Developer Utilities

Small developer utilities that save a trip to a random website. Encode and decode Base64, explain a regex, build UTM links, generate QR codes and vCards, and more — the everyday helpers. Free in your browser, and available by API when you need them in a script.

Developer Utilities
Arccos calculator
inverse cosine in radians and degrees
POST /math/arccos$0.002
Developer Utilities
Arcsin calculator
inverse sine in radians and degrees
POST /math/arcsin$0.002
Developer Utilities
Arctangent calculator
atan(x) in radians
POST /math/arctan$0.002
Developer Utilities
Arcus tangent calculator
inverse tangent in radians and degrees
POST /math/arcus-tangent$0.002
Developer Utilities
Area calculator
square, rectangle, triangle and circle
POST /math/area$0.002
Developer Utilities
Oblique triangle area calculator
area from two sides and included angle
POST /math/area-oblique-triangle$0.002
Developer Utilities
Obtuse triangle area calculator
from base and height or three sides
POST /math/area-obtuse-triangle$0.002
Developer Utilities
Area of a circle calculator
π·r² from the radius, free online
POST /math/area-of-a-circle$0.002
Developer Utilities
Area of a trapezoid calculator
(a+b)/2·h from bases and height, free
POST /math/area-of-a-trapezoid$0.002
Developer Utilities
Look up paper size dimensions in mm and inches
POST /misc2/paper-size-lookup$0.002
Developer Utilities
Convert shoe size between US, UK, and EU regions
POST /misc2/shoe-size-convert$0.002
Developer Utilities
Child allowance calculator by age
suggested weekly amount
POST /parent/allowance-calculate-by-age$0.002
Developer Utilities
Pet life stage calculator
classify dogs and cats by age and size
POST /pet/age-life-stage-classify$0.002
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Calculate next pet vaccination due date
POST /pet/vaccination-schedule-due$0.002
Developer Utilities
Acceleration due to gravity calculator
g at altitude in m/s², free
POST /phys/acceleration-due-to-gravity$0.002
Developer Utilities
Acceleration of a charged particle in an electric field
a = qE/m
POST /phys/acceleration-of-particle-in-electric-field$0.002
Developer Utilities
Acceleration calculator
a = F/m from force in N and mass in kg
POST /phys/acceleration-using-force-and-mass$0.002
Developer Utilities
Acoustic impedance calculator
Z = ρ·c in Rayls, free
POST /phys/acoustic-impedance$0.002
Developer Utilities
Air density calculator
kg/m³ from pressure, temperature and humidity
POST /phys/air-density$0.002
Developer Utilities
Air pressure at altitude calculator
barometric formula, hPa or inHg
POST /phys/air-pressure-at-altitude$0.002
Developer Utilities
Alfvén velocity calculator
v = B/√(μρ) in m/s, free
POST /phys/alfven-velocity$0.002
Developer Utilities
Alien civilizations calculator
Drake equation estimate
POST /phys/alien-civilization$0.002
Developer Utilities
Temperature at altitude calculator
standard lapse rate, °C or °F
POST /phys/altitude-temperature$0.002
Developer Utilities
Amp to wire size calculator
minimum copper AWG for current and length
POST /phys/amp-to-wire-size$0.002
Developer Utilities
Angle of incidence calculator
refraction angle from n1, n2, free
POST /phys/angle-of-incidence$0.002
Developer Utilities
Angle of refraction calculator
Snell's law with critical angle, free
POST /phys/angle-of-refraction$0.002
Developer Utilities
Angle of twist calculator
solid circular shaft torsion in radians, free
POST /phys/angle-of-twist$0.002
Developer Utilities
Angular frequency calculator
ω = 2πf from hertz to rad/s, free
POST /phys/angular-frequency$0.002
Developer Utilities
Angular resolution calculator
Rayleigh criterion in arcseconds, free
POST /phys/angular-resolution$0.002
Developer Utilities
Aperture area calculator
light-collecting area from diameter
POST /phys/aperture-area$0.002
Developer Utilities
API gravity calculator
degrees API from specific gravity, free
POST /phys/api-gravity$0.002
Developer Utilities
Arrow speed calculator
fps from draw weight, draw length and arrow mass
POST /phys/arrow-speed$0.002
Developer Utilities
Attenuation in dB
loss between input and output power levels
POST /phys/attenuation$0.002
Developer Utilities
Ballistic coefficient calculator
mass, drag coefficient and area
POST /phys/ballistic-coefficient$0.002
Developer Utilities
Bank angle calculator
level-turn bank from speed and radius
POST /phys/bank-angle$0.002
Developer Utilities
Barn-pole paradox calculator
Lorentz contraction and fit verdict
POST /phys/barn-pole-paradox$0.002
Developer Utilities
Belt length calculator
two pulleys and center distance, free
POST /phys/belt-length$0.002
Developer Utilities
Bend allowance calculator
arc length from angle, radius and K-factor
POST /phys/bend-allowance$0.002
Developer Utilities
Binoculars range calculator
maximum resolving distance
POST /phys/binoculars-range$0.002
Developer Utilities
Biot number calculator
Bi = h·L/k, lumped-capacitance, free
POST /phys/biot-numer$0.002
Developer Utilities
Rent vs buy cost calculator
compare total housing costs
POST /realestate/rent-vs-buy-compare$0.002
Developer Utilities
Build a Content-Security-Policy header from allowed sources
POST /security/csp-header-build$0.002
Developer Utilities
Convert Unix permissions between symbolic and octal
POST /security/file-permission-symbolic-convert$0.002
Developer Utilities
Seeded memorable passphrase generator
deterministic Diceware-style words
POST /security/passphrase-generate-seeded$0.002
Developer Utilities
Daily trip budget calculator
allocate lodging, food and activities
POST /travel2/trip-budget-per-day$0.002
Developer Utilities
Calculate exact age
years, months and days
POST /calc2/age-calculate$0.002
Developer Utilities
Calculate body mass index
metric or imperial BMI
POST /calc2/bmi-calculate$0.002
Developer Utilities
Count business days between dates
weekdays and holidays
POST /calc2/business-days-count$0.002
Developer Utilities
Compound interest calculator
final amount and interest earned
POST /calc2/compound-interest$0.002
Developer Utilities
Convert currency with a given exchange rate
POST /calc2/currency-convert-static$0.002
Developer Utilities
Calculate days between dates
days, weeks and months
POST /calc2/date-difference$0.002
Developer Utilities
Get the day of the week from a date
weekday calculator
POST /calc2/day-of-week-from-date$0.002
Developer Utilities
Calculate discounted price, final cost, and total savings
POST /calc2/discount-price$0.002
Developer Utilities
Calculate trip fuel cost from distance, efficiency and fuel price
POST /calc2/fuel-cost-trip$0.002
Developer Utilities
Calculate GPA from grades and credit hours
POST /calc2/gpa-calculate$0.002
Developer Utilities
Calculate target heart rate zones with the Karvonen method
POST /calc2/heart-rate-zones$0.002
Developer Utilities
Ideal weight range calculator
Devine and Robinson estimates
POST /calc2/ideal-weight-range$0.002
Developer Utilities
Check if a year is a leap year
Gregorian leap year calculator
POST /calc2/leap-year-check$0.002
Developer Utilities
Convert percentage to letter grade
standard or custom scale
POST /calc2/letter-grade-from-percent$0.002
Developer Utilities
Calculate a loan amortization schedule row
POST /calc2/loan-amortization-row$0.002