Return on investment and compound annual growth rate (CAGR) from a start value, end value and years held.

Future value of savings with compounding and monthly contributions: balance, contributions, interest earned, by year.

Parse a ZIP's first entry header: name, method, sizes, CRC, encryption, and zip-slip path or executable-name risks.

Read a WebP's width, height, lossy/lossless/extended format, alpha and animation flags from its first 30 bytes.

Cost per million BTU of delivered heat for resistance, heat pump, gas, propane and heating oil furnaces, from your prices.

Electric vehicle charging time, cost and range added from battery size, charge levels, charger power or circuit, and price.

Break-even units and revenue from fixed costs, unit price and unit variable cost, plus profit at a target volume.

Convert pay between hourly, weekly, biweekly, monthly and annual for a given hours per week and weeks worked.

Net present value and internal rate of return (IRR) for a list of cash flows, with a clear accept/reject-at-rate verdict.

Loan payment, total interest and amortization preview from principal, annual rate and term, monthly or other frequency.

Home price you can afford under the 28/36 rule from income, monthly debts, down payment, rate and term.

MD5, SHA-1, SHA-256 and SHA-512 digests of UTF-8 text, in hex and base64, for checksums and integrity checks.

Encode or decode text as base64, base64url, hex, URL percent-encoding or HTML entities; invalid input is reported, not guessed.

Validate an ORCID iD (researcher identifier) with its ISO 7064 check character and give the canonical form.

Parse a MAC address in any common notation: canonical forms, OUI, unicast or multicast, universal or local.

Total a list of appliances (watts, hours a day, quantity) into kWh and cost per day, month and year, with each one's share.

Size a rooftop solar system from annual kWh and peak sun hours: kW, panel count, yearly output, savings and simple payback.

Validate a 20-character Legal Entity Identifier with the ISO 7064 mod 97-10 check and split its parts.

Validate an ISSN (journal or serial number) check digit and format it with the hyphen.

Water heater recovery rate (gallons an hour), tank heat-up time and energy cost from input power, efficiency and rise.