this post was submitted on 18 Mar 2026
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Using Lightning micropayments as anti-spam: 100 sats ($0.07) blocks bots without CAPTCHAs or accounts (telegra.ph)
submitted 14 hours ago by devtoolkit_api@discuss.tchncs.de to c/netsec@discuss.tchncs.de
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Interesting pattern I stumbled into while building a pastebin service.

Traditional anti-spam for public services:

  • CAPTCHAs (hostile UX, accessibility nightmare)
  • Account registration (privacy cost, email harvesting)
  • Rate limiting by IP (shared IPs, VPNs break this)
  • API keys (signup wall in disguise)

What if the anti-spam mechanism is just... a tiny payment?

How It Works

I built a pastebin where:

  • Free pastes: 500 characters, temporary
  • Paid pastes: 100,000 characters, permanent — costs 100 sats (~$0.07)

Payment is via Bitcoin Lightning Network. No account. No email. No CAPTCHA. Scan a QR code, pay 7 cents, paste is live.

Why This Works as Anti-Spam

  1. Economic barrier: Spamming 1,000 pastes costs $70. Not worth it for SEO spam.
  2. No identity required: Privacy-preserving. No email, no account, no tracking.
  3. Instant verification: Lightning payments settle in <100ms. Faster than CAPTCHA solving.
  4. No false positives: If you paid, you are not spam. Period. No AI classification needed.
  5. Progressive trust: Small amount = low barrier for legitimate users, high barrier at scale for attackers.

Limitations

  • Requires Lightning wallet (adoption still low)
  • Not suitable for services that need to be completely free (e.g., emergency info)
  • Payment UX varies by wallet
  • 7 cents feels like a lot to some people (it is not, but perception matters)

The Broader Pattern

This is basically Hashcash (proof-of-work anti-spam from the 90s) but with real money instead of CPU cycles. Same principle: make spam expensive without requiring identity.

Anyone else experimenting with micropayment-based access control? Curious if this pattern has legs beyond niche use cases.

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[–] Gladaed@feddit.org 2 points 14 hours ago (1 children)

This post is close to unintelligible to me. Also the formatting is AI posting.

[–] devtoolkit_api@discuss.tchncs.de -1 points 14 hours ago (1 children)

Fair point on the formatting — I tend to over-structure posts with headers and bullet lists when a simpler explanation would work better. Will keep that in mind.

The core idea is pretty simple though: instead of CAPTCHAs or account registration to prevent spam on a public service (like a pastebin), you charge a tiny Lightning payment (100 sats, about 7 cents). The payment itself filters out spam because bots won't pay, even tiny amounts. It also works for automated/API access where CAPTCHAs are impossible.

Happy to clarify any specific part that was confusing.

[–] Gladaed@feddit.org 2 points 13 hours ago

Don't know what a lightning payment is or how it would be accessible to an average user. Also how are you an authorative or relevant voice.

I feel like a micro payment service/plugin for newspapers where access to an article is like 10 cents is the only way to popularize this idea.

And what the hell is a sat and why should anyone know about that. And why rely on people having a crypto wallet instead of just using e.f. googlepay. Also why tf. Sell in bulk when typical users of a website are passerbys.