This FAQ covers the history, operation, legal issues, and current status of Coinhive, the infamous cryptocurrency mining script that used website visitors' CPUs. It aims to provide clear, factual answers to common questions about this controversial technology.

What was Coinhive?

Coinhive was a JavaScript-based cryptocurrency miner that ran in web browsers, using visitors' CPU power to mine the Monero cryptocurrency without their explicit consent. Launched in September 2017, it was designed as an alternative to online advertising, allowing website owners to earn revenue by having visitors' devices perform mining computations. However, it quickly became associated with malicious use, as many websites integrated it without disclosing it to users, leading to widespread criticism and legal actions.

Coinhive's service was officially shut down in March 2019, but its legacy persists in the form of similar scripts and the ongoing debate over browser-based mining.

How did Coinhive work?

Coinhive operated by embedding a JavaScript code snippet into a website's HTML, which then ran in the background of a visitor's browser. The script used the device's CPU to solve complex cryptographic puzzles for the Monero blockchain, and the resulting mining rewards were sent to the website owner's wallet. The mining process was resource-intensive, often causing noticeable CPU spikes and reduced device performance.

Website owners could customize the mining intensity and choose whether to display a captcha or other user consent mechanisms, but many chose to run it silently. Coinhive provided an API and dashboard for tracking earnings, making it easy for even non-technical users to integrate.

Why was Coinhive controversial?

Coinhive was highly controversial because it was frequently deployed without user consent, effectively hijacking visitors' computing power for financial gain. This practice, known as cryptojacking, raised serious ethical and legal concerns, including privacy violations, unauthorized use of resources, and potential damage to users' devices.

Many antivirus programs and browser extensions flagged Coinhive as malware, and several websites were caught using it in secret. This led to public backlash, legal actions, and widespread condemnation from the cybersecurity community.

Is Coinhive still active in 2026?

No, Coinhive is not active in 2026; its service was permanently shut down on March 8, 2019. The domain and infrastructure were taken offline, and the project's operators announced the closure in a statement, citing the current market conditions and the negative perception of the project.

However, the code and concepts behind Coinhive have been replicated by other projects, and some websites still attempt to run similar mining scripts. Additionally, the term "Coinhive" is often used generically to describe any browser-based cryptocurrency miner, even though the original service no longer exists.

What happened to Coinhive after it shut down?

After Coinhive shut down, its code was open-sourced, allowing others to use and modify it. However, the shutdown did not end browser-based mining; instead, it led to the emergence of alternative mining scripts and services. Some of these attempted to operate more transparently, requiring user consent, while others continued the malicious practice of cryptojacking.

The shutdown also prompted increased awareness and development of anti-cryptojacking measures in browsers and security software. For example, Google Chrome introduced features to block aggressive mining scripts, and various browser extensions were developed to detect and prevent unauthorized mining.

What are the legal implications of using Coinhive?

Using Coinhive or similar scripts without user consent is illegal in many jurisdictions, as it constitutes unauthorized use of computing resources and may violate computer fraud and privacy laws. Several individuals and companies have faced lawsuits and criminal charges for deploying Coinhive without disclosure.

For example, in the United States, the Federal Trade Commission has taken action against websites for deceptive practices related to cryptojacking. In other countries, such as Japan, the use of Coinhive without consent was explicitly deemed a criminal offense. Website owners should always obtain explicit, informed consent from users before running any mining scripts.

What are the pros and cons of Coinhive?

Coinhive had both potential benefits and significant drawbacks. The primary advantage was that it offered a new revenue stream for website owners, potentially reducing reliance on intrusive ads. It also allowed for micro-transactions without traditional payment systems.

However, the cons far outweighed the pros for most users:

  • Resource Drain: Mining consumed substantial CPU power, slowing down devices and increasing electricity bills.
  • Privacy Concerns: Users were often unaware that their devices were being used for mining.
  • Malware Association: Coinhive was frequently bundled with malicious code, tarnishing its reputation.
  • Legal Risks: As mentioned, unauthorized mining could lead to legal consequences.

How does Coinhive compare to other cryptocurrency miners?

Compared to traditional mining software that runs on dedicated hardware or PCs, Coinhive was unique in that it operated entirely within a web browser, requiring no installation. This made it easy to deploy but also less efficient, as browser-based mining typically yields lower hash rates than native mining applications.

Other miners, such as XMRig or NiceHash, are installed as standalone programs and offer more control and higher performance. However, they require users to download software and are often used by those who explicitly choose to mine. In contrast, Coinhive could be embedded in any website, which made it more accessible but also more prone to abuse.

What should website owners know about Coinhive today?

Today, website owners should avoid using Coinhive or any similar mining scripts without explicit user consent. Not only is it ethically questionable and potentially illegal, but it also damages trust and can lead to severe reputational harm. Modern browsers and security tools actively block such scripts, making them ineffective and risky.

If you are considering alternative revenue models, focus on transparent and user-friendly options like ethical advertising, subscriptions, or donations. If you are interested in cryptocurrency, explore legitimate ways to integrate it into your business, such as accepting crypto payments or offering token-based incentives, always with clear communication to your users.

Final Thoughts

Coinhive was a controversial experiment that highlighted the potential and pitfalls of browser-based cryptocurrency mining. While it demonstrated an innovative way to monetize web traffic, its widespread misuse without consent led to its downfall and left a lasting negative impression.

As we move further into 2026, the legacy of Coinhive serves as a cautionary tale for developers and website owners about the importance of transparency and user consent. The technology may evolve, but the principles of ethical implementation remain paramount.

For users, staying vigilant about your device's resource usage and using security tools can help protect against cryptojacking attempts. For creators, always prioritize user experience and trust over short-term gains.