Free Online Tools
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
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
Solar Angle Calculator
Calculate solar elevation, azimuth, and noon altitude from latitude, date, and time. Find shadow length from sun angle and object height. Free, browser-based.
Used 0 times•Updated never
Moon Phase Calculator
Find the moon phase for any date — new moon, full moon, quarters, and crescents. Shows illumination %, moon age, and days to next new or full moon. 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
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
Astronomical Unit Converter
Convert astronomical units (AU) to light-years, parsecs, kilometers, meters, and miles. Enter any distance and get instant conversions with formulas. 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
Exoplanet Habitability Calculator
Assess exoplanet habitability with habitable zone, equilibrium temperature, and Earth Similarity Index (ESI). Presets for Earth, Proxima b, and Kepler-186f. Free, browser-based.
Used 0 times•Updated never
Constellation Finder
Find constellations by RA/Dec coordinates, search all 88 IAU constellations by name, or list what's visible tonight from your location. Free, browser-based.
Used 0 times•Updated never
Richter Scale Calculator
Calculate Richter magnitude from seismograph amplitude and distance, explore effects and energy for any ML value, or compare two magnitudes. Free, browser-based.
Used 0 times•Updated never