@molecule/api-jwt

Auto-generated, AI-first package reference for the molecule.dev ecosystem. It is written to be read by coding agents as much as by people, and is generated from this package's source — edit src/index.ts JSDoc, not this file.

JWT interface for molecule.dev.

Provides an abstract JWT interface that can be backed by any JWT library. Use setProvider to provide a concrete implementation such as @molecule/api-jwt-jsonwebtoken.

Quick Start

import { sign, verify, decode } from '@molecule/api-jwt'

const token = sign({ userId }, { expiresIn: '15m' }) // server-side; expiry set

try {
  const claims = verify(token) as JwtPayload // signature CHECKED — safe to trust
  grantAccess(claims.userId)
} catch {
  res.status(401).json({ error: 'Invalid or expired token.' })
}

decode(token) // NOT verified — never use its output for an auth decision

Type

core

Installation

npm install @molecule/api-jwt @molecule/api-bond

API

Interfaces

JwtDecodeOptions

Options for decoding a JWT (without verification).

interface JwtDecodeOptions {
  complete?: boolean
  json?: boolean
}

JwtPayload

Decoded JWT payload.

interface JwtPayload {
  [key: string]: unknown
  iss?: string
  sub?: string
  aud?: string | string[]
  exp?: number
  nbf?: number
  iat?: number
  jti?: string
}

JwtProvider

JWT provider interface that all JWT bond packages must implement.

Provides sign, verify, and decode operations. Key management and algorithm configuration are handled by the core package.

interface JwtProvider {
  sign(payload: JSONObject, options?: JwtSignOptions, privateKey?: string | Buffer): string

  verify(
    token: string,
    options?: JwtVerifyOptions,
    publicKey?: string | Buffer,
  ): string | JwtPayload

  decode(token: string, options?: JwtDecodeOptions): string | JwtPayload | null
}

JwtSignOptions

Options for signing a JWT.

interface JwtSignOptions {
  algorithm?: JwtAlgorithm
  expiresIn?: number | string
  notBefore?: number | string
  audience?: string | string[]
  issuer?: string
  subject?: string
  jwtid?: string
  keyid?: string
  header?: Record<string, unknown>
}

JwtVerifyOptions

Options for verifying a JWT.

Note: security-hardened bonds (e.g. @molecule/api-jwt-jsonwebtoken) REFUSE to honor ignoreExpiration/ignoreNotBefore — an expired token always fails verification regardless of these flags. To tolerate clock skew or slow flows, use clockTolerance (seconds) instead.

interface JwtVerifyOptions {
  algorithms?: JwtAlgorithm[]
  audience?: string | string[]
  issuer?: string | string[]
  subject?: string
  clockTolerance?: number
  maxAge?: string | number
  complete?: boolean
  ignoreExpiration?: boolean
  ignoreNotBefore?: boolean
}

Types

JSONObject

A plain JSON object whose values are JSONValues. Used as the payload type for JWT signing operations.

type JSONObject = { [key: string]: JSONValue }

JSONValue

Recursive JSON value type representing any valid JSON primitive, array, or object.

type JSONValue = string | number | boolean | null | JSONValue[] | { [key: string]: JSONValue }

JwtAlgorithm

Supported JWT signing algorithms.

type JwtAlgorithm =
  | 'RS256'
  | 'RS384'
  | 'RS512'
  | 'HS256'
  | 'HS384'
  | 'HS512'
  | 'ES256'
  | 'ES384'
  | 'ES512'
  | 'PS256'
  | 'PS384'
  | 'PS512'

Functions

decode(token, options)

Decodes a JWT string without verifying its signature. Useful for inspecting token contents when verification is handled elsewhere.

function decode(token: string, options?: JwtDecodeOptions): string | JwtPayload | null

• token — The JWT string to decode.
• options — Decode options such as complete for full header+payload output.

Returns: The decoded payload, or null if the token cannot be decoded.

generateKeyPairSync()

Generates an RSA-2048 key pair in PEM format for JWT signing and verification.

function generateKeyPairSync(): { publicKey: string; privateKey: string }

Returns: An object containing publicKey and privateKey as PEM strings.

getProvider()

Retrieves the bonded JWT provider, throwing if none is configured.

function getProvider(): JwtProvider

Returns: The bonded JWT provider.

hasProvider()

Checks whether a JWT provider is currently bonded.

function hasProvider(): boolean

Returns: true if a JWT provider is bonded.

setProvider(provider)

Registers a JWT provider as the active singleton. Called by bond packages during application startup.

function setProvider(provider: JwtProvider): void

• provider — The JWT provider implementation to bond.

sign(object, options, privateKey)

Signs a payload into a JWT string using the bonded provider. Uses the configured algorithm, expiry, and private key as defaults.

function sign(
  object: JSONObject,
  { algorithm = JWT_ALGORITHM, expiresIn = JWT_EXPIRES_TIME, ...rest }?: JwtSignOptions,
  privateKey?: string | Buffer<ArrayBufferLike>,
): string

• object — The JSON payload to sign.
• options — Signing options; algorithm defaults to JWT_ALGORITHM, expiresIn defaults to JWT_EXPIRES_TIME.
• options.algorithm — The signing algorithm (e.g. RS256, HS256).
• options.expiresIn — Token lifetime in seconds.
• privateKey — The private key for signing; defaults to JWT_PRIVATE_KEY.

