Sync and Async APIs

The X.509 entrypoint combines synchronous DER/PEM helpers with operations backed by WebCrypto. Async functions return a Promise and must be awaited; sync functions return their value or Result directly.

Execution model

Functions	Timing	Why
parseCertificate*, parseCertificateSigningRequest*	sync	Pure PEM/DER decoding
parseCertificateChainPem	sync	Pure PEM/DER decoding
encode*, build*, decode*, findExtension, and name text helpers	sync	Pure transformation of in-memory data
certificateFingerprint	async	WebCrypto digest
createCertificate, createSelfSignedCertificate	async	WebCrypto key export, key generation, and signing
createCertificateSigningRequest	async	WebCrypto key export and signing
getSubjectPublicKey, getSubjectPublicKeyOrThrow	async	WebCrypto key import
certificateMatchesPrivateKey, matchCertificatePrivateKey	async	WebCrypto key derivation and export

Every other function exported from micro509/x509 is synchronous.

Await the operation, not the Result

parseCertificatePem(pem) returns a ParseCertificateResult immediately. JavaScript permits await parseCertificatePem(pem), but the await has no effect.

certificateFingerprint(pem) returns a Promise<CertificateFingerprint>. In untyped JavaScript, destructuring it without await reads the Promise object, so colonHex is undefined. TypeScript rejects that destructuring when the library types are intact.

const parsed = parseCertificatePem(pem); // ParseCertificateResult, available now
const fingerprint = await certificateFingerprint(pem); // CertificateFingerprint