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X402

Category: Engineering  ·  Sub-category: engineering-misc  ·  Last updated:
lang:pythonlang:typescript
Build internet-native payments with the x402 open protocol (x402 Foundation, Apache-2.0). Use when developing paid APIs, paywalled content, AI agent payment flows, or any service using HTTP 402 Payment Required for on-chain micropayments. Covers TypeScript (2.9.0), Python (2.6.0), and Go (2.7.0) SDKs across EVM (Base, MegaETH, Monad, Polygon, Stable, Arbitrum), Solana, Stellar, and Aptos networks with HTTP, MCP, and A2A transports. Supports exact and upto (usage-based) payment schemes, self-facilitation, and extensions (bazaar, gas sponsoring, sign-in-with-x).
Security AStatic scan found no risk patternsHow grading works ›

From the source SKILL.md

x402 is an open standard (Apache-2.0) that activates the HTTP 402 Payment Required status code for programmatic, on-chain payments. Originally created by Coinbase, now maintained by the [x402 Foundation](https://github.com/x402-foundation/x402). No accounts, sessions, or API keys required - clients pay with signed crypto transactions directly over HTTP.

What this skill does

X402 is a community-contributed Claude Code skill in the engineering-misc sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/x402/ and loads when your prompt matches the skill's trigger.

When to invoke it: Use when developing paid APIs, paywalled content, AI agent payment flows, or any service using HTTP 402 Payment Required for on-chain micropayments. Covers TypeScript (2.

Who uses this skill

The X402 Claude Code skill is built for software engineers, backend developers, full-stack teams, and technical leads building and maintaining production systems. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 211,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).

How to install

Free

Manual install (2 steps)

mkdir -p ~/.claude/skills/x402
curl -L https://claudskills.com/skills/x402/SKILL.md \
  -o ~/.claude/skills/x402/SKILL.md

Or just download SKILL.md directly and drop it into ~/.claude/skills/x402/. Claude Code auto-discovers it on next session.

Skills live at ~/.claude/skills/x402/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\x402\SKILL.md on Windows. See the full install guide for step-by-step instructions.

Telegram

📱 Install from your phone or desktop Telegram

Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →

Pro

One-click install via the desktop app

The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.

Pro

For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.

See pricing → Download desktop app

Frequently asked questions

How do I install the X402 Claude Code skill?
Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/x402/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.
What does the X402 skill do?
Build internet-native payments with the x402 open protocol (x402 Foundation, Apache-2.0). Use when developing paid APIs, paywalled content, AI agent payment flows, or any service using HTTP 402 Payment Required for on-chain micropayments. Covers TypeScript (2.9.0), Python (2.6.0), and Go (2.7.0) SDKs across EVM (Base, MegaETH, Monad, Polygon, Stable, Arbitrum), Solana, Stellar, and Aptos networks with HTTP, MCP, and A2A transports. Supports exact and upto (usage-based) payment schemes, self-facilitation, and extensions (bazaar, gas sponsoring, sign-in-with-x).
Is this skill free to install?
Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.
When should I use the X402 skill?
Use X402 when your Claude Code task falls under the Engineering category — specifically in the engineering misc area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use X402" or describe the task and let Claude pick). Browse related skills at /category/engineering/.
What is a Claude Code skill and how does the X402 skill fit in?
A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. X402 is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Engineering category. Learn more at /learn/what-is-a-claude-skill/.

Attribution & license

Cite this skill

If you reference this skill in a blog post, paper, or documentation, you can cite it as:

APA
x402-foundation. (2026). X402 [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/x402/
BibTeX
@misc{x402-2026,
  author    = {x402-foundation},
  title     = {X402 [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/x402/}
}

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Security scan

Grade A · scanned 2026-10-25 — free static scan against the OWASP Agentic Skills Top 10.

The scan flagged 1 of 10 categories (supply-chain), including lower-severity patterns. Patterns shown inside code fences are weighted as examples rather than instructions — read the grading methodology for what this does and does not guarantee.

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Browse all Engineering skills in the ClaudSkills registry, or explore these other picks from the same category:

Browse all Engineering skills → Top 100 skills
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