Returns: The signed JWT string.

verify(token, options, publicKey)

Verifies a JWT string and returns the decoded payload. Uses the configured algorithm and public key as defaults.

function verify(
  token: string,
  { algorithms = [JWT_ALGORITHM], ...rest }?: JwtVerifyOptions,
  publicKey?: string | Buffer<ArrayBufferLike>,
): string | JwtPayload

• token — The JWT string to verify.
• options — Verification options; algorithms defaults to [JWT_ALGORITHM].
• options.algorithms — The allowed signing algorithms for verification.
• publicKey — The public key for verification; defaults to JWT_PUBLIC_KEY.

Returns: The decoded payload string or object.

writeKeys(outputPath)

Writes a freshly generated RSA key pair to disk as PEM files. Creates the output directory if it does not exist.

function writeKeys(outputPath?: string): void

• outputPath — Directory to write the PEM files into; defaults to {JWT_KEYS_DIR}/{NODE_ENV}/.

Constants

JWT_ALGORITHM

The signing algorithm used for JWT operations. Read from the JWT_ALGORITHM environment variable, defaulting to RS256. An unrecognized value logs an actionable warning at module load and falls back to RS256 rather than failing every sign()/verify() call later with an unexplained "invalid algorithm" error.

const JWT_ALGORITHM: JwtAlgorithm

JWT_EXPIRES_TIME

Token lifetime in seconds. Read from the JWT_EXPIRES_TIME environment variable, defaulting to 604800 (1 week).

const JWT_EXPIRES_TIME: number

JWT_PRIVATE_KEY

The RSA private key for signing JWTs. Read from the JWT_PRIVATE_KEY environment variable, or loaded from the PEM file on disk.

Throws at startup if neither source provides a key — running with an empty secret would allow anyone to forge valid JWTs.

const JWT_PRIVATE_KEY: string | Buffer<ArrayBufferLike>

JWT_PUBLIC_KEY

The RSA public key for verifying JWTs. Read from the JWT_PUBLIC_KEY environment variable; when only JWT_PRIVATE_KEY is set, the matching public key is DERIVED from it (a disk fallback could not match an env-provided private key and would make every signed token fail verification); otherwise loaded from the PEM file on disk.

Throws at startup if no source provides a key.

const JWT_PUBLIC_KEY: string | Buffer<ArrayBufferLike>

JWT_REFRESH_TIME

Refresh window in seconds — tokens are refreshed if they will expire within this period. Read from the JWT_REFRESH_TIME environment variable, defaulting to 3600 (1 hour).

const JWT_REFRESH_TIME: number

Available Providers

Provider	Package
JWT signing keys	@molecule/api-jwt-jsonwebtoken

Injection Notes

Requirements

Peer dependencies:

• @molecule/api-bond ^1.0.1

Runtime Dependencies

• @molecule/api-bond

{@link verify} is the ONLY way to trust a token — {@link decode} does NOT check the signature. Never make an auth decision from decode(): an attacker can forge any payload that decode() will happily return. Use verify() (it throws — catch it) for anything security-relevant; decode() is only for reading a token you do NOT trust.

• The signing key (private key / secret) is SERVER-SIDE only — never ship it to the browser. Only an asymmetric PUBLIC key may be published.
• A JWT payload is READABLE by anyone (base64, not encrypted) — never put a password, secret, or sensitive PII in it.
• Always set + honor expiry ({@link JWT_EXPIRES_TIME}); a non-expiring token can't be revoked.
• In a molecule app auth is ALREADY wired: the global verifyMiddleware verifies the JWT and populates res.locals.session, so a handler calls getUserId(res) — do NOT call verify()/sign() by hand for the session (see the auth skill). Use these directly only for a CUSTOM token, e.g. a signed email/reset link.
• Re-signing decoded claims (refresh flows): strip exp/iat first. sign() always sets expiresIn (default {@link JWT_EXPIRES_TIME}), and the underlying library throws (Bad "options.expiresIn" option the payload already has an "exp" property) when the payload still carries the old exp — so const { exp, iat, ...claims } = verify(oldToken) as JwtPayload; sign(claims) is the correct refresh shape.
• Set JWT_PRIVATE_KEY and JWT_PUBLIC_KEY together (or neither). If only the private key is set, the matching public key is DERIVED from it automatically; setting only the public key is for verify-only deployments.
• When neither key env var is set, a key pair is auto-generated on disk at {JWT_KEYS_DIR}/{NODE_ENV}/ — default JWT_KEYS_DIR: process.cwd() + '/.keys', a stable app-level directory (NOT inside node_modules, so npm ci/reinstall never wipes it). Set JWT_KEYS_DIR to relocate it (e.g. a persistent volume in production). A pre-existing pair at the legacy node_modules-relative location is migrated forward automatically (with a logged warning) instead of being silently regenerated.
• JWT_ALGORITHM (default RS256) is validated at module load against the {@link JwtAlgorithm} union; an unrecognized value (e.g. a typo like rs256) logs an actionable warning and falls back to RS256 instead of failing every sign()/verify() call later with an opaque "invalid algorithm" error.