
Mem0
Memori
Agentmemory
Supermemory
Tempreon
cognee
TheSecondBrain.dev
Portable, verifiable memory for AI agents — works across ChatGPT, Claude, Gemini and any MCP client

reCAPTCHA
hCaptcha
Cloudflare Turnstile
Akismet
Private Captcha
mosparo
Cap Captcha
ALTCHA is a free CAPTCHA alternative that uses a proof-of-work mechanism to protect your website, and online services from spam.

Which is more popular?
Based on our record, ALTCHA seems to be more popular. It has been mentioned 4 times since March 2021.
Website, pricing, platforms and company facts side by side.
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| Website | chainmemory.ai | altcha.org |
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| Platforms | — | |
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In their own words, as submitted to SaaSHub.


ChainMemory gives your AI agents persistent memory that belongs to YOU — not to a single vendor. Save a memory in ChatGPT, recall it in Claude or Gemini. Available via Chrome extension, MCP server (npm), or REST API. Every memory gets a cryptographic fingerprint and project states are anchored...
ALTCHA uses a proof-of-work mechanism to protect your website, APIs, and online services from spam and unwanted content. Unlike other solutions, ALTCHA is free, open-source and self-hosted, without external services, does not use cookies nor fingerprinting, does not track users, and is fully...
What each product offers, as listed by its team.


An editorial look at what each product does well and who it suits.


Overall verdict
Why this product is good
Recommended for
No analysis of ALTCHA yet.
How often each product is chosen within a category, 0–100% relative to the other.


As answered by people managing ChainMemory and ALTCHA.
ALTCHA's answer:
What makes ALTCHA unique is that it is free, open-source and self-hosted, without external services, does not use cookies nor fingerprinting, does not track users, and is fully compliant with GDPR. Unlike other captcha solutions, ALTCHA does not require users to solve puzzles or captchas and uses a proof-of-work mechanism instead.
ALTCHA's answer:
Here are some key reasons why a person should choose ALTCHA over its competitors:
So in summary, ALTCHA's privacy compliance, open design, accessibility, machine compatibility and modern approach give it clear advantages over competing captcha solutions.
ALTCHA's answer:
JavaScript and Svelte.
ALTCHA's answer:
Our primary audience for ALTCHA Forms includes enterprises, medium and small businesses, non-profits, and individuals who need a reliable, secure, and compliant solution for data collection and management. Whether you're a large corporation dealing with extensive regulatory requirements, a small business looking to protect customer and employee data, a non-profit organization managing sensitive information, or an individual seeking robust data security, ALTCHA Forms provides the tools and features necessary to meet your needs. With a focus on compliance, user-friendly design, and advanced security measures, our platform is tailored to support diverse users in navigating complex regulatory landscapes and ensuring data protection.
Share your experience with using ChainMemory and ALTCHA. For example, how are they different and which one is better?
Recommendations tracked on public social media and blogs since March 2021.


Tracking ChainMemory since Jul 2026.
ALTCHA won on the boring things. It is open source, self-hosted and collects nothing, and it ships official libraries in both Go and PHP, the two languages our two layers already speak. So the same protocol runs twice on every store, by... - Source: dev.to / about 1 month ago
The captcha on orkestr is Altcha. Self-hosted, no third-party JS, no Google, no behavioral tracking. Users don't see a puzzle. There's a single checkbox and a quiet "verifying..." while the browser does some math. About a second, total. - Source: dev.to / 6 months ago
Here's how PoW works for form protection (using the ALTCHA wire format):. - Source: dev.to / 8 months ago
When comparing ChainMemory and ALTCHA, you can also consider the following products.


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Persistent memory from agent trace, not just conversation
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Do you use a captcha to keep out bots? hCaptcha is a drop-in replacement for reCAPTCHA that earns website owners money and helps companies get their data labeled.
Compare hCaptcha to ChainMemory or ALTCHA:

Persistent memory for Claude Code, Codex & coding agents
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Cloudflare's service for any company to replace CAPTCHAs and deliver a better experience to web visitors.
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