All tooljo tools

36 tools live across the network, each on its own subdomain, each 100% in your browser. Pick one — bookmark it — never see this page again.

Developer tools

Encode, decode, validate, generate. Built for the address bar.

GUID / UUID

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

JSON

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

Markdown

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

Base64

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

Regex

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

JWT

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

Hash

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

Password

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

QR

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

Cron

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

Diff

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

Dev tools

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

Utilities

Date, time, color, conversions — the things you Google five times a week.

Epoch

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

Color

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

Date

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

Converters

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

Unit converter

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

Timezone converter

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

Currency converter

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

Finance

Plain-English calculators with shareable scenarios. No email gate.

Mortgage

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

Personal finance

Personal finance hub — mortgage, debt payoff, plus FIRE / compound interest / savings goal coming soon.

Debt payoff

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

Fitness + cardio

Pace, splits, race prediction, erg watts. Honest math.

Running pace

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

Erg calculator

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

Health

Health hub — BMI live, plus BMR / TDEE / calorie / macro tools coming soon. Plain-English math, browser-only.

BMI calculator

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

BMR calculator

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

TDEE calculator

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

Macro calculator

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