About UsefulDevTools

Who We Are

UsefulDevTools is owned and operated by Online Mega Stores Zbigniew Orlowski, a registered sole proprietorship based in Poland. The site is built and maintained by Zbigniew Orlowski, a web developer who has spent years building and running online projects, and who created this site out of a simple frustration: the everyday utilities developers reach for were scattered across dozens of cluttered, ad-heavy websites that often uploaded your data to a server just to reverse a string or merge two PDFs.

We are not a venture-backed startup or a large content farm. This is an independently run project, and every tool published here is built, tested and maintained by hand.

What We Do

The site brings together more than a thousand pages of free, browser-based utilities organised into four main areas:

• Text tools — comma separators, splitters, joiners, case converters, duplicate removal, character and word counters, text metrics and reading-time analysis.
• Calculators and converters — financial calculators (loans, mortgages, APR, retirement, tax), structural engineering calculators (beams, columns, footings, wind loads), construction material estimators, biology and laboratory calculators, veterinary dosage tools, and unit converters for length, weight, volume and temperature.
• PDF tools — merge, split, compress, rotate, crop, protect, unlock, watermark and convert PDF documents to and from Word, Excel, PowerPoint, images and text.
• Developer tools — JSON, XML, YAML and CSV converters, SQL and code formatters, an API tester, a webhook tester, security and dependency scanners, plus a large library of ready-to-copy UI components in HTML, CSS, Tailwind and React.

Our Approach to Your Data

Almost every tool on this site runs entirely in your browser using JavaScript. When you paste text into a formatter or drop a PDF into the merge tool, that content is processed on your own device and is never transmitted to us. We cannot see it, we do not store it, and it does not appear in any log.

A small number of tools genuinely require server-side processing — most notably the Office document conversions, which need a conversion engine that cannot run in a browser. Where this is the case, we say so on the tool itself, and uploaded files are processed and discarded rather than retained. Full details of what we collect and why are set out in our Privacy Policy and Cookie Policy.

How the Site Is Funded

Every tool on UsefulDevTools is free to use, with no account required and no paywall. The site is funded through advertising and voluntary contributions from users who find it useful. Advertising never dictates our content: we do not accept payment to rank a tool higher, and the calculators return the numbers the mathematics gives, whatever they are.

Accuracy and Limitations

We take accuracy seriously, and calculators are checked against published formulas, engineering standards and worked examples before release. That said, the tools here are intended for education, estimation and preliminary planning. Structural, financial, medical and veterinary calculations in particular should always be verified by a qualified professional before you act on them. Each tool carries a disclaimer explaining its limitations, and we would rather you double-check a result than trust it blindly.

If you spot an error, we genuinely want to hear about it. Every tool has a feedback button, and corrections are prioritised over new features.

Company Details

Get in Touch

Questions, bug reports, tool requests and business enquiries are all welcome. You can reach us through the contact page, or by email at hello@usefuldevtools.com. We read everything and reply to as much as we can.