How we calculate

The text and encoding tools share one engine, a single JavaScript file that is covered by unit tests and also runs at build time to print the example result you see before you type. Each page states the rule the tool applies and shows a worked example you can check by hand.

Text and bytes

Encoders work on UTF-8 bytes, the encoding the web uses. A character outside ASCII, such as é or an emoji, becomes two to four bytes, and the hex, binary and Base64 tools show every one of them.

Counting

Characters are counted as Unicode code points, so an emoji counts once. Words are runs of characters separated by white space. Each counting tool lists its own rules next to the result.

Randomness

UUIDs and other random values come from the browser's Web Crypto API (crypto.getRandomValues), not from Math.random().

Standards

Where a format is defined by a standard, the tool follows it and the page links to it: RFC 4648 for Base64, RFC 3986 for URL encoding, RFC 9562 for UUIDs, the Unicode Standard for styled text.

Outside data

A small number of tools fetch data from another service: exchange rates, crypto prices, synonyms and IP address details. Those pages name the service, show when the data was fetched, and are listed on the privacy page. No rate or price is built into a page.

Where the calculation happens

In your browser. The page downloads the tool once and does the work on your device, so results appear as you type and your inputs are not sent to us.

What a tool page shows

The date the page was last updated.
How the result is produced.
On the tools rebuilt on our current template: the formula or rule, a worked example you can check by hand, and the sources the numbers come from, linked. Older tools are being brought up to that standard.

Sources we rely on

Limits

tools.best provides utilities for convenience. Check a result before you rely on it in production, in print or in a transaction. Exchange rates and crypto prices come from third-party services, can be delayed, and are not the rate a bank or exchange will give you.