All tooljo tools

Generate and decode UUIDs (v1, v3, v4, v5, v7, nil) — bulk, validate, language guides.

Format, minify, validate JSON; convert to YAML — instant, browser-only.

Live markdown viewer with URL-hash sharing, MD↔HTML round-trip, and a complete cheat sheet.

Encode/decode UTF-8 text, URL-safe variant, file → data URI.

Live regex tester with capture groups, find-and-replace, and a complete syntax cheat sheet.

Decode, verify HMAC, and sign JWTs (HS256/384/512) — entirely in your browser.

MD5, SHA-1, SHA-256, SHA-384, SHA-512 — text or file. Compare two hashes to verify downloads.

Crypto-secure password / passphrase generator with real entropy meter and strength checker.

QR code generator — text, URLs, Wi-Fi, vCard. SVG + PNG download. Self-contained encoder, no upload.

Cron expression parser — explain crontab in plain English, validate, and see the next 5 fire times in your local timezone.

Text diff viewer — side-by-side + unified, line + word highlighting, ignore-whitespace + ignore-case.

Fast, free, browser-only developer tools — hub linking UUID, JSON, base64, regex, JWT, hash, password, QR, cron, diff.

Unix timestamp converter — auto-detects sec/ms/µs/ns/ISO/RFC. Live now-clock.

Hex / RGB / HSL / OKLCH converter, eyedropper, presets, recents, WCAG contrast checker.

Days between two dates, add/subtract days, live countdown to any future date.

Conversion tools hub — units, timezones, currency, color, dates, encodings.

Universal unit converter — length, weight, temperature, volume, area, speed. All conversions in your browser, no upload, instant.

Convert between timezones with DST awareness. Visual day-night strip. All major IANA timezones supported.

Currency converter with daily-updated rates. 30+ currencies. Static rate file means privacy is preserved — no external API at runtime.

Percentage calculator — what is X% of Y, X is what percent of Y, and percent increase or decrease between two numbers. Browser-only, no signup.

Mortgage payment calculator with PITI + extra-principal payoff. Shareable scenario URLs.

Personal finance hub — mortgage, debt, loan, compound interest, FIRE, retirement, savings, refinance, ROI, and more. Plain-English math, browser-only.

Free debt payoff calculator — snowball + avalanche methods. See your debt-free date, total interest, and the optimal order to pay debts off.

Compound interest calculator — see how monthly contributions plus time grow your money. Daily/monthly/annual compounding, year-by-year table, shareable URLs. Browser-only, no signup.

FIRE calculator — financial independence / retire early. Your FIRE number from the 4% rule, years to FI, progress, and a real-return projection. Browser-only, no signup.

Savings goal calculator — set a target and date to get the monthly amount you need, or set a monthly amount to see when you'll hit the goal. Browser-only, no signup.

Loan calculator — monthly payment, total interest, and full amortization schedule for car, personal, and student loans. Shareable URLs, browser-only.

Salary to hourly calculator — convert an annual salary to hourly, daily, weekly, biweekly, and monthly pay, and back again. Adjust hours per week and weeks per year. Browser-only, no signup.

ROI calculator — return on investment percentage, total gain or loss, and annualized return (CAGR) from a starting value, ending value, and holding period. Browser-only, no signup.

Mortgage refinance calculator — compare your current loan to a new rate and term. Monthly savings, break-even month on closing costs, and lifetime interest difference. Browser-only, no signup.

Inflation calculator — see how inflation erodes buying power over time. What a sum will cost in the future and what it will be worth in today's dollars, at any assumed rate. Browser-only, no signup.

APY calculator — convert APR to APY (effective annual yield) and see how compounding frequency changes your real return. Compare annual, monthly, daily, and continuous. Browser-only, no signup.

Sales tax calculator — add sales tax to a price or pull it out of a tax-inclusive total. Any rate, instant, browser-only, no signup.

Tip calculator — tip amount, total, and per-person split for any bill. Quick 15/18/20/25% presets, custom rate. Browser-only, no signup.

Discount calculator — final price after a percent-off, the amount you save, and stacked discounts. Browser-only, no signup.

Home affordability calculator — how much house you can afford from income, debts, down payment, and rate, using the 28/36 DTI rule. Browser-only, no signup.

Retirement calculator — project your 401(k) balance with employer match, contribution rate, and expected return. See how much the match adds. Browser-only, no signup.

Credit card payoff calculator — months to clear a balance, total interest, and the minimum-payment trap. Browser-only, no signup.

CD calculator — maturity value and interest earned on a certificate of deposit from your deposit, APY, and term. Browser-only, no signup.

Emergency fund calculator — how big your safety net should be (3–12 months of expenses), the gap to your target, and how long to get there. Browser-only, no signup.

Retirement drawdown calculator — how long your savings last at a given withdrawal and return, or whether withdrawals are sustainable. Browser-only, no signup.

Annuity calculator — the monthly income a lump sum provides over a set term at a given return, plus total payout and interest earned. Browser-only, no signup.

Dividend calculator — annual, quarterly, and monthly income from a dividend yield, plus a reinvestment (DRIP) growth projection. Browser-only, no signup.

Simple interest calculator — interest and total from principal, rate, and time using I = P x r x t, with a side-by-side compound comparison. Browser-only, no signup.

Budget calculator — split your monthly take-home pay with the 50/30/20 rule (needs, wants, savings), or your own percentages. Browser-only, no signup.

Cap rate calculator — capitalization rate, NOI, monthly cash flow, and cash-on-cash return for a rental property. Browser-only, no signup.

Startup runway calculator — how many months of cash you have left from your burn rate, and your zero-cash date. Browser-only, no signup.

Running pace + splits + Riegel race-time predictor. Marathon, half, 10K, 5K presets.

Concept2 RowErg / SkiErg / BikeErg watts ↔ split ↔ time ↔ distance.

Health hub — BMI, BMR, TDEE, and macro calculators. Plain-English math, browser-only.

Free BMI calculator — metric and imperial inputs, WHO + Asian-population thresholds. Browser-only, no signup, no health data uploaded.

Free BMR calculator — basal metabolic rate via Mifflin-St Jeor (modern) and Harris-Benedict. Browser-only.

Free TDEE calculator — total daily energy expenditure with sensitivity ranges. Browser-only.

Free macro calculator — TDEE → calorie target → protein/carb/fat split. Cut/maintain/bulk modes.

Marketing hub — UTM builder, ROAS, CPC/CPM, profit margin, payment fees, conversion rate, and break-even. Browser-only, no signup.

Free UTM-parameter builder for Google Analytics, Mixpanel, Amplitude. Validates the standard 5 fields, shareable scenario URLs, no signup.

Free ROAS calculator — return on ad spend, break-even ROAS for a target margin, inverse mode. Browser-only, no signup.

Free profit margin calculator — cost and price → margin %, plus markup conversion. Browser-only, no signup.

Free payment-fee calculator for Stripe, PayPal, Square. Net after fees + inverse (what to charge to net $X). No signup.

Free CPC and CPM calculator — cost per click, cost per thousand, cross-conversion via CTR. No signup.

Free conversion rate calculator with Wilson score 95% confidence intervals — honest math for small samples.

Break-even calculator — the units and revenue you need to cover fixed costs given your price and variable cost per unit. Browser-only, no signup.