Sign in Submit site

mCaptcha

mcaptcha.org Security Tools Website

Add proof-of-work verification to websites with mCaptcha, a privacy-focused automated CAPTCHA system.

Visit mCaptcha 24 alternatives
mcaptcha.org
mCaptcha homepage screenshot

About mCaptcha

mCaptcha is a proof-of-work based CAPTCHA system for websites. Instead of asking visitors to pick out images or solve puzzles, it issues a small computational task that the browser completes in the background. The project describes this check as silent, meaning visitors generally do not notice it.

It is aimed at site owners who want to block automated abuse without collecting personal data. According to the homepage, mCaptcha does not track or profile users and does not use IP addresses for rate limiting, so visitors behind NAT or shared addresses are treated the same as anyone else. Its APIs are compatible with reCAPTCHA and hCaptcha, so an existing integration can be swapped out.

The core is licensed under the AGPL and client libraries use free software licenses, according to the site. Setup is aimed at developers who can add a client library to their site and configure the service, with "Try mCaptcha" and "Get started" entry points offered on the homepage.

Key features

  • Proof-of-work captcha that runs silently with no image puzzles
  • Does not track or profile site visitors
  • Rate limiting does not use IP addresses, so NAT users are unaffected
  • APIs compatible with reCAPTCHA and hCaptcha for drop-in replacement
  • Core licensed under AGPL; client libraries use free software licenses
Best for: Site owners and developers who want to block automated abuse without image challenges or user tracking.
Good for
  • Privacy-focused: does not track or profile visitors
  • Silent check, with no images or puzzles for users to solve
  • Works for visitors behind NAT because IP addresses are not used for rate limiting
  • Compatible APIs make it a drop-in replacement for reCAPTCHA and hCaptcha
Watch out for
  • Pricing is not stated on the homepage
  • Visitors' browsers must perform a computational task

mCaptcha at a glance

Type
Website
Pricing
Not confirmed. Check the site
Platforms
Web
Open source
Not stated
Language
English
Last checked
Oct 5, 2026 · Online when checked
Listed
Oct 5, 2026
securitysecurity toolscaptcha

mCaptcha alternatives

Tools and sites you could use instead, ranked by how closely they match.

All 24 alternatives

Popular in Security Tools

Well-known listings from the same topic.

All 202
Online Password Hash Crackonlinehashcrack.comOTP Authapps.apple.com/app/otp-auth/id659877384MD5 reverse lookupmd5.gromweb.comMozilla SSLssl-config.mozilla.orgGoPlus Locker V3gopluslabs.ioSuperagentsuperagent.sh
Related topicsVPNsPrivate EmailWebsite & URL ScannersDesktop & OS PrivacyAd & Tracker BlockersSecurity ResearchPrivacy GuidesPassword Managers

mCaptcha FAQ

What is mCaptcha?
mCaptcha is a proof-of-work based CAPTCHA system for websites. It is described as privacy focused and fully automated, and it verifies visitors by having their browser perform a small computational task.
Does mCaptcha track or profile users?
The homepage states that mCaptcha does not track and does not profile users. It also says IP addresses are not used for rate limiting, so visitors behind NAT are handled the same way as others.
Can mCaptcha replace reCAPTCHA or hCaptcha?
According to the homepage, mCaptcha's APIs are compatible with reCAPTCHA and hCaptcha, so it can be used as a drop-in replacement for an existing captcha solution.
Is mCaptcha free software?
The homepage says the core is licensed under the AGPL, while client libraries use proprietary-friendly free software licenses. It states that mCaptcha will always be free.
Is something wrong or out of date?

Tell us and an editor will check it.

Own this website?

Claim the listing and suggest updates yourself. An editor checks every claim first.

Claim this listing

Listing maintained by Chris McClure and the WebIndexly editors · Updated Oct 6, 2026 · How we rank