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ToolWren

117 free, private, client-side tools — encoders, decoders, converters, generators and calculators including Base64, JWT, QR codes, JSON, hashes, timestamps, regex and more. Nothing is uploaded.

100% client-side · nothing is uploaded · works offline
Encoding →

🔤Base64

Encode text to Base64 or decode Base64 to text instantly in your browser. UTF-8 safe, private, no upload.

3️⃣Base32

Encode text to Base32 or decode a Base32 string back to text (RFC 4648). UTF-8 safe, private, runs in your browser.

🔗URL

Percent-encode text for safe use in URLs, or decode an encoded URL component. Runs entirely in your browser.

🔢Hex

Convert text to hexadecimal bytes or hex back to text. UTF-8 aware, runs entirely in your browser.

💾Binary

Convert text to 8-bit binary or binary back to text. UTF-8 aware. Runs entirely in your browser, no upload.

📄HTML Entities

Escape HTML special characters or unescape entities back to text. Prevent XSS and display code safely. Runs in your browser.

🌐Unicode

Convert text to \uXXXX Unicode escape sequences used in JSON and source code, or decode them back. Runs in your browser.

🔡Backslash Escape

Escape or unescape backslash sequences (\n, \t, quotes) in strings. Free online escape tool.

📐Byte Counter

Count how many bytes a string uses in UTF-8, plus characters and UTF-16 units. Free online byte counter.

🔠ASCII Table

Look up ASCII codes — convert characters to decimal/hex codes and back, with a full printable table. Free online.

Tokens →

🔑JWT

Decode a JSON Web Token to inspect its header and payload, with an automatic expiry check. Private — nothing is uploaded.

🔏JWT Generator

Create and sign a JSON Web Token (HS256/384/512) in your browser using the Web Crypto API. Private, nothing uploaded.

🛰️CoAP

Decode a CoAP binary message from hex: header, type, code, message ID, token, options and payload. RFC 7252, runs in your browser.

📦CBOR

Decode a CBOR binary payload from hex into readable JSON. Ideal for IoT, COSE and CoAP debugging. Runs in your browser.

🛡️Basic Auth

Generate or decode an HTTP Basic Authentication header from a username and password. Runs in your browser — credentials never leave your device.

🚦HTTP Status

Look up any HTTP status code (200, 301, 404, 429, 500…) with its class and a plain-English description. Free, instant, in your browser.

Data →

⏱️Timestamp

Convert Unix epoch timestamps to human-readable dates and dates back to epoch. Auto-detects seconds vs milliseconds. Runs in your browser.

{ }JSON

Beautify, validate and minify JSON in your browser. Pretty-print with indentation or compress to one line. Private, no upload.

🗂️CSV ⇄ JSON

Convert a CSV table to a JSON array of objects, or JSON back to CSV. Handles quoted fields. Runs entirely in your browser.

🧾YAML ⇄ JSON

Convert YAML to JSON or JSON to YAML in your browser. Supports maps, lists and scalars. Private, no upload.

🌀cURL Converter

Convert a cURL command into ready-to-run Python (requests), JavaScript (fetch) or Node.js code. Runs in your browser.

#️⃣Hash

Generate MD5, SHA-1, SHA-256 and SHA-512 hashes of any text instantly in your browser. Private, no upload.

🆔UUID

Generate random UUID v4 and ULID identifiers in bulk with one-click copy. Cryptographically random, runs in your browser.

⏲️Cron

Translate a cron expression into plain English and preview the next scheduled run times. Free, runs in your browser.

🗄️SQL Formatter

Beautify and indent SQL queries with keywords on new lines for readability. Runs entirely in your browser.

📰Markdown

Convert Markdown to HTML — headings, bold, italic, links, lists and code. Free online Markdown converter.

🧼Strip HTML

Remove all HTML tags from text, leaving just the readable content. Free online HTML stripper.

