size, inches to cm converter, men's, women's and kids' belt size charts, and a guide on how to measure belt size.
Bencode Decoder — Decode BitTorrent Bencode to JSON Online
Free online bencode decoder: decode BitTorrent bencode strings to JSON with strict validation, tree view, and UTF-8/hex/base64 output.
Bencode Encoder — JSON to BitTorrent Bencode Online
Free online bencode encoder: convert JSON to BitTorrent bencode format with live encoding, tree view, and hex dump.
Best Software Development Company & Project Estimator
Interactive project cost estimator, enterprise custom software engineering architecture, and bespoke software agency guide.
BIN File Converter
Convert and inspect binary (.bin, .dat) files into Hex dumps, Base64, ASCII text, and C-array formats online.
Binary to Decimal Converter — Free Online with Place-Value Steps | nrtechstudio.com
Convert binary to decimal and decimal to binary free. Interactive place-value bead visualizer, step-by-step working, binary fractions, bit grouping. 100% private — runs entirely in your browser.
Binary to Hex Converter — Nibble Visualizer with Steps | nrtechstudio
Convert binary to hex and hex to binary with a live nibble visualizer, show-your-work steps, 0x prefix and byte-spacing options. Free, private, 100% client-side.
Binary to String Converter — Decode Binary to Text Online (UTF-8)
Free binary to string converter: decode 0/1 bits to text with per-byte breakdown, honest UTF-8 errors, and reverse text-to-binary. 100% client-side.
Border Radius Generator
Build custom border radius.
Bra Size Calculator — 5-Measurement Method, Sister Sizes & Fit Guide | nrtechstudio.com
Free bra size calculator using the modern 5-measurement method (no outdated +4 rule): band + cup in UK, US, EU & FR sizes, sister-size finder, fit troubleshooter, size converter and breast-shape style guide. 100% private, runs in your browser.
build.gradle Generator
Free online build.gradle generator - Groovy and Kotlin DSL build file builder with plugins, dependencies, repositories, presets and custom tasks.
cJSON Code Generator
Generate C/C++ parsing and serialization code using the DaveGamble cJSON library from any JSON payload.
Capital Gains Yield Calculator — Stock Price Return + Dividends
Compute capital gains yield (P1-P0)/P0, dividend yield, and total stock return. With visual breakdown and annualization from the holding period.
Cargo.toml Generator — Create & Make Rust Manifest Online
Free online Cargo.toml generator: package metadata, dependencies, features, target cfg, profiles and workspace for Rust projects.
Carport Size Calculator — Find the Right Carport Dimensions
Free carport size calculator with 7 modes: vehicles-to-size sizer, capacity checker, standard size charts, door clearance, height check and fit valida
Cat Benadryl Dosage Calculator by Weight — Diphenhydramine mg, mL & Tablet Guide
Free cat Benadryl dosage calculator: enter your cat
Free Citation Generator — APA 7th, MLA 9th & Chicago 17th | nrtechstudio.com
Free citation generator: create APA 7th, MLA 9th and Chicago 17th citations side-by-side for books, journal articles, websites, YouTube videos and newspapers. No signup, no ads, 100% private — everything runs in your browser.
Code Converters Master Hub
Interactive master directory and multi-language code conversion hub across JSON, SQL, TypeScript, Python, Go, and C.
Code Diff
Code Formatter
Code Translator
Coded Message Generator
High-performance secret message coder and decoder supporting Caesar, ROT13, Vigenere, Atbash, Binary, and Hex ciphers.
Color Shades Generator & Color Palettes Maker
Professional color palettes generator, tints and shades generator, perchance palette maker, material color palette generator, and CSS color pattern generator online.
Insurance Combined Ratio Calculator — Loss Ratio + Expense Ratio
Compute insurance combined ratio from loss ratio and expense ratio. Includes result interpretation, two-company comparator, and component breakdown. Educational estimate, not financial advice.
Comma Separator Converter
Interactive tool that converts newline column lists into comma-separated text, SQL IN clauses, and custom delimited strings.
Compare Word Documents – Text Diff & Similarity Checker
Compare word documents, how do you compare two word documents, compare documents, compare two files online, compare 2 files online, compare between two files, find difference, compare 2 text files, compare 2 documents, ai text compare, text similarity checker, compare the code, difference between two texts, compare code side by side, word comparison tool.
composer.json Generator
High-performance interactive PHP composer.json Generator, PSR-4 autoload architect, and package manifest synthesizer with 100% SEMrush keyword optimization.
Convert JS to String
Convert JavaScript objects, functions, and multiline JS code into properly escaped strings, JSON strings, or template literals.
Convert Text
Universal online text converter supporting case transformations, ASCII/Binary/Hex encoding, line cleaning, and slugification.
Cookie Parser (Standalone)
Parse raw HTTP cookie strings (document.cookie / Cookie: header) into JSON, a decoded table, validation and __Secure-/__Host- prefix analysis. 100% client-side.
Corn Yield Calculator — Estimate Bushels per Acre by Kernel Count | nrtechstudio.com
Free corn yield calculator: estimate bushels per acre by kernel count (yield component method) or ear weight, with moisture correction to 15.5%, tonnes-per-hectare conversion, multi-site averaging, and full show-your-work. 100% client-side — your data never leaves 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.