secure-checkout

secure-checkout is a skill for Claude Code, Codex from finsilabs/awesome-ecommerce-skills. It costs 28 tokens per session (3,457 once invoked), scanned A, original, MIT.

A guide to protecting an online payment page from attacks such as script injection and card-data theft.

In plain words
What is it for?
Use it when building or reviewing checkout pages, configuring HTTPS and security headers, controlling third-party scripts, and preparing for PCI DSS assessments.
Why use it?
It helps reduce weaknesses in checkout security and limits how much card-payment security work your own systems must handle.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions Codex; mentions Gemini CLI; mentions OpenCode.

Good fit Use it when building or reviewing checkout pages, configuring HTTPS and security headers, controlling third-party scripts, and preparing for PCI DSS assessments.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/finsilabs/awesome-ecommerce-skills/secure-checkout
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add finsilabs/awesome-ecommerce-skills --skill secure-checkout
Clone the repo
git clone --depth 1 https://github.com/finsilabs/awesome-ecommerce-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for secure-checkout

README.md
[![agentmods](https://agentmods.dev/badge/skills/finsilabs/awesome-ecommerce-skills/secure-checkout/github.svg)](https://agentmods.dev/skills/finsilabs/awesome-ecommerce-skills/secure-checkout)
Your own site
<a href="https://agentmods.dev/skills/finsilabs/awesome-ecommerce-skills/secure-checkout"><img src="https://agentmods.dev/badge/skills/finsilabs/awesome-ecommerce-skills/secure-checkout/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for secure-checkout

Your own site · 80×15
<a href="https://agentmods.dev/skills/finsilabs/awesome-ecommerce-skills/secure-checkout"><img src="https://agentmods.dev/badge/skills/finsilabs/awesome-ecommerce-skills/secure-checkout.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 28 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,457 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00028 $0.03457
Opus 5 $0.00014 $0.01729
Sonnet 5 $0.00006 $0.00691
Haiku 4.5 $0.00003 $0.00346

Measured 9d ago against content hash d4097a9467a2, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

secure-checkout scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/security-compliance/secure-checkout/SKILL.md · 284 lines

How it starts

The opening of the file, as written. The whole thing — 284 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Secure Checkout

Overview

Payment pages are the highest-value target for attackers — a single XSS vulnerability can lead to Magecart-style card skimming attacks that steal thousands of card numbers. Securing checkout requires enforcing TLS everywhere, implementing strict Content Security Policies (CSP) to prevent script injection, using payment tokenization to minimize PCI scope, and removing non-essential third-party scripts from payment pages. The good news: Shopify and BigCommerce handle most of this infrastructure automatically. WooCommerce merchants need to configure hosting and install security plugins. Custom storefronts require implementing all of these controls from scratch.

When to Use This Skill

  • When building or auditing a checkout flow that accepts payment information
  • When a penetration test or security scan surfaces XSS, CSP, or header vulnerabilities on payment pages
  • When reviewing third-party script loading on pages that have access to payment form context
  • When preparing for PCI DSS SAQ A-EP or SAQ D compliance assessment
  • When migrating from a hosted payment page to a custom UI (increases PCI scope)

Core Instructions

Step 1: Understand your checkout security responsibility by platform

Platform HTTPS / TLS CSP Headers Payment Tokenization Third-Party Script Control
Shopify Automatic — Shopify provisions and renews SSL certificates Shopify manages checkout CSP; your theme pages need review Shopify Payments and all gateway integrations use tokenization Use Shopify's Script Manager and Customer Events to control what loads on checkout
WooCommerce Your hosting responsibility — install SSL from Let's Encrypt or your host Your server responsibility — configure via hosting or plugin Determined by your gateway choice (Stripe Elements = SAQ A-EP) WordPress plugin and theme scripts load globally; use conditional loading to exclude checkout
BigCommerce Automatic — BigCommerce provisions SSL and enforces HTTPS BigCommerce manages checkout CSP for hosted checkout Handled by your payment gateway choice through BigCommerce checkout BigCommerce Script Manager controls third-party script placement
Custom / Headless Your infrastructure responsibility Your application responsibility — implement per-request CSP with nonces Implement with Stripe Elements or Braintree Drop-in UI Full control and full responsibility — must implement explicitly

Read the full file on GitHub · 284 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 9d ago First seen · 284 lines · 28 tokens per session scan A d4097a9467a2

Subscribe to this mod's changes

secure-checkout is a skill published in the GitHub repository finsilabs/awesome-ecommerce-skills (52 stars, last pushed 6mo ago), licensed MIT. It adds 28 tokens to every session and 3,457 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.