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Build Real-time Applications with the new "watch" API in Deno KV
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the absolute minimum to make JSON Web Tokens on deno. Based on JWT and JWS specifications.


After the Compact Serialization process where a web token is represented as the concatenation of:

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

…the finalized JWT looks like this:


Critical Header Parameter (crit)

It supports the Critical Header Parameter like described in the JWS specification.

You can find here an example which includes the crit header parameter.


The API consists mostly of the two functions makeJwt and validateJwt.

You can omit the JWT payload and its claims if you only need the signing and verification feature of the JWS.

makeJwt(headerObject: Jose, claims: Claims | string = “”, key: string)

validateJwt(jwt: string, key: string, throwErrors: boolean = true, criticalHandlers: CritHandlers = {})

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

setExpiration(exp: number | Date): number

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


Try it out with this simple server example:

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

const key = "abc"
const claims = {
  iss: "joe",
  exp: setExpiration(new Date().getTime() + 60_000),
const headerObject = {
  alg: "HS512",
  typ: "JWT",
;(async () => {
  for await (const req of serve("")) {
    if (req.method === "GET") {
      const jwt = makeJwt(headerObject, claims, key)
      req.respond({ body: encode(jwt + "\n") })
    } else {
      const requestBody = decode(await req.body())
      validateJwt(requestBody, key, false)
        ? req.respond({ body: encode("Valid JWT\n") })
        : req.respond({ status: 401, body: encode("Invalid JWT\n") })


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