Frequently Asked Questions

ALTCHA is a CAPTCHA alternative that verifies visitors with a silent proof-of-work challenge instead of puzzles or image quizzes — no tracking, no cookies, and nothing for real users to solve. See How ALTCHA Works for a full walkthrough.

Yes — the open-source widget is free forever, with no sign-up, API keys, or usage limits. Paid Cloud and Sentinel plans add hosted analytics and adaptive threat protection for teams that need it.

Yes — the open-source widget requires no sign-up, API keys, or account. Cloud and Sentinel both offer a 30-day free trial, no credit card required.

Yes. ALTCHA sets no cookies, does no fingerprinting, and shares no data with third parties, so there's nothing that requires consent. See our GDPR compliance page for details.

Yes. ALTCHA is WCAG 2.2 AA conformant, fully keyboard-navigable, and screen-reader labelled, with no visual puzzles to solve.

No, by default — the widget submits its verification payload as a hidden form field, not a cookie. It can optionally be configured to use a cookie instead if your integration needs it, but nothing is used for tracking either way.

Yes. ALTCHA's no-cookies, no-tracking design means it doesn't collect the kind of personal data that GDPR, CCPA, and similar regulations require consent for — across the open-source core, Cloud, and Sentinel.

Cloud is fully managed by us on EU servers — no setup or maintenance — with adaptive CAPTCHA, threat intelligence, and analytics built in. Sentinel runs the full platform on your own infrastructure, adding features like the Classifier, for teams with strict data-residency or on-premise requirements.

Yes — both come with a 30-day free trial, no credit card required. You can also stay on the free open-source widget indefinitely.

Yes. The WordPress plugin includes a free plan covering essential protection for login, registration, and comments — no sign-up required. A paid Professional plan adds coverage for 22+ additional form plugins, extra sites, and priority support.

Yes — you can move between the open-source core, Cloud, and Sentinel without changing your widget integration, and upgrade or downgrade Cloud or Sentinel plans at any time, with the price difference prorated.

Most teams switch in under an hour — the widget is a drop-in replacement, and your existing form-submission flow stays the same. Step-by-step guides are available for reCAPTCHA, hCaptcha, and Cloudflare Turnstile.

Official libraries and plugins cover every major frontend framework (React, Vue, Svelte, Solid, Lit, Angular) and backend language (JS/TS, Python, PHP, Go, Java, Ruby, Rust, C++, Dart, Elixir), plus WordPress and mobile SDKs for Flutter and React Native.

No — the widget requires JavaScript and a secure HTTPS connection, since it relies on the browser's built-in SubtleCrypto API to compute its challenge. Local development works fine over http://localhost, which browsers also treat as a secure context.

Not necessarily. With Cloud or Sentinel, you can point the widget directly at your challenge endpoint with no backend code required. Using just the open-source core, you'll need a small server-side integration to generate challenges and verify submissions — see Quick Start.

Docker, Docker Compose, Kubernetes, AWS ECS, Azure App Services, and Bunny.net — all configured the same way, by setting environment variables on the container. See Install for platform-specific guides.

Yes. By default, Sentinel periodically verifies its license with a minimal, non-telemetry call to eu.altcha.org (application version, node ID, and process ID only). For air-gapped deployments, set LICENSE_JSON instead of LICENSE_KEY to the license file from your purchase confirmation email, and it verifies entirely offline. See License.

Sentinel ships with an embedded, zero-config SQLite backend for evaluation or single-instance use. Professional and Enterprise plans can point it at PostgreSQL, MySQL, MariaDB, or LibSQL instead; Enterprise also adds Microsoft SQL Server and Oracle. See Databases.

Yes. Clustering is supported once you add a shared KV store — Redis, Valkey, or the S3-backed Turbolite option — with instance-count limits tied to your license tier. See Clustering.

Yes, on the Enterprise license. See SSO.