Open Source reCAPTCHA AlternativesTop Anti-Spam Tools and other similar apps like reCAPTCHA

The best open source alternative to reCAPTCHA is Cap Captcha. If that doesn't suit you, our users have ranked more than 25 alternatives to reCAPTCHA and ten of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to reCAPTCHA are Anubis, Procaptcha, ALTCHA and mosparo.

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Alternatives list

  1. Cap Captcha icon

    Cap Captcha

     25 likes

    Lightweight, modern open-source CAPTCHA alternative designed using SHA-256 proof-of-work and JS instrumentation

    Cost / License

    • Free
    • Open Source

    Application type

    Platforms

    • Self-Hosted
    • Docker
    Cap Captcha screenshot 1
     
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    1
  2. Anubis icon

    Anubis

     17 likes

    Applies sha256 proof-of-work challenges to incoming HTTP requests, targeting AI crawlers, bots that ignore robots.txt, and automated scrapers, protecting server resources and preventing unwanted search engine indexing for privacy-focused sites.

    49 Anubis alternatives

    Cost / License

    • Free Personal
    • Open Source (MIT)

    Application types

    Platforms

    • Self-Hosted
    • Go (Programming Language)
    • Docker
    Anubis screenshot 1
     
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    1
  4. Procaptcha icon

    Procaptcha

     14 likes

    Prosopo Procaptcha redefines user verification with a unique approach that emphasizes privacy and security. It's a pioneering solution designed to offer an alternative to conventional CAPTCHA systems that often compromise user privacy.

    Cost / License

    Application type

    Platforms

    • Online
    • Software as a Service (SaaS)
    • Wordpress
    Procaptcha screenshot 1
     
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    1
  5. ALTCHA icon

    ALTCHA

     8 likes

    ALTCHA is a privacy-first solution built to help developers and website owners stop bots, spam, and automated abuse — without making things harder for real users. It replaces traditional CAPTCHA systems with a smarter, quieter approach to verification and threat detection.

    Cost / License

    • Free
    • Open Source (MIT)

    Application type

    Platforms

    • Self-Hosted
    • Software as a Service (SaaS)
    ALTCHA Sentinel - Self-hosted spam protection for websites, apps, and services.
     
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    1
  6. mosparo icon

    mosparo

     5 likes

    mosparo is the modern solution for protecting your online forms from spam. The protection method is quite simple: mosparo blocks spam using rules matching the form’s data. The detection method is comparable to an e-mail spam filter.

    Cost / License

    • Free
    • Open Source (MIT)

    Application type

    Platforms

    • Online
    • Self-Hosted
    • Python
    • JavaScript
    • Drupal
    • Django
    • PHP
    • Mautic
    • Wordpress
    A screenshot from the software mosparo with the empty project list.
     
  7. mCaptcha icon

    mCaptcha

     4 likes

    A no-nonsense CAPTCHA system with seamless UX | Backend component.

    Cost / License

    Application type

    Platforms

    • Online
    • Self-Hosted
    • Software as a Service (SaaS)
    mCaptcha screenshot 1
     
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    1
  9. IconCaptcha icon

    IconCaptcha

     Like

    conCaptcha is a self-hosted captcha which is faster, more user-friendly and more customizable than other captchas - available for PHP and ASP.NET websites. Users no longer have to read any annoying text images, solve difficult math equations or play any puzzle games.

    Cost / License

    • Free
    • Open Source (MIT)

    Platforms

    • Self-Hosted
    IconCaptcha screenshot 1
     
  10. IronWall icon

    IronWall

     1 like

    IronWall is a Proof-of-Work (PoW) rate-limiting protocol designed to protect high-value API endpoints (AI generation, Auth, SMS triggers) from automated abuse.

    Cost / License

    • Freemium
    • Open Source (MIT)

    Application type

    Platforms

    • Online
    • Software as a Service (SaaS)
    IronWall screenshot 1
     
  11. EU Captcha icon

    EU Captcha

     Like

    Multilingual captcha developed by and for EU countries.

    Cost / License

    • Free
    • Open Source

    Platforms

    • Self-Hosted
     
  12. Captcheck icon

    Captcheck

     Like

    Open source reCAPTCHA alternative.

    Cost / License

    • Free
    • Open Source

    Platforms

    • Online
    • Self-Hosted
    Image mode
     
10 of 10 reCAPTCHA alternatives