About ToolHub

ToolHub is a collection of free online web tools accessible to everyone without registration or payment. We offer tools spanning image processing, PDF handling, developer utilities, design, and unit conversion.

Who runs this site

ToolHub is built and run by an independent developer. The tools started as things I needed for my own work, and I published them thinking others might be looking for the same. The rates and thresholds in the calculators are taken from official government notices. If you find an error or need a tool that is missing, email usecase84@gmail.com and I will reply.

Complete Privacy

Every tool on ToolHub processes data entirely in your browser — no server involved. Files you upload (images, PDFs) and data you enter never leave your device. Nothing is stored on our servers. When you close your browser tab, all processed data is gone.

Free to Use

All features on ToolHub are completely free, with no sign-up required and no usage limits. There are no watermarks on generated output. The service is sustained by advertising revenue; we do not charge users directly.

Available Tools

Image

Image Compressor & Converter — Reduce image and photo file size in your browser, and convert between PNG, JPG, and WebP. No upload—shrink files for email and web with minimal quality loss.
Image Resizer & Cropper · Social Media — Freely crop and resize images, or fit Instagram, YouTube, and blog specs. Preset ratios avoid awkward crops—processed locally in your browser.
Image Resizer — Resize photos by exact pixels, percentage, or longest side. Keep the aspect ratio, convert between PNG, JPG and WebP, and see the output file size — all in your browser.
Passport & ID Photo Resizer — Crop and resize passport or ID photos to official specs. Presets for 35×45mm (413×531px), US visa 2×2in and more, with a head-size guide and a 500KB size check — all in your browser.

Docs · PDF

Combine & Merge PDF · Split — Merge PDFs in order or split pages locally in your browser. Files never leave your device—free, no install, for contracts and reports.
PDF to JPG Converter · Image ↔ PDF — Extract PDF pages to JPG/PNG or bundle images into a PDF. Set DPI for sharp output—files processed locally, never uploaded.
Compress PDF — Shrink PDF size in your browser. Pick a compression level to lighten scanned or image-heavy PDFs — no upload, free.

Developer

JSON Formatter & Converter — Format, validate, and convert JSON to CSV or YAML in one view. Debug APIs and config files locally—free, nothing sent to a server.
Base64 Encoder & Decoder — Encode and decode text or images to Base64 for Data URLs and API tests. RFC-style conversion in your browser—private and free.
Diff Checker / Text Compare — Compare two texts or code snippets line by line or by character. Spot contract and config changes—paste stays local, no upload.
Regex Tester & Cheat Sheet — Test regex patterns live with flags and a cheat sheet. Parse emails, URLs, and logs—pattern and sample text never leave the browser.
URL Encoder & Decoder — Encode or decode URLs with encodeURIComponent for UTF-8 and special chars. Fix broken query strings—processed locally, free.

Design

Color Palette Generator — Build harmonious palettes and copy HEX, RGB, and HSL. Check WCAG contrast and export CSS or Tailwind tokens—all in your browser.
SVG Image Converter — Export SVG vectors to PNG or JPG at any scale. Keep transparency or set a background—local conversion, no server upload.
CSS Box-Shadow Generator — Dial blur, spread, offset, and color to build box-shadow CSS with live preview. Copy inset shadows—free, no install required.
CSS Gradient Generator — Preview linear and radial gradients and copy background CSS. Set angle and color stops for cards and buttons—in your browser.
CSS clamp() Calculator — Generate responsive clamp(min, preferred, max) for font-size and spacing. Fluid sizing without extra media queries—copy one line.

