extrautil

A collection of free, practical tools.

Simple utilities that just work. No accounts, no upsells, no clutter — just useful tools, available instantly in your browser.

Tools

Compound interest explorer

Visualize how investments grow over time. Monthly contributions, FIRE retirement planning with the 4% rule, multi-currency, inflation and tax adjustments, scenario comparison, and year-by-year breakdown.

compound.extrautil.com →

Mortgage calculator

Monthly P&I, full PITI + HOA, total interest, and a year-by-year amortization schedule. Optional property tax, insurance, and HOA inputs.

mortgage.extrautil.com →

Loan & debt payoff calculator

Solve either way: payoff time given monthly payment, or required payment given target months. Extra-payment input shows months and interest saved.

loan.extrautil.com →

Currency converter

Live mid-market exchange rates between 37 currencies. Updated daily, cached locally, with offline snapshot fallback. URL-shareable conversions.

fx.extrautil.com →

Inflation calculator

What was $X worth in year Y? US CPI-based equivalence from 1913 to today, with total inflation %, average annual rate, and a year-by-year breakdown.

inflation.extrautil.com →

Cost of living & quality of life

Compare 40 major US cities and top-20 global countries on living wage, comfortable salary, median income, life expectancy, and Numbeo quality-of-life sub-indices. Sourced from BEA, BLS, HUD, Census, CDC, and Numbeo.

cost.extrautil.com →

Grocery price index

Compare the cost of a weekly grocery basket across all 50 US states + DC. State-level pricing from BEA RPPs over BLS APU national prices, with historical chart, store-tier multipliers, household scaling, and CSV export.

groceries.extrautil.com →

dev — developer & text utilities

11 fast, in-browser tools: Base64, URL encoder, JSON formatter, Unix timestamp, MD5/SHA hash, JWT decoder, color converter, regex tester, case converter, diff viewer, QR generator.

dev.extrautil.com →

ThingHaus 3D parts generator

Design practical, printable parts right in the browser. Pick a template, tune dimensions, preview the model in 3D, then download a ready-to-print STL for hooks, Gridfinity bins, stands, organizers, clips, and more.

thinghaus.com/makers →

More tools on the way

extrautil is a growing collection. The roadmap leans toward more calculators, converters, and other lightweight utilities.

Why extrautil