4People brings together more than 100 free online tools for development, study and work, at 4people.lucasbittencourt.dev. Everything runs in the browser: what you type isn't sent to any server. It works without an account and is in beta; the app is in Portuguese.
What it does
- Generators and validators for Brazilian documents (CPF, CNPJ, RG, CNH, PIS, RENAVAM, voter ID), license plates, test credit cards (with a custom BIN and CSV and JSON export), passwords, UUIDs, names and fictional people.
- Development: JWT generator and decoder, regex, XPath and JSONPath testers, a REST API tester, timestamp converter, cron describer and text diff.
- Converters: JSON, YAML, XML, INI and CSV to SQL, Base64, URL, HTML, number bases, colors, units (length, mass, temperature, area, volume and more) and live currency exchange rates.
- Networking: IPv4 and IPv6 subnet calculators, SLA, download time, my IP and Brazilian postal code (CEP) lookup.
- Math: percentages, rule of three, compound interest, quadratic equations, GCD and LCM, Roman numerals with no upper limit, areas and date calculations.
- Installable as an app (PWA), and pages already opened work offline.
Privacy
Calculations happen on your device. There's no account, no ads, no cookies and no visit statistics. Only a few tools query public services, such as postal codes, banks, IP and exchange rates. The details are in the Privacy policy and the End user license agreement (EULA), and the source code is public.