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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
Permutations Calculator
Calculate permutations nPr and factorials n! for ordered arrangements with formulas and step-by-step work.
Used 0 times•Updated never
Regression Calculator
Fit a linear regression line to (x, y) data — slope, intercept, equation, correlation r, R², and predictions with step-by-step work.
Used 0 times•Updated never
Z Score Calculator
Convert raw scores to z-scores and back using z = (x − μ) ÷ σ, with percentile and step-by-step work.
Used 0 times•Updated never
Planet Weight Calculator
Find your weight on Mercury, Venus, Mars, Jupiter, the Moon, and other worlds. Enter Earth weight in kg or lb and compare surface gravity instantly. Free, browser-based.
Used 0 times•Updated never
Light Year Converter
Convert light-years to parsecs, AU, kilometers, meters, and miles. Enter any astronomical distance and get instant conversions with formulas. Free, browser-based.
Used 0 times•Updated never
Escape Velocity Calculator
Calculate escape velocity from mass and radius or surface gravity. Presets for Earth, Moon, Mars, Jupiter, and more. Results in km/s and m/s. Free, browser-based.
Used 0 times•Updated never
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 0 times•Updated never
Sunrise Sunset Calculator
Calculate sunrise, sunset, solar noon, and day length for any location and date. Enter latitude, longitude, and UTC offset. Free, browser-based astronomy tool.
Used 0 times•Updated never
Redshift Calculator
Calculate cosmological redshift from wavelengths or recession velocity. Convert z to velocity, Hubble distance, and scale factor. Free, browser-based astronomy tool.
Used 0 times•Updated never
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 0 times•Updated never
Telescope Magnification Calculator
Calculate telescope magnification from focal lengths. Get exit pupil, true field of view, resolving power, and light grasp. Find eyepiece or scope FL for target magnification. Free, browser-based.
Used 0 times•Updated never
Gravity on Other Planets
Compare surface gravity on Mercury, Venus, Mars, Jupiter, the Moon, and every planet. See gravity in m/s², percent of Earth, and weight for any mass. Free, browser-based.
Used 0 times•Updated never