21.cash

What it does

Create and share payment links with automatic revenue splitting on Base via x402 protocol sell alpha, gate an api endpoint, split payments across addresses or simply invoice clients globally, settles instantly on chain.

Wrap any API or URL in an x402 paywall, get listed where agents discover services, and settle in USDC on Base. No API keys, no invoices, no subscription.

• 
  USDC to Bank2023 · pipes.tech · ▲113

  Go from crypto to fiat in your bank, in minutes

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  x4022025 · x402.org · ▲119

  Hi HN – excited to announce x402, initially developed by Coinbase (YC 12) x402 lets any HTTP API charge per request without issuing API keys or storing credit cards. Buyers (humans or AI agents) keep funds in their own wallet and dynamically discover compatible endpoints, call them as usual, and automatically pay a microtransaction in USDC or other tokens to settle. 90 second demo: https://www.youtube.com/watch?v=PV-L2AfLhJg Problem: Every time we want to use a new API we have to: find the service online create a developer account, copy a secret key into env vars, pre-fund or…

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  Pay With USDC2022 · paywithusdc.xyz · ▲90

  A safe way for businesses to send crypto

• 
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• 
  Wordpress Crypto Plugin2022 · wordpress.org · ▲80

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• 
  Triple Payments2022 · ▲84

  Request crypto from anyone by sharing a link

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  I spent 3 years reverse-engineering a 40 yo stock market sim from 1986▲721

  Hello my name is Ben Ward for the past 3 years I have been remastering the financial game Wall Street Raider created by Michael Jenkins originally on DOS in 1986. It has been a rough journey but I finally see the light at the end of the tunnel. I just recently redid the website and thought maybe the full story of how this project came to be would interest you all. Thank you for reading.

  Work · Feb 2026 · wallstreetraider.com