💳Luhn Check

Check whether a number passes the Luhn checksum used by credit cards and IMEIs. Free online Luhn validator.

🧰JSON ⇄ TOML

Convert JSON to TOML or TOML to JSON in your browser. Handles nested tables and arrays of tables — ideal for Shopify app config, Cargo and pyproject.toml. Private, no upload.

Converters →

📏Length

Convert length and distance between meters, kilometers, miles, feet, inches, yards and nautical miles. Free, runs in your browser.

⚖️Weight

Convert weight and mass between kilograms, grams, pounds, ounces, stones and tonnes. Free and accurate.

🌡️Temperature

Convert temperature between Celsius, Fahrenheit and Kelvin instantly. Free online temperature converter.

🧪Volume

Convert volume between liters, milliliters, US/UK gallons, cups, pints, quarts and fluid ounces. Free, in your browser.

🗺️Area

Convert area between square meters, square feet, acres, hectares and square miles. Free online area converter.

🏎️Speed

Convert speed between km/h, mph, meters per second, knots and feet per second. Free online speed converter.

💽Data Size

Convert digital storage between bytes, KB, MB, GB, TB and binary KiB/MiB/GiB. Free online data size converter.

📶Data Rate

Convert data transfer rates between bps, kbps, Mbps, Gbps and MB/s. Understand internet speeds and download rates.

🎈Pressure

Convert pressure between pascals, kPa, bar, psi, atmospheres and mmHg. Free online pressure converter.

⚡Energy

Convert energy between joules, calories, kilocalories, watt-hours, kWh and BTU. Free online energy converter.

🔌Power

Convert power between watts, kilowatts, megawatts, horsepower and BTU per hour. Free online power converter.

📐Angle

Convert angles between degrees, radians, gradians, turns, arcminutes and arcseconds. Free online angle converter.

〰️Frequency

Convert frequency between hertz, kilohertz, megahertz, gigahertz and RPM. Free online frequency converter.

⛽Fuel Economy

Convert fuel economy between US MPG, UK MPG, kilometers per liter and liters per 100km. Free online converter.

👟Shoe Size

Convert shoe sizes between US, UK and EU systems (approximate men's sizing). Free online shoe size converter.

🔢Number Base

Convert numbers between binary, octal, decimal and hexadecimal instantly. Free online base converter for programmers.

🏛️Roman Numerals

Convert between Arabic numbers and Roman numerals (1-3999). Free online Roman numeral converter.

🍳Cooking

Convert cooking measurements between cups, tablespoons, teaspoons, milliliters and fluid ounces. Free online cooking converter.

⌛Time Units

Convert time units between seconds, minutes, hours, days, weeks, months and years. Free online time converter.

📖Reading Time

Estimate reading and speaking time from a word count at average speeds. Free online reading time calculator.

Color →

🎨Color

Convert colors between HEX, RGB and HSL with a live swatch. Edit any field and the others update. Runs in your browser.

🖼️Palette

Extract the dominant color palette from any image as HEX codes. Processed locally in your browser — no upload.

🌗Contrast

Check the WCAG contrast ratio between text and background colors, with AA and AAA pass/fail grades. Free online contrast checker.

🎚️Gradient

Build a CSS linear or radial gradient between two colors and copy the ready-to-use code. Free online gradient generator.

🎛️Shades & Tints

Generate shades, tints and tones from any base color, each with a copyable HEX code. Free online color shade generator.

👁️Color Blindness

Preview how a color looks to people with the common types of color vision deficiency. Free online color blindness simulator.

🔴HEX to RGB

Convert a HEX color code to RGB and back, with optional alpha/opacity and ready-to-paste CSS. Free online HEX to RGB converter.

🏷️Color Name

Find the closest named CSS color to any HEX code, or look up the HEX value of a named color. Free online color name tool.

Generators →

📝Lorem Ipsum

Generate Lorem Ipsum placeholder text by paragraphs, sentences or words for mockups and designs. Free, in your browser.

