A simple, client-side tool to encrypt or decrypt text with a passphrase, using the age encryption tool. Everything runs locally in your browser after the page loads, and age makes brute-forcing the passphrase deliberately slow and impractical.
Auditing this page: this is a single HTML file with one external dependency, the age-encryption library, loaded from a CDN. View the source to see exactly what it does. All encryption and decryption run locally in your browser, nothing you type is sent anywhere. You can confirm this yourself: open your browser's developer tools, watch the network tab, and check that no requests go out while you encrypt or decrypt.