Runtime Support

micro509 is ESM-only, side-effect-free, and uses only WebCrypto APIs.

Compatibility

Runtime	Status	Notes
Node.js	supported	Modern Node with WebCrypto globals (tested on 24+)
Bun	supported	Bun 1.3+
Deno	supported	Requires WebCrypto and web text/base64 globals
Browser	supported	Modern browsers only
Cloudflare Workers	supported	Full WebCrypto available
Edge runtimes	supported	Any runtime with WebCrypto + TextEncoder/TextDecoder + atob/btoa

Requirements

micro509 requires these global APIs:

• crypto.subtle (WebCrypto)
• TextEncoder / TextDecoder
• atob / btoa

No Node.js builtins (crypto, buffer, fs, etc.) are used in library code.

Tree-shaking

micro509 is fully tree-shakeable. Import from domain entrypoints to minimize bundle size:

// Only pulls in verification code
import { verifyCertificateChain } from 'micro509/verify';

// Only pulls in key handling code
import { generateKeyPair } from 'micro509/keys';