Fast, quite and beautiful messages for validating schema

Usage no npm install needed!

<script type="module">
  import jsonMsg from 'https://cdn.skypack.dev/json-msg';



json-msg is a lightweight alternative for Joi or Yup or any json validator. Unlike Joi, json-msg only focus on error messages and validations

json-msg documentation


  • Customizable Messages
  • Custom Validation
  • Easy Configuration
  • Lightweight 4.6kb
  • Fast
  • No Dependencies



npm i json-msg


<script src="https://unpkg.com/json-msg"></script>

UNPKG Unbabel version - 4.6kb (IE not supported)

<script src="https://unpkg.com/json-msg/dist/jm.unbabel.min.js"></script>


import jm "json-msg";

const schema = {
  username: jm.str(),
  password: jm.num()
  confirmPassword: jm.sameAs("password")

const data = {
  username: "cris123",
  password: 123456,
  confirmPassword: 123456,

Complex Validation

import jm "json-msg";

const { str , bool, num, array , sameAs} = jm;

const userSchema = {
  id: num({min: 1000, max: 100000}),

  username: str({ min: 6,alphanum: true }),

  pass: str({ min: 6, label: "Password"  }),

  confirmPass: sameAs("pass",{label: "Confirm Password"}),

  age: num({min: 15}),

  gender: str({ required: false, allow: [null] }),

  hobbies: array({ items: str()})

  address: {
    city: str({ min: 1000 }),
    country: str({required: false})

const userData = {
  id: 5000,
  username: "darkcris1",
  pass: "loremIpsum",
  age: 20,
  confirmPass: ""
  gender: null,
  hobbies: ["gaming", "coding", "solving"]
  address: {
    city: "Davao City",

// if abortEarly is false, all the data properties errors will show

// if showALlErrors is true will give you an array of error messages on that specific errors

jm.validate(userData,userSchema,{abortEarly: false, showAllErrors: true})