🔳QR Code

Generate a QR code for any text, URL or Wi-Fi network in your browser and download it as PNG or SVG. Private, no upload.

🔐Password

Generate strong, random passwords with custom length and character sets. Cryptographically secure, runs in your browser.

🔑Passphrase

Generate memorable Diceware-style word passphrases that are strong yet easy to remember. Runs in your browser.

🎲Random Number

Generate random integers within a range, with an option for unique values. Free online random number generator.

🎲Dice

Roll virtual dice using standard notation like 2d6+3 or d20. Free online dice roller for tabletop games.

🪙Coin Flip

Flip a virtual coin once or many times and see the tally of heads and tails. Free online coin flipper.

🎯Random Picker

Shuffle a list or pick random items from it — for raffles, teams and decisions. Free online random picker.

🌈Random Color

Generate random colors as HEX codes for design inspiration and palettes. Free online random color generator.

Calculators →

📐Aspect Ratio

Keep an aspect ratio when resizing: enter the original size and one new dimension to get the other. Free, in your browser.

%Percentage

Calculate X% of Y, what percent X is of Y, and percentage increase or decrease between two numbers. Free online.

🎓GPA

Calculate your GPA from course grades and credit hours on the 4.0 scale. Add as many courses as you need. Free online.

🕐Hours

Calculate the hours and minutes between two times, minus breaks. Free online hours worked, time duration and time card calculator with decimal hours.

➗Fraction

Convert a fraction to a decimal and percentage instantly. Free online fraction to decimal calculator.

🧮Ratio

Solve a proportion A:B = C:D for the missing value. Free online ratio and proportion calculator.

🔬Scientific Notation

Convert numbers between standard decimal, scientific (E) notation and engineering notation. Free online scientific notation calculator.

📈Statistics

Calculate the mean (average), median, mode, range, sum and standard deviation of a list of numbers. Free online statistics calculator.

🧮Calculator

A free online calculator with standard and scientific modes: arithmetic, powers, roots, logarithms, trigonometry, factorials and memory. Full keyboard support, works in your browser, nothing uploaded.

Finance →

🏦Loan

Calculate monthly loan or mortgage payments, total interest and total cost from amount, rate and term. Free online.

🍽️Tip

Calculate the tip and split the bill between any number of people. Free online tip calculator.

🏷️Discount

Calculate the sale price and how much you save from an original price and discount percentage. Free online.

🧾VAT

Add or remove VAT or sales tax from a price at any rate. See net, tax and gross amounts. Free online.

📈Compound Interest

Project investment growth with compound interest and optional monthly contributions. Free online compound interest calculator.

💵Simple Interest

Calculate simple interest and the final amount from principal, rate and time. Free online simple interest calculator.

💼Salary

Convert a salary between hourly, daily, weekly, monthly and annual figures. Free online salary converter.

🚗Fuel Cost

Estimate the fuel cost of a trip from distance, efficiency and fuel price. Free online fuel cost calculator.

🏠Mortgage

Free mortgage calculator: work out your monthly repayment, total interest and total cost from the property price, deposit, interest rate and term, with optional property tax and insurance. Private and instant.

Health →

⚖️BMI

Calculate your Body Mass Index (BMI) in metric or imperial units and see the standard weight category. Free online.

🔥BMR

Estimate your Basal Metabolic Rate (BMR) and daily calorie needs with the Mifflin-St Jeor equation. Free online.

📊Body Fat

Estimate body fat percentage using the U.S. Navy circumference method. Free online body fat calculator.

🏃Pace

Calculate running pace per km and per mile, plus speed, from distance and time. Free online pace calculator.

😴Sleep

Find the best bedtimes or wake-up times based on 90-minute sleep cycles. Adjustable cycle length and fall-asleep time. Free sleep cycle calculator.

💧Water Intake

Estimate your recommended daily water intake from body weight and activity. Metric and imperial. Free online water calculator.