Convert · Calc

Unit Converter — Convert length, weight, temperature, area, and data units instantly. Metric vs imperial for travel, cooking, and dev—free in-browser.
Pixels ↔ cm / mm Converter (DPI) — Convert pixels to centimetres, millimetres, inches and points at a chosen DPI, plus a table of common print specs such as passport photos and A4 in pixels.
Loan & Interest Calculator (Compound) — Work out a monthly loan payment and a compound-interest maturity value in one place. Quick estimates for mortgages, personal loans and savings, right in your browser.
Currency Exchange Rate Calculator — Convert dollars, won, yen, euro and more at live rates. European Central Bank reference rates, updated daily. Free, in your browser.
Percent Calculator (Discount, Ratio & Change) — Calculate discounts, ratios, and percent change instantly. Reverse sale price and savings—no spreadsheet, free in your browser.
Date & D-Day Calculator — Count days to a target date (D-day), find the difference between two dates, or add and subtract days. Free, in your browser.
Korean Age Calculator (International vs Korean Age) — Convert a birth date into international age, the old Korean counting age, and Korean "year age" side by side — plus your zodiac animal and days to your next birthday. Free, in your browser.
Pyeong Calculator: Pyeong to m², Square Feet & Acres — Convert pyeong (the Korean area unit) to square meters, square feet and acres both ways, or get pyeong from width × height in meters, centimeters or feet. Free, in your browser.
BMI Calculator — Calculate your BMI from height and weight and see whether you're underweight, normal, overweight, or obese—plus your healthy weight range. Free, in your browser.
GPA Calculator — Enter each course's credits and grade to get your weighted GPA, with 4.5 / 4.3 / 4.0 scales and a 100-point estimate. Free, in your browser.
Timer & Stopwatch — A countdown timer with a beep and a lap stopwatch, together in one screen. No install — free, in your browser.
World Clock & Time Zone Converter — See the current time in major cities at a glance and convert any time between time zones. Daylight saving handled automatically. Free, in your browser.
Ovulation & Period Calculator (Fertile Window) — Enter your last period and cycle length to see your next period, ovulation day and fertile window for the next 3 cycles, with a color-coded calendar. Free, private, in your browser.
Korean Lunar Calendar Converter (Solar ↔ Lunar) — Convert between solar and Korean lunar dates with leap months, weekday, zodiac animal and sexagenary year. Find lunar birthdays, Seollal and Chuseok dates. Free, 1900–2100.
Pregnancy Due Date Calculator (Weeks Pregnant) — Find your estimated due date from your last period or conception date (Naegele's rule), plus weeks pregnant, trimester, countdown and key milestone dates. Free in your browser.
Time Calculator (Add & Subtract Hours and Minutes) — Add and subtract hours and minutes to total your work or study time, find the duration between two times (overnight shifts included), and add hours to a clock time. Free, in your browser.
Korean Military Discharge Date Calculator — Pick an enlistment date and service branch to see the discharge date (전역일), days left, days served and a progress bar for Korean military service. Free, in your browser.

