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268+ free online tools for PDF, images, SEO, developers, color, and productivity. Fast, browser-based, and private — no signup, no installs, no limits. Search above or browse by category below.
Total tools26810.8K total uses
Categories13Active categories
Most usedJSON Formatter4.1K uses
Recently addedExperiment RandomizerNewest tool
LCM Calculator
Find the least common multiple (LCM) and GCD of two or more positive integers with prime-factor and step-by-step GCD methods.
Used 1 times•Updated 13 minutes ago
GCD Calculator
Find the greatest common divisor (GCD) and LCM of two or more positive integers with Euclidean algorithm steps and prime-factor method.
Used 1 times•Updated 28 minutes ago
Probability Calculator
Calculate basic, complement, union, intersection, conditional, and binomial probabilities with formulas and step-by-step work.
Used 1 times•Updated 24 minutes ago
Combinations Calculator
Calculate combinations nCr and permutations nPr with factorial formulas, step-by-step work, and support for large results.
Used 1 times•Updated 32 minutes ago
Standard Deviation Calculator
Calculate sample and population standard deviation and variance from any data set with squared-deviation steps.
Used 1 times•Updated 36 minutes ago
Orbital Period Calculator
Calculate orbital period from altitude or radius using Kepler's third law. Presets for ISS, geostationary orbit, Moon, and Earth around the Sun. Free, browser-based.
Used 1 times•Updated 4 minutes ago
Blackbody Radiation Calculator
Calculate blackbody peak wavelength, Stefan–Boltzmann flux, and Planck spectral radiance from temperature. Wien's law and σT⁴. Free, browser-based physics tool.
Used 1 times•Updated 30 minutes ago
Earthquake Magnitude Converter
Convert between earthquake magnitude scales — Mw, Ms, ML (Richter), mb, and Md. Estimates seismic moment, energy in joules, and TNT equivalent. Free, browser-based.
Used 1 times•Updated 29 minutes ago
Heat Index Calculator
Calculate heat index (feels-like temperature) from air temperature and relative humidity. Uses the official NWS Rothfusz formula with heat risk guidance. Free, browser-based.
Used 1 times•Updated 20 minutes ago
Dew Point Calculator
Calculate dew point from temperature and relative humidity, or find RH from temperature and dew point. Shows vapor pressure, absolute humidity, and comfort level. Free, browser-based.
Used 1 times•Updated 24 minutes ago
Humidity Calculator
Calculate relative humidity, dew point, wet-bulb temperature, vapor pressure, absolute humidity, and mixing ratio from dry-bulb readings. Free, browser-based.
Used 1 times•Updated 5 minutes ago