Capsule
An open standard for secure, client-side article encryption
Easy & Fast
Simple integration with any web stack. Pre-encrypt content at build time, decrypt instantly in the browser.
Secure by Design
Uses Web Crypto API with envelope encryption. Private keys never leave the browser, stored with extractable: false.
Open Standard
Language-agnostic specification. Implement in any language—Node.js, PHP, Python, or Go.
No Dependencies
Works independently of CMS, authentication, or permission systems. Pure encryption, nothing else.
How It Works
1
Pre-encrypt Content
Server encrypts articles with AES-256-GCM keys per subscription tier
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2
Embed in HTML
Encrypted content embedded in page, works offline and with caching
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3
Key Exchange
Browser sends public key, receives wrapped decryption key
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4
Decrypt Locally
Client decrypts content using cached keys, even offline