Automated HTML validation tool

Usage no npm install needed!

<script type="module">
  import valimate from '';



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Valimate is a configurable command line interface for validating local and remote websites against the Nu HTML Checker. It can be easily integrated with continuous integration pipelines and regression test suites.

Requires Node.js 10 or greater


npm i --save-dev valimate


Valimate is configured on a per-project basis via the valimate.json file. This must reside in the root directory of your project. A simple configuration might look like this:

  "urls": [

To validate these URLs, run npx valimate in your terminal or valimate within the context of an npm script. Valimate will read the config; each URL is requested via HTTP GET, and the returned markup is sent to the Nu validator.

All of the configuration options are listed on the valimate.json wiki page.

Running with another configuration file

Run npx valimate file.json in your terminal or valimate file.json within the context of an npm script.

Running against a local app server

In a continuous integration scenario, it could be ideal validate your app server with the latest code changes. If this server is developed in Node.js, then you can use the Valimate Notifier module to defer the execution of tests until the server has started up and is ready to serve HTML.

In the valimate.json file, set the localAppServer to point to your server's entry script. You can also use the env property to pass environment variables to the process as key-value pairs:

  "localAppServer": {
    "entryPoint": "app.js",

    "env": {
      "TEST": "true"

  "urls": [

Then use the Valimate Notifier module to notify Valimate when the server is ready to be validated. The module exports a fuction which accepts one argument; a truthy value suggests that start up was successful, whereas a falsy value suggests failure, causing Valimate to exit:

'use strict';

const http = require('http');
const notifyValimate = require('valimate-notifier');
const dataService = require('./services/myDataService');
const htmlBuilder = require('./view/htmlBuilder');

const PORT = 8081;

dataService.someAsyncOperation().then(data => {
  http.createServer((req, res) => {
    res.end(htmlBuilder(data), 'utf-8');
  }).listen(PORT, () => {
}).catch(e => notifyValimate(false));

Upon running the valimate CLI, your app server will be started as a child process, and killed when testing is complete.

If your app server has not been started by Valimate (e.g. running in production), then this method will do nothing.

Programmatic Use

Valimate can also be imported into your Node.js scripts as a CommonJS module. It exposes the validate method, which takes the config as a parameter of the Object type. This returns a Promise which resolves once the URLs have been validated. A Boolean is passed through the chain that will be true if the markup is invalid, or false if it is valid.

'use strict';

const valimate = require('valimate');

const config = {
  urls: [

/* protip: ~ = bitwise NOT - can use this twice to doubly
 * invert the bits to coerce a bool to 1 or 0 */
  .then(isInvalid => process.exit(~~isInvalid));

Using Valimate programmatically will still print results as if the library had been invoked via the CLI; this capability is simply a means of convenience; this can be useful when there are many asynchronous prerequisites involved. In the next major release, however, this may directly expose validation results.


See the Contributing wiki page.