An agent can find a tool and understand its documentation, yet still stop at the checkout. It may need a new account, a card or a subscription before it can do one small job. The x402 payment protocol offers another route: a service presents payment requirements over HTTP, and a compatible client can authorize the purchase within its owner's limits.
Four newly reviewed projects on X402blockchains show different uses for that approach. AISkills402, 402registry, 402cron and 402post accept USDC on Base. They sell different things, so choosing between them starts with the task—not the transaction count.
Four x402 projects, four different purchases
AISkills402 sells downloadable instruction files for agents. A file purchase is distinct from paying for a hosted model or buying an ongoing subscription. Its documentation describes free discovery, HTTP purchases and access recovery. See the AISkills402 project profile and official documentation.
402registry checks how a website appears to an HTTP crawler. The output is a report about what the service observed, rather than a promise of search placement. A site owner might use it when content looks fine in a browser but is missing from a machine's response. Open the 402registry profile.
402cron sells scheduled webhook delivery credits. That makes it relevant when a workflow needs to wake up later or run periodically. Paying for delivery does not mean the destination completed the business task. The receiving application still has work to do. Read the 402cron profile.
402post provides paid classified listings that people and agents can read publicly. The purchase creates a listing with its own lifecycle and management access. It is a publishing service, not an exchange or a guarantee that a buyer will respond. Explore the 402post profile.
How a Base x402 payment fits the workflow
A typical purchase starts with a request to the paid resource. The server returns HTTP 402 and machine-readable payment terms. The client checks the network, asset, recipient, amount and validity period before authorizing anything. A successful response should connect the payment to the resource delivered.
Base is the settlement network for these services; x402 is the payment standard used by the application. Neither name alone tells you which wallet types are supported or who covers gas. Read the particular service's current requirements. Our Base x402 payment guide explains that distinction.
For a first integration, choose one task with an obvious success condition. For example, a report should contain the requested site's findings; a downloaded file should match the expected purchase. Keep a spending ceiling and save the response alongside its receipt. A successful transfer proves money moved, but the application response tells you what was bought.
Read the shared activity correctly
These four projects use a shared recipient wallet. Their directory cards label that scope explicitly. Adding the same wallet total four times would exaggerate activity, and transfers may include operator tests or deposits. The reviewed evidence supports a listing; it does not establish four separate customer or revenue totals. Historical coverage may also be incomplete while backfilling continues.
Common questions
Are these four separate payment networks? No. They are separate services using USDC on Base.
Does a directory approval certify a service's security? No. Review the provider's documentation and terms, and test the workflow within a limited budget.
Where should a builder start? Match the purchase to the job. Continue with skills and website audits or scheduled webhooks and listings.
Sources and further reading
x402 protocol documentation, AISkills402, 402registry, 402cron and 402post. Product details were checked on 7 November 2026; use the live payment offer for current terms.
Reference links
AISkills402 project profile
x402blockchains.com/ai-agents-apps/?project=aiskills402.com
official documentation
aiskills402.com/docs
402registry profile
x402blockchains.com/ai-agents-apps/?project=402registry.com
402cron profile
x402blockchains.com/ai-agents-apps/?project=402cron.com
402post profile
x402blockchains.com/ai-agents-apps/?project=402post.com
Base x402 payment guide
Base x402 Payments: How AI Agents Pay for APIs
skills and website audits
AI Agent Skills and Website Audits: Two Uses for x402 Payments
scheduled webhooks and listings
x402 Automation: Webhooks and Listings for AI Agents
x402 protocol documentation
docs.x402.org/introduction
402registry
402registry.com/
402cron
402cron.com/
402post
402post.com/llms.txt