What J-Kit is
J-Kit is a catalog of 300+ online tools for developers, designers, finance, legal and health professionals, and anyone who needs to solve a one-off technical task. It brings calculators, converters, generators, validators and network/text utilities together in one place, each with an explanation of what it does and how the result is produced.
The priority is to solve small tasks quickly, with no signup and without turning the tool into a sales funnel. Each tool has its own page in Portuguese and English, with context, examples and frequently asked questions.
Who operates it
J-Kit is maintained by J-Kit, an independent software project focused on useful, well-documented tools. It is not professional advice nor the service of a specific individual, it is an ongoing editorial and technical product. Questions, corrections and partnerships can be sent to [email protected].
How the tools are built and verified
Each tool is implemented with its logic isolated and covered by automated tests. The formulas, algorithms and standards used in the calculation are described on the tool page, and reference sources (laws, official tables, technical standards and APIs) are cited whenever the result depends on them.
Values that change over time, economic indices, tax tables, official rates, are refreshed from official sources and pass staleness checks, to reduce the risk of a calculation silently going out of date. Each page shows when it was last updated.
Sources, accuracy and limits
Results are educational estimates. For decisions with legal, tax, medical or financial impact, confirm with a qualified professional and the official source. If you find a result that looks wrong, let us know at [email protected] with the inputs you used, we review and fix it.
Product principles
Whenever possible, processing happens in the browser, your data does not leave your device. When a tool needs network or API access, that is indicated on the tool page itself.
Monetization may exist, but the widget comes first. Ads do not appear in embeds, do not live inside tools and should not cause meaningful layout shifts.