How to Securely Encrypt Files in Your Browser with Hat.sh

Hat.sh is a free, open-source web application that provides secure, local file encryption directly inside your web browser.

Because it operates entirely client-side using libsodium, your files are never uploaded to a remote server. All processing happens locally on your machine, ensuring total data privacy. The app utilizes advanced cryptographic standards like XChaCha20-Poly1305 for symmetric encryption and Argon2id for password-based key derivation. Step-by-Step Guide: How to Encrypt a File Follow these steps to safely lock your sensitive data:

Open the App: Navigate to the official site or your self-hosted instance of Hat.sh.

Upload the File: Drag and drop your target file into the workspace, or click Browse File to select it manually.

Choose Encryption Method: Select whether you want to use a standard Password or an asymmetric Public Key.

Enter a Passphrase: Type a strong, unique password. You can also click the built-in generator to automatically create a secure random password.

Encrypt and Save: Click the Encrypt button. The app will instantly process the file locally and prompt you to download the encrypted .enc file to your computer. Step-by-Step Guide: How to Decrypt a File

To unlock your file and regain access to the original data, follow these actions:

Upload the Encrypted File: Open Hat.sh and select the .enc file you want to unlock.

Provide the Key: Enter the exact password or upload the private key used during the encryption phase. Decrypt: Click the Decrypt button.

Download: Save the freshly decrypted, original file back to your device storage. Core Security Features

Zero-Knowledge Privacy: No files, analytical data, or passwords ever leave your browser or get saved to an external database.

High Memory Efficiency: Using browser Service Workers, Hat.sh encrypts large items in small chunks rather than loading the whole file into RAM at once. This prevents your browser from crashing, even with files larger than 25GB.

Offline Functionality: You can download the tool source from the Hat.sh GitHub Repository to self-host and run it entirely offline for maximum security. If you want to customize your setup, let me know:

Are you interested in using asymmetric public/private keys instead of text passwords?

Do you need to know about browser file size limitations on mobile or Safari?

Hat.sh – Encrypt and Decrypt files securely in your browser.