免費線上工具
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
Trigonometry Calculator
Compute sin, cos, tan, csc, sec, cot, and inverse trig functions in degrees or radians with exact values and step-by-step work.
Used 0 times•Updated never
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
Star Distance Calculator
Calculate star distance from parallax or magnitude. Convert between parsecs, light-years, AU, and km. Free, instant, browser-based astronomy tool.
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
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