How these tools are built
What runs where, where the methods come from, and what these tools deliberately will not do.
Everything runs on your device
There is no server-side processing anywhere on this site. When you paste text into an extractor or click colonies on a plate, the calculation happens in your browser using your own hardware. Nothing is transmitted, logged, or retained after you close the tab.
This is verifiable rather than a promise. Load any tool page, disconnect from the internet, and the tool keeps working. If it needed a server, it could not.
What that rules out
The same architecture that removes the upload also sets a hard limit, and it is worth being straight about it. Any tool that genuinely requires a live lookup against someone else's database cannot be built this way.
Checking whether a VAT number is actually registered needs a query to a tax authority. Confirming a bank account exists needs access to licensed reference data. Tools like that are not offered here, because the version that could be built - one that checks the format looks plausible and nothing more - would answer a different question than the one people are asking.
Where the methods come from
Each tool page includes a section explaining the method it uses: the formula, the convention, or the reference table. Where a figure comes from a specific standard or authority, the page names it.
Where a result is an estimate rather than an exact answer, the page says so in the tool itself, not buried in a footnote. Presenting a heuristic as a precise formula is the most common failure of tools like these, and it is the one we most want to avoid.
What we will not build
- Generators for national identity or tax numbers. Validators are useful; generators are identity-fraud tooling.
- Anything that locates a person from a plate, phone or account.
- Media downloaders.
- Medical dosage or symptom tools. Getting these wrong causes real harm and no amount of traffic justifies the risk.
Reporting an error
If a tool gives a wrong answer, we want to know, and a specific report is far more useful than a general one. The input you used, the result you got, and the result you expected is enough to reproduce almost anything.
There are currently 795 tools here, with more added regularly. Categories that are planned but not yet built are listed on the all tools page rather than shown as empty pages.