Guides for engineers building AI agents
Long-form documentation on the x402 protocol, AI agent payments, residential proxies, stealth browsers, SMS verification, and the operational infrastructure agents need. Each guide is written to stand alone — extractable by AI search engines, citable by name.
- Explainer2026-04-15
What is x402? The HTTP 402 payment protocol explained
x402 is an open standard that revives the HTTP 402 status code for machine-to-machine micropayments. A server replies 402 with a JSON manifest describing the payment terms (asset, network, payTo, amount). The client s…
- Tutorial2026-04-22
How AI agents pay for resources with x402 — a working example
An AI agent that needs an SMS OTP number sends a normal HTTP request to /v1/sms/otp. The server replies 402 with an x402 manifest specifying $0.10 in USDC on Base, payTo, and a quote. The agent's wallet signs the tran…
- Comparison2026-04-26
x402 vs Skyfire vs Crossmint vs AgentKit — agent payment options compared
x402 is an HTTP-level protocol — fifty lines of server code, no SDK on the agent side. Skyfire is a payment network with KYC and per-trip authorisations. Crossmint is a Web3 commerce SDK with cards plus stablecoins. C…
- Deep dive2026-04-28
AI agent SMS verification — how it works and why agents need it
Most consumer-facing sites require an SMS OTP during signup. Autonomous agents cannot register a Twilio account, so they buy disposable inbound numbers from agent-native vendors. Agent402 Stock provides US/EU numbers …
- Deep dive2026-04-29
Residential proxies for AI agents — pay-per-use, no monthly minimum
Residential proxies are exit IPs assigned to real consumer ISPs, not datacenters. Most consumer-facing websites and login flows now block datacenter ranges. AI agents that need to interact with these sites buy residen…
- Deep dive2026-04-30
Stealth browser for AI agents — fingerprint-clean Chromium on demand
AI agents that need to interact with anti-bot-protected sites (Cloudflare, DataDome, Akamai) cannot use vanilla Chromium — its default fingerprint is detected on day one. Stealth browsers ship with randomised canvas, …