Alternatives to Cap

CAPTCHA	Open-source	Free	Private	Fast to solve	Easy for humans	Small error rate	Checkpoints	Widget support	GDPR/CCPA Compliant	Customizable	Hard for bots	Easy to integrate
Cap	✅	✅	✅	✅	✅	✅	✅	✅	✅	✅	✅	✅
Cloudflare Turnstile	❌	✅	🟨	🟨	✅	❌	🟨	✅	✅	❌	🟨	✅
reCAPTCHA	❌	🟨	❌	✅	❌	🟨	❌	✅	🟨	❌	❌	✅
hCAPTCHA	❌	🟨	🟨	❌	❌	🟨	❌	✅	🟨	❌	🟨	✅
Altcha	✅	✅	✅	✅	✅	✅	❌	✅	✅	✅	🟨	🟨
FriendlyCaptcha	❌	❌	✅	🟨	✅	✅	❌	✅	✅	✅	🟨	🟨
MTCaptcha	❌	🟨	🟨	❌	❌	🟨	❌	✅	✅	❌	❌	🟨
GeeTest	❌	❌	❌	🟨	🟨	🟨	❌	✅	✅	❌	🟨	🟨
Arkose Labs	❌	❌	❌	❌	❌	❌	❌	❌	✅	🟨	❌	🟨

Note

"Hard for bots" for Cap refers to the combination of Proof-of-Work and dynamic instrumentation challenges. It does not consider commercial solvers like BrightData, as I cannot verify their legitimacy myself.

All alternatives

Cloudflare Turnstile

Cloudflare Turnstile is a great alternative to Cap, but unfortunately, it is known for having an extremely high error rate and relies a lot on fingerprinting, especially for users using private browsers such as Brave or Librewolf.

Additionally, unlike Turnstile, Cap is open-source and self-hosted. With Turnstile, if Cloudflare's algorithm marks a user as "suspicious," you cannot override it. Cap puts the levers of control in your hands, so you decide the difficulty and strictness, not a third party.

reCAPTCHA

Not only is Cap significantly smaller and faster than reCAPTCHA, it's open-source, fully free, and much more private. Cap doesn't require you to check traffic signs or solve puzzles, and it doesn't track users or collect data.

reCAPTCHA v2 ("I'm not a robot") is getting harder for humans while remaining trivial for AI solvers (especially audio challenges). v3 (Invisible) is great, but if Google thinks you are "suspicious" (e.g., using a VPN or privacy tools), it often blocks you entirely or forces a hard puzzle loop with no way out.

hCAPTCHA

Pretty much the same as reCAPTCHA, however, while it's significantly more resistant to bots, it imposes a heavy "Puzzle Tax" on your users.

Users hate puzzles. They leave. Drop-off rates on hCaptcha challenges can be 5-15% depending on difficulty. Additionally, hCaptcha's free tier is aggressive with serving puzzles to save their own costs, which hurts your conversion rates.

Altcha

Cap is slightly smaller than Altcha and includes extra features like progress tracking, instrumentation challenges, and a simpler dashboard. If you don't need these, Altcha is still a solid choice.

mCAPTCHA

While mCAPTCHA is similar to both Cap and Altcha, it seems to have been deprecated and has a significantly larger widget bundle.

FriendlyCaptcha

Unlike FriendlyCaptcha, Cap is completely free and self-hosted (FriendlyCaptcha is €39/month for only 5k requests and 5 domains).

MTCaptcha

MTCaptcha relies heavily on image challenges, which are usually easily solvable by LLMs and OCRs and have high drop-off rates. Cap is also lightweight, self-hostable and doesn't rely on obfuscation.

GeeTest

Cap is free, self-hosted, and open-source, while GeeTest is a paid service. Cap is also more private and doesn't rely on tracking users or collecting data. GeeTest is also China-based, which may be a concern for some users regarding data sovereignty.

Arkose Labs

Arkose's CAPTCHA is known for being hard, slow, and annoying for humans to solve. It is also a paid, closed-source service mostly available to big enterprises.

Anubis

While Anubis is a great scraper deterrent and uses the same proof-of-work concept as Cap, it uses a low difficulty by default (which is easier for bots to solve) and does not provide a standalone CAPTCHA server.

Cap also implements dynamic instrumentation challenges, which make it harder for bots to finish the process after solving PoW.