We’ve added ALTCHA solver support — you can now solve it via our API. Send the site data, receive the answer, and automate workflows on target sites.

ALTCHA — Key Technical Features

1. Proof-of-Work (PoW) instead of visual puzzles
ALTCHA replaces image- or interaction-based challenges with a lightweight PoW task. The server sends a JSON payload describing the challenge; the browser computes a nonce that satisfies the PoW condition. This is a simple cryptographic proof that helps distinguish human-driven requests from bots.

2. Stateless verification
ALTCHA does not rely on cookies, fingerprinting, or tracking. Verification is based solely on the computed nonce, which the server can validate independently of client state.

3. Asynchronous browser execution
Nonce computation runs in the background (for example, in a Web Worker) so the UI remains responsive. Once a valid nonce is found, the browser submits the token to the server for verification.

4. Server-side validation
The server verifies that the submitted nonce meets the required difficulty and corresponds to the originally issued challenge. If validation succeeds, the request is treated as human-initiated.

5. Flexible integrations
ALTCHA can be deployed on your own servers. You can tune PoW difficulty, add custom checks, and integrate the challenge into forms or API endpoints as needed.

6. Simple protocol
All interactions are exchanged as JSON, making the protocol straightforward to implement and extend.

How to solve ALTCHA

Submit a task to a solver service via the API.

Summary

Solving ALTCHA requires a solver service. See the documentation for details: API for solving ALTCHA

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