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
Tea steeping temperature lookup
ideal water temp by tea type
POST /cook/tea-steep-temp$0.002Developer Utilities
Egg weight by size lookup
USDA shelled grams for S/M/L/XL/Jumbo
POST /cook/egg-weight$0.002Developer Utilities
Count leading zeros calculator
CLZ / LZCNT at 8–64 bits
POST /dev/count-leading-zeros$0.002Developer Utilities
Byte-order swap calculator
reverse bytes, hex before and after
POST /dev/byte-order-swap$0.002Developer Utilities
Decimal to fixed-point converter
Q-format integer, error and resolution
POST /dev/decimal-to-fixed-point$0.002Developer Utilities
Big integer addition calculator
exact unlimited-precision sum
POST /dev/bignum-add$0.002Developer Utilities
CIDR first and last usable host calculator
exclude network and broadcast
POST /dev/cidr-first-last-host$0.002Developer Utilities
Subnet prefix cheatsheet
mask, wildcard and host counts
POST /dev/subnet-hosts-table$0.002Developer Utilities
TCP flags decoder
SYN ACK FIN RST PSH URG from a byte
POST /dev/tcp-flags-decode$0.002Developer Utilities
Expected hash collisions calculator
n keys into m buckets
POST /dev/hash-expected-collisions$0.002Developer Utilities
Binary heap parent index calculator
0-based and 1-based arrays
POST /dev/heap-parent-index$0.002Developer Utilities
Quadtree capacity calculator
max nodes and leaves by depth
POST /dev/quadtree-capacity$0.002Developer Utilities
English word singularizer
plural noun to singular form
POST /dev/singularize-word$0.002Developer Utilities
Identifier naming case detector
camel, Pascal, snake, kebab
POST /dev/identifier-case-detect$0.002Developer Utilities
SemVer version parser
parse major, minor, patch, build
POST /dev/semver-parse$0.002Developer Utilities
Data URI size calculator
Base64 overhead from byte size
POST /dev/data-uri-size$0.002Developer Utilities
UUID to integer converter
128-bit decimal and hex
POST /dev/uuid-to-integer$0.002Developer Utilities
Hash table bucket count calculator
size m from n and load factor
POST /dev/hash-table-capacity$0.002Developer Utilities
Future value annuity due calculator
beginning-of-period FV
POST /finance/future-value-annuity-due$0.002Developer Utilities
Loan monthly payment calculator
fixed PMT from principal and rate
POST /finance/loan-monthly-payment$0.002Developer Utilities
Two loan comparison calculator
payment and total interest
POST /finance/loan-comparison$0.002Developer Utilities
Mortgage total cost calculator
full-life principal plus interest
POST /finance/mortgage-total-cost$0.002Developer Utilities
Dividend yield calculator
annual dividend over share price
POST /finance/dividend-yield$0.002Developer Utilities
FIRE target portfolio calculator
nest egg from expenses and SWR
POST /finance/fire-target-number$0.002Developer Utilities
Bond current yield calculator
annual coupon over market price
POST /finance/bond-current-yield$0.002Developer Utilities
IRA growth calculator
project IRA balance from contributions
POST /finance/ira-growth$0.002Developer Utilities
Short vs long-term capital gains calculator
compare tax owed
POST /finance/capital-gains-short-vs-long$0.002Developer Utilities
Add sales tax calculator
tax amount and gross from pre-tax price
POST /finance/sales-tax-add$0.002Developer Utilities
Contribution margin calculator
unit CM and CM ratio from price
POST /finance/contribution-margin$0.002Developer Utilities
Net present value calculator
project NPV from outlay and cash flows
POST /finance/npv$0.002Developer Utilities
Credit utilization ratio calculator
revolving balances vs limits
POST /finance/credit-utilization$0.002Developer Utilities
Return on assets calculator
ROA from net income and total assets
POST /finance/return-on-assets$0.002Developer Utilities
Working capital calculator
net working capital and current ratio
POST /finance/working-capital$0.002Developer Utilities
Impermanent loss calculator
AMM LP IL from price ratio change
POST /finance/crypto-impermanent-loss$0.002Developer Utilities
Housing cost ratio calculator
share of income spent on housing
POST /finance/housing-cost-ratio$0.002Developer Utilities
Cheaper package unit price calculator
which pack is cheaper
POST /finance/unit-price-compare$0.002Developer Utilities
Diffraction-limited aperture calculator
DLA from pixel pitch
POST /hobby/photo-diffraction-limited-aperture$0.002Developer Utilities
Graduated ND filter transition calculator
sky vs foreground
POST /hobby/photo-graduated-nd$0.002Developer Utilities
Vertical angle of view calculator
lens FOV height
POST /hobby/photo-vertical-angle-of-view$0.002Developer Utilities
Guide number from aperture and distance
GN = N × d at ISO
POST /hobby/photo-flash-guide-from-distance$0.002Developer Utilities
ISO after stops change calculator
new ISO from ±stops
POST /hobby/photo-iso-after-stops$0.002Developer Utilities
Number of bars in a song calculator
complete measures, free
POST /hobby/music-bar-count$0.002Developer Utilities
Dotted note delay time calculator
ms for rhythmic echoes
POST /hobby/music-dotted-delay$0.002Developer Utilities
Interval in cents from frequency ratio calculator
free
POST /hobby/music-ratio-to-cents$0.002Developer Utilities
Knitting rows for length calculator
rows from row gauge, free
POST /hobby/craft-knit-rows-for-length$0.002Developer Utilities
Knitting yarn yardage estimator
stitch count, gauge, consumption
POST /hobby/craft-knit-yarn-yardage$0.002Developer Utilities
D&D armor class calculator
5e AC from armor, Dex, shield
POST /hobby/dnd-armor-class$0.002Developer Utilities
D&D encounter XP budget calculator
Easy to Deadly by party
POST /hobby/dnd-encounter-xp-budget$0.002Developer Utilities
D&D passive perception calculator
5e Wisdom, proficiency, free
POST /hobby/dnd-passive-perception$0.002Developer Utilities
Catan number pip dots calculator
2d6 payout odds, free
POST /hobby/game-catan-pips$0.002Developer Utilities
Audio file size from sample rate
uncompressed WAV bytes, free
POST /hobby/music-audio-size-sample-rate$0.002Developer Utilities
Note from interval and root calculator
apply a named interval to a pitch
POST /hobby/music-note-from-interval$0.002Developer Utilities
Vibrating string fundamental frequency
f = (1/2L)√(T/μ)
POST /hobby/music-string-frequency$0.002Developer Utilities
Beads per length calculator
how many beads fit a strand
POST /hobby/craft-beads-per-length$0.002Developer Utilities
Candle Wax Amount Calculator
Weight by Jar Volume
POST /hobby/craft-candle-wax$0.002Developer Utilities
Macrame cord length calculator
cut length per working strand
POST /hobby/craft-macrame-cord$0.002Developer Utilities
Resin volume for mold calculator
volume and mixed weight
POST /hobby/craft-resin-volume-mold$0.002Developer Utilities
Darts Three-Dart Average Calculator
Points and Darts
POST /hobby/sport-darts-three-dart-average$0.002Developer Utilities
Marathon Pace from Goal Time Calculator
Per Kilometer or Mile
POST /hobby/sport-run-marathon-pace$0.002Developer Utilities
Tennis tiebreak score calculator
next serve and winner
POST /hobby/sport-tennis-tiebreak$0.002