Numeric Bases: Binary, Octal, Decimal and Hexadecimal
What a numeric base is and how binary, octal, decimal and hexadecimal work. Convert between bases with examples, an equivalence table and practical tips.
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How to Calculate the Difference Between Two Dates (Days, Weeks, Months and Business Days)
Calculate how many days are between two dates, how to count business days, when it is useful (deadlines, vacations, projects) and how to use our tool.
3 min readHow to Calculate the Exact Age in Years, Months and Days
Calculate your exact age in years, months, days, weeks and totals. How real date subtraction works, how leap years matter, and fun facts with examples.
3 min readHow to Convert Numbers to Words: A Quick Guide
Learn how to convert numbers to words for checks, invoices and contracts. See how the conversion works, the differences between Spanish and English, and the tool's limits.
3 min readCharacter and Word Counter: A Practical Text Guide
What a character and word counter counts: characters, words, letters, numbers and lines. Check Twitter, SMS and SEO limits and learn how to use it.
3 min readDate Format Converter: ISO, Unix, RFC, SQL and more
Convert dates between ISO 8601, RFC 2822/3339, Unix timestamp, SQL, EU/US format and custom. Standard tokens. Free.
3 min readRoman Numerals: How to Read and Convert Them (Table 1–3999)
Learn the rules to read and write Roman numerals, the 1–3999 table, the most common mistakes (IIII, VV) and how to convert instantly with our tool.
2 min readWhat is a Timestamp and How to Convert it to Date and Time
Learn what a Unix timestamp is, the difference between seconds and milliseconds, where it is used, and how to convert it to a readable date.
3 min readHow to Calculate Tips and Split the Bill Among Several People
Learn to calculate tips by country, how much to leave and how to split the bill fairly. Includes country table, formulas and common errors.
3 min readHow to Calculate Percentages: Complete Guide with Formulas and Examples
Learn to calculate percentages step by step. Formulas, quick example table and common errors when calculating discounts, taxes and percentage changes.
3 min readSimple Interest: Formula, Examples and Difference from Compound Interest
Learn to calculate simple interest step by step. Formula I = P × r × t, comparison with compound interest, real examples and when this type of interest is used.
3 min readWhat is Base64 and How to Encode and Decode Text
Base64 explained: what it is, what it is used for in APIs, email and URLs, how to encode and decode with our tool and why it is not an encryption system.
2 min readLorem Ipsum: What It Is, Origin, and How to Use It
Discover what lorem ipsum is, where it comes from, and how to use a filler text generator for your web designs, mockups, and templates effectively.
4 min readHow to Generate Secure and True Random Numbers
Learn how to generate secure random numbers with the Web Crypto API. Discover the difference between pseudo and cryptographic randomness and when each matters.
3 min readWhat Is a Barcode and How to Generate Your Own
Discover what a barcode is, how the Code 39 format works, and generate your own barcodes online for free in a compatible, widely supported format.
4 min readSleep Calculator: The Ideal Bedtime to Wake Up Rested
Find out what time to go to bed to wake up rested by completing full 90-minute sleep cycles. Plan your rest around your age and needs.
4 min readCalories Burned and Your Energy Expenditure: Calculate What You Burn Moving
Find out how many calories you burn walking, running, swimming or cycling using the MET method. Calculate your expenditure by weight, activity and duration.
3 min readLoan and Amortization Calculator: Payment, Schedule and Total
Calculate the monthly payment, full amortization schedule and total payable of any loan. French, German and American systems explained with examples.
3 min readInflation Calculator: Money Value Over Time
Calculate how inflation reduces purchasing power. Modes: future, past, cumulative. INE, ECB, BLS, ONS rates. Free.
4 min readJSON Formatter: Beautify, Minify, Validate and Sort
Format, minify, validate and sort JSON keys online. Detects syntax errors. Private: everything in your browser.
2 min readOnline JWT (JSON Web Token) Generator
Generate and decode JWTs signed with HS256/384/512. Customizable JSON header and payload. Local and secure.
2 min readOnline Regular Expression Tester (Regex)
Test and debug regex with flags, groups, highlighting and token-by-token explanation. Presets: email, URL, IPv4, DNI, IBAN. Free.
3 min readMacros Calculator: Carbs, Protein and Fat
Calculate your daily macros and calories based on goal and activity. Presets: balanced, high protein, low carb, keto. Free.
3 min readConvert Celsius to Fahrenheit: Formula, Table and Mental Tricks
Exact formula °F = °C × 9/5 + 32, reference table -40 to 100 °C, 'double and add 30' mental trick for approximations and when to use it.
2 min readConvert Kelvin to Celsius and Fahrenheit: Absolute Zero, Formulas and Uses
Kelvin is the absolute scale. Exact formulas K ↔ °C ↔ °F, table -273 to 1000 K, mental trick and uses in science, lighting (color temp) and cryogenics.
3 min readConvert Kilometers to Miles: Formula, Table and Quick Reference
Exact formula 1 km = 0.621371 mi, table 1–200 km, mental trick 'divide by 1.6' and when to use it. Includes nautical miles and yards.
2 min readConvert Pounds to Kilograms: Formula, Table and Mental Trick for Weight
Exact formula 1 lb = 0.45359237 kg, table 1–300 lbs, mental trick 'divide by 2.2' and body weight, luggage and gym references.
3 min readConvert Liters to Gallons: US, UK, Table and Consumption References
Difference between US gallon (3.785 L) and UK (4.546 L), exact formulas, table 1–200 L, mental trick and references: car tank, fuel economy, drinks, irrigation.
3 min readConvert Euros to Dollars (EUR/USD): Rates, Fees and Best Timing
How the EUR/USD pair works, bank spread vs interbank rate, hidden fees, when to exchange and alternatives (Revolut, Wise, no-fee cards).
3 min readHEX, RGB, HSL and CMYK: Complete Conversion for Design and Print
Convert between HEX, RGB, HSL and CMYK. Understand gamut, color profiles, why CMYK doesn't cover all RGB and how to prepare files for print.
4 min readQR Code Generator: Create Free QR, Customize and Download
Generate free QR codes for URL, text, WiFi, vCard, email, SMS. Customize colors, logo, size and margin. Download PNG, SVG. No registration, no limits.
3 min readHash & Checksum Generator: MD5, SHA-1, SHA-256, SHA-512, CRC32
Calculate cryptographic hashes (MD5, SHA-1, SHA-256, SHA-384, SHA-512, RIPEMD-160, BLAKE2b) and checksums (CRC32, CRC32C, Adler-32) from text or files. Compare integrity, verify downloads, sign data. 100 % client-side (Web Crypto API / WASM), no file uploads.
3 min readSecure Password Generator: Create Strong Passphrases and Passwords
Generate cryptographically secure random passwords (real entropy) and memorable passphrases (Diceware/EFF). Customize length, charset, exclude ambiguous chars. All client-side, zero logs.
3 min readHEX, RGB and HSL Color Codes: How They Work
Understand the HEX, RGB and HSL color codes used by designers and programmers, learn to read them and convert between them.
3 min readHow to Convert Units of Measurement Correctly
Learn to convert between metres, kilometres, grams, litres and temperatures, with tricks, conversion factors and an online calculator.
3 min readHow to Create Strong Passwords and Remember Them
Learn to create strong passwords, use password managers, enable 2FA and avoid the most common security mistakes.
2 min readWhat Is a QR Code and How It Works
Learn what a QR code is, its versions, error correction, use cases, and generate your own for free online.
2 min readWhat Is BMI and How to Interpret It
Learn what Body Mass Index is, how it is calculated, what each WHO category means and its limitations.
3 min read