Terms of Service

You agree to use the service in a lawful manner. The following are prohibited:

• Abusing, overloading, or attempting to degrade the service infrastructure
• Reverse engineering or attempting to bypass the verification system
• Using the service for illegal activities or to intentionally harm others
• Reselling or sublicensing access to the API without prior written consent
• Using the Free tier for commercial purposes. The Free tier is strictly limited to personal projects, open-source work, and non-commercial testing. Commercial use requires a paid plan. In the event of a breach of this condition, I reserve the right to suspend or terminate the account without prior notice.

Usage limits depend on your selected plan. Limits are applied per account (not per project) and are based on the number of challenge requests generated by the service. The following limits apply per billing period:

The Free tier does not include email support. Free tier users have access to documentation only. Email support is available exclusively on paid plans.

Each plan also limits the number of projects you may create. Project limits are hard limits — new projects cannot be created once the limit is reached.

Request limits are applied per account (not per project) and are based on the number of challenge requests generated. Challenge requests are counted when a challenge is generated via the API, regardless of whether it is subsequently verified.

When the monthly request limit is exceeded, challenges are not blocked. Requests continue to be served, but at the easiest possible PoW difficulty, effectively providing no meaningful protection against automated abuse. This design ensures your end-users are never impacted by your account's usage state. You will be notified by email when you approach and exceed your limit.

Persistent over-limit usage across multiple billing periods may result in escalating action. Accounts exceeding their limit for a second consecutive month will receive a follow-up notification. Accounts exceeding their limit for a third consecutive month are subject to manual review, which may result in account suspension if no upgrade or corrective action is taken.

In addition to request limits, your plan determines the baseline PoW difficulty applied to challenges issued from your projects. Free plan challenges require approximately 4,096–65,536 hash iterations per visitor. Starter plan challenges require approximately 2,048–32,768 iterations (2× easier), Growth plan approximately 1,365–21,845 iterations (3× easier), and Pro plan approximately 1,024–16,384 iterations (4× easier). Actual difficulty scales smoothly with per-IP traffic volume.

Upgrading to a paid plan requires providing a valid billing address. Business customers (entrepreneurs) must additionally provide a company registration number and VAT number where applicable, as required for invoicing under Czech and EU law. This information is retained for the period required by applicable accounting legislation (10 years from the date of the last invoice) regardless of account deletion.

Paid plans are billed on a monthly subscription basis. Payments are processed by Lemon Squeezy acting as Merchant of Record. By subscribing, you authorize recurring charges at the rate associated with your chosen plan.

If a payment fails, your account is not immediately suspended and does not revert to the Free tier. Instead, a grace period of 14 days begins during which your account continues to function normally. You will receive daily reminder emails with instructions on how to resolve the payment issue.

Accounts on a paid plan that fail to pay are not transferred to the Free tier, as the Free tier permits only non-commercial use. A suspended account is a separate state that preserves your configuration and data until the payment issue is resolved.

When you integrate captchaapi.eu into your website or application, captchaapi.eu acts as a data processor on your behalf for the purpose of providing the CAPTCHA service to your end users. You remain the data controller responsible for that processing.

By accepting these Terms, you enter into a Data Processing Agreement (DPA) with captchaapi.eu in accordance with Article 28 GDPR. Under this agreement captchaapi.eu commits to:

• Process personal data only on your documented instructions (i.e. providing the CAPTCHA service)
• Ensure that authorized personnel are bound by confidentiality
• Implement appropriate technical and organizational security measures (Art. 32 GDPR)
• Engage sub-processors only with your general authorization (sub-processors are listed in the GDPR Policy)
• Assist you in fulfilling your obligations regarding data subject rights and security incidents
• Delete or return all personal data upon termination of the service relationship, except where retention is required by applicable law

The subject-matter, nature, purpose, and duration of processing are described in the Privacy Policy and GDPR Policy.