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 — 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.
Age Calculator — Enter a birth date to get your exact age, plus your zodiac sign and the days until your next birthday. Free, in your browser.
Pyeong Calculator (Pyeong ↔ m²) — Convert between pyeong (the Korean area unit) and square meters both ways, or get pyeong from width × height. 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.

Finance · Tax

Korean Salary Take-Home Calculator (2026) — Calculate Korean take-home pay from gross annual or monthly salary with 2026 social insurance and income tax. Includes the national pension rate rise, dependents, and non-taxable pay.
Korean Severance Pay Calculator (2026) — Estimate statutory severance from join/leave dates and recent 3-month pay, including bonus and annual-leave allowance.
Korean 4 Social Insurances Calculator (2026) — Split Korea's national pension, health, long-term care, and employment insurance between employee and employer at 2026 rates. Enter a monthly salary for an instant breakdown.
Korean Hourly Wage & Holiday Pay Calculator (2026) — Turn an hourly wage and weekly hours into weekly and monthly pay including Korea's weekly holiday allowance. Compares with the 2026 minimum wage.
Korean Unemployment Benefit Calculator (2026) — Estimate daily jobseeker benefit, benefit days, and total from your average pay, age, and insured period, with 2026 upper and lower limits.
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.
Korean Income Tax Calculator (2026 rates) — Enter a tax base to get 2026 progressive income tax (6–45%), local tax, and the effective rate.
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.
Korean DSR & Loan Limit Calculator (2026) — Estimate your loan limit at the 40% DSR from income, rate, and term, and compare it with the LTV cap. Includes a stress-DSR note.
Korea Real-Estate Brokerage Fee Calculator (2026) — Enter a sale or lease amount to get the brokerage fee (bokbi) by price-band upper-limit rate. Supports monthly-rent conversion.
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.
Korean Annual Leave & Allowance Calculator (2026) — Get annual leave days from tenure, then the leave allowance from monthly ordinary wage and unused days.

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.

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.

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.