About

Utilo is a free collection of online tools that work right in your browser, with no sign-up and nothing to install. The English site has 15 tools in 3 categories, from file converters to team splitters and dice. The Korean site has more, including date, money and travel calculators.

Who runs it

Utilo is made and maintained by one person who goes by Dogujangi ("tool maker"). In one line: someone who builds small everyday tools you can use right away, with no sign-up.

When you need a quick calculation or conversion and search for one, many sites ask you to sign up first, surround the page with ads, or leave it unclear where your input goes. So the aim here is to gather the tools people reach for often in one place, process what you enter inside your browser, and be open about how each calculation works and where it falls short. The site opened in October 2026, and tools and guides are still being added. Messages and bug reports are read by the operator at contact@useutilo.com.

Tool categories

The tools are grouped by what they are for. Each category page explains which tool fits which situation.

• Games & groups (6 tools)
• Image & video (4 tools)
• File conversion (5 tools)

How we build

• What you enter into a tool, and the files you choose, are not sent to the operator's server. They are processed inside your browser. Outside services that load with each page, such as ads and the font, are described in the privacy policy.
• Every tool works on a single screen. The tool comes first, and the instructions and explanation are below it.
• Each tool page states how it calculates and where its limits are, including inputs it cannot handle well.

How tools are made and checked

All of the tools run as JavaScript inside your browser. Tools with random results, such as the wheel, dice and team splitter, use the browser's cryptographic random number generator (crypto.getRandomValues). Core calculations, such as date math, tax table lookups and unit conversions (on the Korean site), are checked by automated tests against values worked out in advance. When a problem is reported, we check it again and fix it. Mistakes can still slip through, so if you find one, please tell us as described below and we will fix it.

Tools that deal with money and tax

The Korean site's salary, freelancer tax and VAT calculators and its exchange rate tools give reference figures only. Insurance rates, deductions and tax tables can change every year, and exchange rates and fees differ between banks and card issuers. The results are not tax or legal advice. Before an important decision, such as a tax filing or a contract, check the official guidance from the National Tax Service, the National Pension Service and the National Health Insurance Service, or ask a tax accountant.

Tools for fun

The Korean site's name and couple compatibility tools are made for play. Their scores and stories come from fixed rules and have no scientific basis, so please enjoy them lightly.

Advertising

Utilo shows Google AdSense ads so that it can stay free. Ads do not affect the results or anything else a tool shows you. Which ads appear is decided by Google. The privacy policy explains the cookies used for ads and how to turn personalized ads off.

Reporting errors and corrections

If you find a wrong result or an awkward sentence, email us using the address on the contact page. It helps if you include the tool name or page address, what you entered, the result you got, the result you expected, and the device and browser you used. Confirmed errors are fixed on the site, and when a calculation rule changes, the explanation on that tool's page is updated too.