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The absolute minimum to make JSON Web Tokens in deno. Based on JWT and JWS specifications.

This library is accessible through the service.


To generate JWTs which look in their finalized form like this (with line breaks for display purposes only)


… we use the mandatory compact serialization process where a web token is represented as the concatenation of

'BASE64URL(UTF8(JWS Protected Header))' || '.' || 'BASE64URL(JWS Payload)' ||'.'|| 'BASE64URL(JWS Signature)'.

Cryptographic Algorithm

HMAC SHA-256 (“HS256”), HMAC SHA-512 (“HS512”) and none (Unsecured JWTs) of the signature and MAC algorithms defined in the JSON Web Algorithms (JWA) specification have been implemented already. But more shall come soon.

Expiration Time

The optional exp claim identifies the expiration time on or after which the JWT must not be accepted for processing. This library checks if the current date/time is before the expiration date/time listed in the exp claim.

Critical Header

This library supports the Critical Header Parameter crit which is described in the JWS specification here.

Look up this example to see how the crit header parameter works.


The API consists mostly of the two functions makeJwt and validateJwt, generating and validating a JWT, respectively.

makeJwt({ header: Jose, payload?: Payload }, key: string): string

The function makeJwt returns the url-safe encoded JWT.

In cases where you only need the signing and verification feature of the JWS, you can omit the payload.

validateJwt(jwt: string, key: string, isThrowing: boolean = true, critHandlers?: Handlers): Promise

The function validateJwt returns a promise which - if the JWT is valid - resolves to a JWT representation as JavaScript object: { header, payload, signature }. If the Jwt is invalid the promise resolves to null or an Error is thrown - depending how you set the boolean isThrowing.

setExpiration(exp: number | Date): number

Additionally there is the helper function setExpiration which simplifies setting an expiration date.

// A specific date:
setExpiration(new Date("2020-07-01"))
// One hour from now:
setExpiration(new Date().getTime() + 60 * 60 * 1000)


Try djwt out with this simple server example:

The server will respond to a GET request with a newly created JWT.
On the other hand, if you send a JWT as data along with a POST request, the server will check the validity of the JWT.

import { serve } from ""
import { encode, decode } from ""
import validateJwt from ""
import makeJwt, {
} from ""

const key = "your-secret"
const payload: Payload = {
  iss: "joe",
  exp: setExpiration(new Date().getTime() + 60000),
const header: Jose = {
  alg: "HS256",
  typ: "JWT",

console.log("server is listening at")
for await (const req of serve("")) {
  if (req.method === "GET") {
    const jwt = makeJwt({ header, payload }, key)
    req.respond({ body: encode(jwt + "\n") })
  } else {
    const requestBody = decode(await Deno.readAll(req.body))
    await validateJwt(requestBody, key, false)
      ? req.respond({ body: encode("Valid JWT\n") })
      : req.respond({ body: encode("Invalid JWT\n"), status: 401 })


Every kind of contribution to this project is highly appreciated.


  1. Add more optional features from the JWT and JWS specifications
  2. Make more tests