What Is Coinhive JavaScript Browser Miner And Is It A Virus Or Trojan?

If you’re a regular free bitcoin faucet visitor you’ll have noticed an increasing number of sites attempting to download a JavaScipt file originating from Coinhive to your computer.



Usually, this will send your anti-virus software beserk and will prompt a warning message referring to a ‘malicious page attempting to download malware’ originating from Coinhive.

Most of the time you’ll be give the option to either allow or block this download and, if you’re not familiar with it, the majority of people will choose the latter and promptly leave the site where it appeared.

The warning message will resemble the following depending on your anti-virus software:

Alert: This is the warning Kaspersky throws up when Coinhive attempts to activate.

But this download is in fact not a virus or trojan but a small, harmless piece of code that allows your computer to tap into Coinhive’s JavaScript Monero miner. Downloading it will not harm your computer.

Note: Coinhive has been abused by malware developers who have embedded it in certain popular software products and websites. Effectively this is a form of cybersquatting or cryptojacking designed to earn free coins for the culprits. But this is different to its use in faucets and microwallets.

We’ve deliberately omitted an example on this page because it would trigger the same warning on your PC and you might be tempted to click away! However, you can see Coinhive in action on our browser mining guide page.

You’ll need to allow the JavaScript download but mining will not start automatically – there is widget box on the page that you have to click to manually start the mining process so you can see it in action.


Like our browser mining guide page, most bitcoin faucets that featuring mining, such as Moon Bitcoin, require you to agree to the download before you can mine.

The benefits if you do on the Moon faucet is that you will accrue a bonus of up to 100% of your claim value depending on how long you have left the miner running for.

The hugely popular Free Bitcoin faucet and earnings site also features browser mining, but here your earnings are added in denominations of Satoshi (fractions of bitcoin) to your coin pot.

This is the opt-in menu option on Moon Bitcoin:


Generous bonuses: You can earn up to an extra 100% of your Moon Bitcoin claim by allowing the browser miner to run.

Moon Bitcoin pays into the CoinPot microwallet (this is the direct mining link) which also features browser mining. Here, you can mine Bitcoin, Bitcoin Cash, Litecoin, Dogecoin and Dash which are automatically added to you balances within around five minutes. The Faucethub microwallet also offers a similar feature.

We should point out that in all these cases you aren’t technically mining these different coins, you are in fact mining the Monero cryptocurrency which is then converted into the coin of your choice.

The reason for this, and it gets a bit technical here, is that Coinhive uses the Monero blockchain because it calculates hashes with an algorithm called Cryptonight.

This is optimised to run well on consumer CPUs putting it in reach of the average user, unlike coins such as bitcoin and litecoin which can only be profitably mined using specialist equipment known as Application-specific integrated circuit (ASIC) miners.


Monetising Content

Many site owners see browser mining as a way of monetising their content in addition to advertising. However, many consumers are unhappy at this development and there has been a backlash against websites using the Coinhive script.

This came to the public fore when it was discovered that file-sharing website The Pirate Bay was surreptitiously harnessing the power of its visitors’ CPUs to mine coins using Coinhive.

Since then Coinhive has spread like wildfire across a wide range of other websites as developers experiment with ways to increase their earnings.

Huge Potential

While most websites have the courtesy to ask your permission to use your spare processing power to mine, some do not. This means that you only realise it’s happening when your CPU fan goes into overdrive and your computer grinds to a halt.

It is these sites in particular that have annoyed visitors, especially as there are concerns that the mining software could damage computer hardware if left running for extended periods of time.

That said, Coinhive has huge potential for both financially supporting websites and staging charitable campaigns. As long as webmasters are up front with visitors and don’t automatically opt them in to mining there is no reason why it can’t be an effective monetisation tool.

Useful links:

Browser Mining Guide

General Mining Guide

Moon Bitcoin Review

Is CoinPot Microwallet Legitimate

Complete Faucet List

Top Faucet List