Text & audio
Low
Text-based CAPTCHA
Distorted text rendered for humans and trivial for modern OCR.
View guide
Open CAPTCHA knowledge base
Every CAPTCHA has a weak spot.
39 challenge types, documented with context, integration details, and responsible-use guidance.
39Challenge types
25Risk engines
6Open source
$ captcha identify --url example.com
reCAPTCHA v3 score-based / no widget
$ captcha recommend
01 warmed browser profile
02 residential IP + real session
03 token API (paid fallback)
# verify every assumption before scalingThe library
39 CAPTCHA types. One field guide.
Each entry covers a CAPTCHA format, its context, and documented approaches. Use the filters to narrow the list.
39 / 39 entries
Updated Oct 2026
Risk engine
Medium
reCAPTCHA v2
Google's checkbox and image challenge with strong browser signals.
View guide
Risk engine
High
reCAPTCHA v3
Invisible score-based scoring; no widget is shown to the visitor.
View guide
Risk engine
Very High
reCAPTCHA Enterprise
Enterprise risk scoring with account-level signals and custom rules.
View guide
Risk engine
Medium
Cloudflare Turnstile
Privacy-friendly challenge that leans on browser and network reputation.
View guide
Risk engine
Medium
GeeTest
Slide, icon and word challenges backed by adaptive risk analysis.
View guide
Risk engine
High
Arkose Labs
Enforcement challenges designed to make automated solving expensive.
View guide
Risk engine
Medium
Amazon WAF
AWS bot control with proof-of-work and browser integrity checks.
View guide
Risk engine
Very High
DataDome
Device fingerprinting and behavioural scoring with adaptive challenges.
View guide
Risk engine
Below average
MTCaptcha
Lightweight adaptive CAPTCHA with a mostly invisible default mode.
View guide
Risk engine
Medium
Tencent
Tencent's slider and click challenges tied to a Chinese risk ecosystem.
View guide
Risk engine
Medium
hCaptcha
Privacy-focused image labelling with a large challenge pool.
View guide
Risk engine
Medium
Yandex SmartCaptcha
Yandex's adaptive challenge with browser and behavioural signals.
View guide
Risk engine
High
VK Captcha
VK's rotating image grid with aggressive session checks.
View guide
Open source
Low
Cap
Self-hosted proof-of-work CAPTCHA with a tiny JavaScript widget.
View guide
Risk engine
Medium
Yidun
NetEase's slider and click captcha with encrypted telemetry.
View guide
Risk engine
Medium
VAPTCHA
Chinese slider captcha with device and behaviour scoring.
View guide
Risk engine
Medium
Shumei
Risk control platform with slider and click challenges.
View guide
Risk engine
Medium
Aliyun
Alibaba Cloud's slider captcha with risk-based fallbacks.
View guide
Risk engine
Very High
Imperva
Advanced bot management with fingerprinting and occasional challenges.
View guide
Risk engine
Very High
Kasada
Client-side virtualization and telemetry built to resist automation.
View guide
Risk engine
Very High
HUMAN
Enterprise bot defence with proof-of-work and behavioural checks.
View guide
Risk engine
Very High
Akamai
Bot Manager sensors and adaptive challenges at the edge.
View guide
Image puzzle
Medium
Slider CAPTCHA
Drag a piece into place while the page watches the whole gesture.
View guide
Text & audio
Low
BotDetect
Classic self-hosted text CAPTCHA with audio alternatives.
View guide
Text & audio
Low
Amazon CAPTCHA
The familiar distorted-text challenge used across Amazon properties.
View guide
Risk engine
High
Binance
Puzzle slider used on Binance login and registration flows.
View guide
Risk engine
High
TikTok
Rotating image puzzle tied to device and account signals.
View guide
Text & audio
Medium
Audio CAPTCHA
Spoken challenges intended as an accessible alternative.
View guide
Open source
Low
Altcha
Open-source proof-of-work widget with a native server verifier.
View guide
Open source
Low
Friendly Captcha
Privacy-first proof-of-work challenge from a European provider.
View guide
Open source
Medium
ATB CAPTCHA
Commercial CAPTCHA with a self-hostable open-source core.
View guide
Open source
Medium
CaptchaFox
Modern privacy-focused challenge with open-source components.
View guide
Image puzzle
Below average
Capy Puzzle
Small puzzle slider that is friendly to scripted solving.
View guide
Image puzzle
Medium
CutCaptcha
Slider puzzle with server-side verification and lightweight assets.
View guide
Image puzzle
Medium
Lemin
Image-based puzzle captcha with several challenge layouts.
View guide
Open source
Medium
Prosopo Procaptcha
Open-source proof-of-humanity protocol with a hosted option.
View guide
Risk engine
High
Temu
Rotating image and slider challenge used on Temu flows.
View guide
Risk engine
Medium
ARCaptcha
Hosted CAPTCHA widget with interactive and invisible modes.
View guide
No matches.
Try a different name or reset the filters.
A practical field guide
Understand the challenge. Choose responsibly.
Start with context and evidence, then compare documented options with their trade-offs and limits.
Recognize what you’re seeing
Browse concise profiles of CAPTCHA types, their common formats and the signals that distinguish them.
Review the available paths
Explore documented open-source projects and service options, with practical trade-offs called out.
Keep permission in scope
Use this reference for learning and authorized testing; respect privacy, site rules and applicable law.
Challenge difficulty
Low
Below average
Medium
High
Very high
Operating principles
Free first. Evidence over guesses.
The guide is built around repeatable research, not a single magic solver or a pile of affiliate links.
Start with open tools
Every page begins with open-source libraries and practical browser methods before it mentions a paid service.
Read the signals
Network requests, cookies and injected scripts reveal more than the screenshot. Identify the vendor before writing code.
Respect the target
Use this material for education and authorised testing. Honour terms of service, rate limits and privacy.
Help keep the guide useful.
Found a missing reference or an outdated detail? Contributions help make this knowledge base clearer and more responsible.