Can I mine Monero with JavaScript on my own website?

Yes, you can use JavaScript on your own website to run Monero mining code in a browser, often with help from WebAssembly, a way to run compiled code inside a web page. But modern Monero mining is demanding, so a working browser miner is much harder to build—and usually earns much less—than you might expect. If visitors’ devices will do the work, you need their clear permission before mining starts.

What your website would actually do

A browser miner uses the processor, or CPU, in the device that opens your page. It does not use your web server’s processing power just because you own the website.

That means:

• When you open the page on your laptop, your laptop does the mining.
• When a visitor opens it, their device does the mining.
• When the page closes, mining normally stops. Browsers may also pause or slow work in background tabs.

JavaScript can manage the controls and connection. WebAssembly can handle more of the calculations. You would usually also need a connection to a mining pool, a service that combines miners’ work and shares rewards. Many pool connections require a server-side bridge because browsers cannot use the same direct connections as desktop miners.

Why old browser-mining scripts are not enough

Monero has used RandomX, its mining algorithm, since November 30, 2019. An algorithm is the set of rules a miner follows to perform its calculations. Old scripts made for Monero’s earlier CryptoNight algorithms cannot mine today’s Monero unchanged.

RandomX favors CPUs, but it is not lightweight. Its fast mode uses a dataset of about 2,080 MB, plus other memory. Its slower light mode uses a 256 MB cache. Efficient mining also generally needs about 2 MB of L3 cache—a small, fast memory area inside the CPU—per mining thread.

Browsers add their own limits. They cannot offer all the same hardware access and optimizations as native mining software, which runs directly on your computer. WebAssembly helps, but it does not remove those limits.

Before installing any website miner, verify that it actually supports current Monero RandomX. Some services mine another coin and merely pay you in XMR. That is not the same thing.

What this means for everyday devices

On a phone or tablet, mining can drain the battery, heat the device, and cause it to slow down to protect itself. A laptop may develop loud fans, shorter battery life, and sluggish browsing.

For your own test page, start with a low workload and watch temperature and responsiveness. Stop if the device becomes uncomfortable to use.

For visitors, provide:

• An explicit “Start mining” choice, with mining off by default.
• A plain explanation of CPU, electricity, battery, and heat costs.
• A visible stop button and adjustable workload.
• No hidden mining or automatic restart after they stop.

Owning the website does not give you permission to use someone else’s processor. Check applicable local rules too.

The bottom line

You can build a JavaScript-based Monero mining page, but it is better treated as an experiment than dependable website income. Short visits, browser limits, and demanding calculations make earnings uncertain. Measure your actual mining speed and check a live profitability calculator before making promises—and never trust a script that asks for your wallet’s secret recovery phrase.