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
Buy one get one discount calculator
BOGO effective % free
POST /life/bogo-discount$0.002Developer Utilities
Recipe cost per serving calculator
ingredient costs ÷ servings, free
POST /life/cost-per-serving$0.002Developer Utilities
Shared expense splitter
itemized costs by weight free
POST /life/expense-split$0.002Developer Utilities
Quit a habit savings calculator
money saved by quitting free
POST /life/habit-savings$0.002Developer Utilities
Markup to margin converter
selling price, free
POST /life/markup-margin$0.002Developer Utilities
Overtime pay calculator
hourly rate, OT hours, gross pay, free
POST /life/overtime-pay$0.002Developer Utilities
Price per 100g calculator
compare products, find cheapest, free
POST /life/price-per-100g$0.002Developer Utilities
Rule of 114 and 144 calculator
years to triple or quadruple free
POST /life/rule-of-114$0.002Developer Utilities
Salary to hourly converter
annual pay to hourly wage free
POST /life/salary-to-hourly$0.002Developer Utilities
Sales tax calculator
tax amount and total from rate, free
POST /life/sales-tax$0.002Developer Utilities
Savings goal time calculator
months to target with fixed deposits
POST /life/savings-goal-time$0.002Developer Utilities
Subscription annual cost calculator
monthly & yearly totals, free
POST /life/subscription-annual$0.002Developer Utilities
Tip and split calculator
bill, tip %, per person, free
POST /life/tip-split$0.002Developer Utilities
Unit price comparison calculator
price per unit and best value, free
POST /life/unit-price$0.002Developer Utilities
Arithmetic sequence calculator
nth term and partial sum, free
POST /math/arithmetic-sequence$0.002Developer Utilities
Arithmetic series sum calculator
S = n(a1+an)/2, free
POST /math/arithmetic-series-sum$0.002Developer Utilities
Catalan number calculator
nth Catalan C(n), free
POST /math/catalan-number$0.002Developer Utilities
Double factorial calculator
compute n!! with BigInt precision
POST /math/double-factorial$0.002Developer Utilities
Factorial calculator
n! exact BigInt product, free
POST /math/factorial-calculator$0.002Developer Utilities
Fibonacci number calculator
nth term and sequence, free
POST /math/fibonacci$0.002Developer Utilities
Sum of Fibonacci series
first n terms equal F(n+2)−1
POST /math/fibonacci-sum$0.002Developer Utilities
Infinite geometric series sum
S = a/(1−r), free calculator
POST /math/geometric-series-sum$0.002Developer Utilities
Hexagonal number calculator
H(n)=n(2n−1) and membership test, free
POST /math/hexagonal-number$0.002Developer Utilities
Look-and-say sequence
n-th term from a seed by run-length
POST /math/look-and-say$0.002Developer Utilities
Padovan sequence calculator
n-th Padovan number P(n)
POST /math/padovan-number$0.002Developer Utilities
Pentagonal number calculator
P(n)=n(3n−1)/2 and membership test
POST /math/pentagonal-number$0.002Developer Utilities
Polygonal number calculator
n-th s-gonal figurate number
POST /math/polygonal-number$0.002Developer Utilities
Primorial calculator
n# product of primes ≤ n, free
POST /math/primorial$0.002Developer Utilities
Square pyramidal number
sum of first n squares n(n+1)(2n+1)/6
POST /math/pyramidal-number$0.002Developer Utilities
Stern diatomic / Stern-Brocot sequence
n-th term s(n)
POST /math/stern-brocot$0.002Developer Utilities
Sum of first n even numbers
2+4+…+2n = n(n+1)
POST /math/sum-of-even$0.002Developer Utilities
Sum of first n odd numbers
equals n squared, free calculator
POST /math/sum-of-odd$0.002Developer Utilities
Sum of first n squares
1²+2²+…+n² = n(n+1)(2n+1)/6
POST /math/sum-of-squares$0.002Developer Utilities
Sylvester sequence calculator
nth term with BigInt, free
POST /math/sylvester-sequence$0.002Developer Utilities
Angular velocity calculator
ω from angle & time or RPM, free
POST /mech/angular-velocity$0.002Developer Utilities
Atwood machine calculator
acceleration & tension, free in browser
POST /mech/atwood-machine$0.002Developer Utilities
Average velocity calculator
displacement over time in m/s and km/h free
POST /mech/average-velocity$0.002Developer Utilities
Banked curve calculator
ideal banking angle from radius and speed
POST /mech/banked-curve$0.002Developer Utilities
Centripetal acceleration calculator
a = v²/r from speed and radius free
POST /mech/centripetal-acceleration$0.002Developer Utilities
Centripetal force calculator
F=mv²/r from mass, speed, and radius
POST /mech/centripetal-force$0.002Developer Utilities
Coefficient of friction calculator
μ = Ff / N, free in browser
POST /mech/coefficient-of-friction$0.002Developer Utilities
Elastic collision calculator
final velocities of two masses in 1D free
POST /mech/elastic-collision$0.002Developer Utilities
Force calculator
F=ma from mass and acceleration (or solve mass/accel)
POST /mech/force-mass-accel$0.002Developer Utilities
Free fall calculator
fall time and impact velocity from rest
POST /mech/free-fall$0.002Developer Utilities
Hooke's law calculator
spring force F=kx (or solve k or x)
POST /mech/hookes-law$0.002Developer Utilities
Horizontal projectile motion calculator
fall time, range and impact velocity free
POST /mech/horizontal-projectile$0.002Developer Utilities
Impulse calculator
impulse and Δp from force and contact time
POST /mech/impulse$0.002Developer Utilities
Inclined plane calculator
acceleration and normal force free
POST /mech/inclined-plane$0.002Developer Utilities
Kinematics distance calculator
displacement from velocity, acceleration, time
POST /mech/kinematics-distance$0.002Developer Utilities
Final velocity calculator
v = u + at, free in browser
POST /mech/kinematics-velocity$0.002Developer Utilities
Kinetic energy calculator
KE = ½mv², free in browser
POST /mech/kinetic-energy$0.002Developer Utilities
Moment of inertia calculator
ring, disc, sphere, rod, free
POST /mech/moment-of-inertia$0.002Developer Utilities
Momentum calculator
linear momentum p=mv in kg·m/s free
POST /mech/momentum$0.002Developer Utilities
Newton's second law calculator
F = ma, free in browser
POST /mech/newton-second-law$0.002Developer Utilities
Pendulum length calculator
required length from period and g free
POST /mech/pendulum-length$0.002Developer Utilities
Power calculator
mechanical power in watts and horsepower from work and time
POST /mech/power$0.002Developer Utilities
Power from force and velocity
P=Fv in watts free
POST /mech/power-force-velocity$0.002Developer Utilities
Projectile from height calculator
range and flight time above ground
POST /mech/projectile-launch-from-height$0.002Developer Utilities
Pulley mechanical advantage calculator
ideal IMA and effort force free
POST /mech/pulley-mechanical-advantage$0.002Developer Utilities
Rotational kinetic energy calculator
KE=½Iω² in joules free
POST /mech/rotational-kinetic-energy$0.002