🔥Calories Burned

Estimate calories burned during exercise from the activity's MET value, your weight and duration. Free online calorie burn calculator.

Date & Time →

🎂Age

Calculate exact age in years, months and days from a birth date, plus total days and a next-birthday countdown.

📅Business Days

Count working days between two dates, excluding weekends and US federal or UK bank holidays. Free, in your browser.

💬Discord Timestamp

Generate Discord timestamp tags from any date with a live preview of every format (relative, short, long). Free online.

📆Date Add

Add or subtract days, weeks, months or years from a date. Free online date calculator.

🗓️Date Difference

Count the days, weeks, months and years between two dates. Free online date difference calculator.

⏳Countdown

See a live countdown to any future date and time, in days, hours, minutes and seconds. Free online.

🌍Time Zone

Convert a time from one time zone to another and compare a live world clock across major cities. Handles daylight saving automatically. Free, private, in your browser.

Text →

⚙️Regex Tester

Test a regular expression against sample text with live matches, flags and capture groups. Runs in your browser.

✍️Word Counter

Count words, characters, sentences and paragraphs with reading-time estimate, live as you type. Private, in your browser.

🔠Case Converter

Convert text between UPPER, lower, Title, Sentence, camelCase, PascalCase, snake_case, kebab-case and CONSTANT_CASE.

🔗Slug

Turn any title or sentence into a clean, URL-safe slug. Handles accents and lets you choose the separator.

🔍Text Diff

Compare two blocks of text line by line and highlight what was added, removed or changed. Runs in your browser.

🔄Reverse Text

Reverse text character by character instantly. Free online text reverser.

🧹Dedupe Lines

Remove duplicate lines from a list, keeping the first occurrence. Free online duplicate line remover.

🔤Sort Lines

Sort lines alphabetically (A-Z or Z-A), numerically, or reverse them, with dedupe. Free online line sorter.

📃Line Counter

Count the number of lines, non-empty lines and characters in text. Free online line counter.

✂️Whitespace

Trim each line and collapse repeated spaces and blank lines. Free online whitespace cleaner.

📻NATO Phonetic

Convert text to the NATO phonetic alphabet (Alpha, Bravo, Charlie). Free online NATO phonetic converter.

🙃Upside Down

Flip text upside down using special Unicode characters. Free online upside down text generator.

💬Leetspeak

Convert text to leetspeak (l33t), replacing letters with numbers and symbols. Free online leet converter.

📊Char Frequency

Count how often each character appears in text, sorted by frequency. Free online frequency counter.

Ciphers →

🔁ROT13

Apply the ROT13 letter-rotation cipher online. Symmetric — the same action encodes and decodes. Runs in your browser.

📡Morse

Translate text to Morse code or decode Morse back to text. Supports letters, digits and punctuation. Runs in your browser.

🏺Caesar Cipher

Encrypt or decrypt text with a Caesar shift cipher (any shift 0-25). Free online Caesar cipher tool.

🔃Atbash

Apply the Atbash cipher, mapping A to Z, B to Y and so on. Its own inverse. Free online Atbash tool.

🗝️Vigenère

Encrypt or decrypt text with the Vigenère keyword cipher. Free online Vigenère cipher tool.

What is ToolWren?

ToolWren is a free collection of 117 encoders, decoders, converters, generators and calculators that run entirely in your browser. Click any tool above to open its own page.

Private by design: every tool runs 100% client-side. Whatever you type or upload is processed in your browser and is never sent to, received by, or stored on any server — no uploads, no logging, no tracking of your input. The tools even keep working offline once a page has loaded.

Browse by category — Encoding, Tokens, Data, Converters, Color, Generators, Calculators, Finance, Health, Date & Time, Text, Ciphers — or pick a tool from the grid above. Each tool has its own page with a step-by-step how-to guide and FAQ.

New to any of these? Read our free guides & tutorials — plain-English explainers that link straight to the right tool.