#10 in Application SecurityUpdated 2026-08

ALTCHA

by ALTCHA · Self-hosted, privacy-first captcha and bot protection

62.6 — BenchRank score out of 100

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Overview

ALTCHA is a captcha and bot-protection system with an MIT-licensed open-source core that works without cookies, tracking or external calls. The widget defaults to proof-of-work verification and escalates to a code challenge with audio for high-risk cases. ALTCHA Sentinel adds self-hosted threat intelligence, rate limiting and text classification; ALTCHA Cloud is the EU-hosted version.

Best for: Teams needing a self-hosted, GDPR- and WCAG-compliant captcha to replace reCAPTCHA on sites and forms.
Pricing: The open-source widget is free and ALTCHA Cloud costs €47, €137 or €187 per month excluding VAT with a 30-day trial, while self-hosted Sentinel prices are not shown.
Runs on: Self-hosted

Strengths and trade-offs

Strengths

MIT-licensed core; no cookies, tracking or external calls
34 kB widget vs 85 kB+ Turnstile and 300 kB+ reCAPTCHA
WCAG 2.2 AA with audio code challenge; 50+ languages incl. RTL
Server libraries for 10 languages, plus Flutter and React Native

Trade-offs

Cloud omits full Sentinel features like custom rules and data classification
Cloud is capped at 1,000 API requests/day; 10,000 on Plus, 20,000 on Max
Self-hosting Sentinel needs your own infrastructure and a supported SQL database
No published price for self-hosted Sentinel beyond the 30-day trial

Pricing

Published plans from ALTCHA’s own pricing page, in EUR. Usage charges and add-ons may apply on top.

ALTCHA pricing tiers, monthly rates in EUR
Plan	Monthly	Includes
Cloud	€47per account	Up to 3 sites per account Fair-use API: 1,000 requests/day, bursts of 100/hour EU-only endpoints and email support 30-day free trial
Cloud Plus	€137per account	Up to 10 sites per account 10x Cloud API capacity: 10,000 requests/day Same protection and compliance as Cloud 30-day free trial
Cloud Max	€187per account	Up to 50 sites per account 20x Cloud API capacity: 20,000 requests/day Same protection and compliance as Cloud 30-day free trial

How this score is made up

Each dimension is scored out of 100 and combined into the headline score using fixed weights.

MCP support: 0 out of 100
API quality: 50 out of 100
Documentation: 80 out of 100
Agent friendliness: 83 out of 100
Pricing transparency: 85 out of 100
Changelog: 100 out of 100
Marketing site structure: 75 out of 100
Operational trust: 85 out of 100

Measured, but not part of the score

Useful to know, but not a mark for or against the product — so these do not affect the ranking.

Openness: 100 out of 100
Maintenance: 100 out of 100

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