Finance · Tax

Korea Salary Calculator: Take-Home Pay for Locals & Foreigners (2026) — Work out Korean take-home pay from a gross annual or monthly salary with 2026 social insurance and income tax — with options for foreign workers: the 19% flat tax, pension exemption and no unemployment insurance.
Korea Severance Pay Calculator (2026, incl. Foreign Workers) — Estimate Korean statutory severance from your join and leave dates and recent 3-month pay, including bonus and annual-leave allowance — the same rules apply to foreign workers.
Korea 4 Major Insurances Calculator — incl. Foreign Workers (2026) — Split Korea’s national pension, health, long-term care and employment insurance between employee and employer at 2026 rates, with options for foreign workers who are exempt from the pension or unemployment insurance.
Korea Minimum Wage & Hourly Pay Calculator (2026) — Turn an hourly wage and weekly hours into weekly and monthly pay with Korea’s weekly holiday allowance, and compare it with the 2026 minimum wage of 10,320 KRW an hour.
Korea Unemployment Benefit Calculator (2026, incl. Foreign Workers) — Estimate Korea’s daily jobseeker benefit, benefit days and total from your average pay, age and insured period with 2026 limits — and check whether your visa is covered.
Korean VAT Calculator (add & extract 10%) — Add 10% VAT to a net amount, or split a gross total into net and VAT. Based on standard Korean VAT.
Korea Tax Refund Calculator for Tourists (VAT Refund) — Enter your shopping receipts to see which qualify for Korea’s tourist tax refund, where you can claim each one (instant at the store or at the airport) and roughly how much VAT you’ll get back.
Korea Income Tax Calculator — 19% Flat Tax for Foreigners (2026) — Get 2026 Korean progressive income tax (6–45%) and local tax from a tax base, or compare the 19% flat tax for foreigners with the regular rates on your salary.
Korean Gift Tax Calculator (2026) — Estimate gift tax from the gift value and relationship, applying the 10-year deduction, rates, and a 3% filing credit.
Korean Property Tax Calculator (2026 housing) — Enter the published price to estimate housing property tax and local education tax using the 2026 fair-value ratio and rates. Supports the 1-home special.
Korean Acquisition Tax Calculator (2026 housing) — Enter purchase price and area to estimate housing acquisition tax by price band, plus local education and rural special taxes.
Korean Capital Gains Tax Calculator (2026, simplified) — Estimate capital gains tax from the gain, holding period, and asset type with the basic deduction and rate. Exemptions and surcharges excluded.
Loan Repayment Calculator (Amortization) — Compare equal-payment, equal-principal and interest-only loans, build a period-by-period amortization schedule, and copy the matching Excel PMT formulas or export CSV.
Korea Mortgage Loan Limit Calculator: DSR & LTV (2026) — Estimate your Korean mortgage limit at the 40% DSR from income, rate and term, and compare it with the LTV cap — with notes for foreigners buying a home in Korea.
Korea Real Estate Agent Fee Calculator: Jeonse, Wolse & Sale (2026) — Enter a sale price, jeonse deposit or deposit plus monthly rent to get the maximum Korean real estate agent fee (bokbi) by price band, with a quick guide to jeonse vs wolse for foreigners.
Korean Loan Prepayment Fee Calculator (2026) — Enter prepaid principal, fee rate, and elapsed time to get the prepayment fee, prorated by the remaining fee period.
Korea Annual Leave Calculator: Days & Unused Leave Pay (2026) — Work out paid annual leave days under Korean labor law from your tenure, then the cash allowance for unused days from your ordinary wage — the same rules apply to foreign employees.
Savings & Deposit Interest Calculator (Korea, After Tax) — Enter a deposit or monthly savings amount, rate and term to see simple or monthly-compound interest and your payout after Korea’s 15.4% interest tax. Free, in your browser.
Korea Car Tax Calculator (Annual Vehicle Tax by cc) — Estimate Korea’s annual car tax (자동차세) for a private car from engine size and registration year, with education tax, June/December bills and the January prepayment discount.

Generate

QR Code Generator — Create QR codes for URLs, text, contacts, and Wi-Fi; download PNG or SVG. Tips for scan-friendly design—generated locally, free.
Password Generator & Strength Checker — Generate strong passwords and score strength in real time. Length and charset options—credentials created only in your browser.
Lotto Number Generator & Random Picker — Generate Korean Lotto 6/45 numbers as colored balls, and draw random winners from your own list — all in your browser, free.
Ghost Leg (Ladder Game) — Enter players and outcomes to draw a random ladder and trace each path. Fair for bets, ordering, or team picks — free, in your browser.
Spin the Wheel · Random Picker Wheel — An online spinner wheel with your own entries — no slot limit. Pick lunch, dares, or winners, and remove the winner before the next spin. Free, in your browser.
Draw Lots Online (Random Card Draw) — Draw lots online: set players and winning cards, then flip shuffled cards to reveal Winner or Try again. Use your own list too. Free, right in your browser.

Text

Character Counter — Count characters, words, lines, and UTF-8 bytes as you type. Hit SNS and SMS limits before you post—text stays in the browser.
Case Converter — Convert to UPPER, lower, Title, camelCase, snake_case, and kebab-case. Rename variables and files—processed only in your browser.
Korean Name Romanizer — Convert a Korean name into passport-style Roman letters, with common surname spellings and the official Revised Romanization. Free, in your browser.
Special Characters & Symbols (Click to Copy) — Copy and paste special characters — stars, hearts, arrows, check marks, math, units, currency, circled numbers and more. One click copies; collect several and copy them at once. Free, in your browser.

Technology

ToolHub is built with Next.js 14 App Router as a fully static site. It uses TypeScript and Vanilla CSS, deployed on Render Static Site for fast, cold-start-free delivery.

Contact

For questions or suggestions, please visit our Contact page.