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captchas.net is a free hosted CAPTCHA service that provides CAPTCHA images and audio files for website forms. Its goal is straightforward: users identify a random string and submit it, helping reduce the risk of automated form submissions by bots. It uses a shared secret key plus a random string: the CAPTCHA server generates the image, while the site backend calculates and verifies the user’s input using the same rules.
The service supports embedding image links into HTML forms, with parameters for the alphabet, character count, width, height, colors, and more. Audio CAPTCHA offers some accessibility support. The documentation lists examples for PHP, ASP, Perl, Python, JSP, and Apex; Ruby and JavaScript/npm examples are provided via external links. It also mentions integrations with Plone, Joomla, and other systems. Its password algorithm is public: concatenate the secret key and random string, take the MD5 hash, and map it to the alphabet, making it easy for developers to implement backend verification themselves.
The basic service is free and can also be used on commercial websites. If you want to remove the “http://captchas.net/” label from the image, the price is 120 EUR (160 USD) per year. Official form integration is also priced at 120 EUR (160 USD). The page also mentions an easy-to-install image generator binary for self-hosted servers, available on request, but it does not disclose licensing, deployment, or operations details.
The advantages are a low barrier to integration, free commercial use, support for both image and audio CAPTCHA, examples in multiple languages, and backup servers via image.captchas.net and image.backup.captchas.net. The page claims that since 2004, the main server has only had a few minutes of downtime and that the primary and backup servers have never been down at the same time. The drawbacks are also clear: this is a traditional text-recognition CAPTCHA, with limited protection against modern OCR, CAPTCHA-solving services, and more sophisticated attacks. There is no visible admin console, risk scoring, behavior analysis, SLA, privacy compliance information, or payment method details, and the documentation feels dated.
It is suitable for personal sites, legacy systems, CMS forms, comment sections, email address protection, and other scenarios that only need a basic CAPTCHA. It is less suitable for high-risk registration, login, payment, or enterprise-grade anti-fraud use cases. The text does not provide information about access from mainland China, so availability cannot be determined; before production use, it is recommended to test connectivity to the image and audio domains. For more modern alternatives, consider comparing Cloudflare Turnstile, hCaptcha, Google reCAPTCHA, as well as China-based options such as GeeTest, Tencent Cloud CAPTCHA, and Alibaba Cloud CAPTCHA.
⚠ This review is compiled from public sources and does not constitute a purchase recommendation. Verify all facts on the vendor's official site. Verify on captchas.net official site.
captchas.net is an Unknown API & Data provider. TG4G tracks its product information, an overall rating of 5.0/10, and a China-accessibility score of China direct-connect friendly. Click "Visit Official Site" to reach captchas.net directly.