twelve-factor-app

twelve-factor-app is a skill for Claude Code from Vimalk0703/shipworthy. It costs 44 tokens per session (2,789 once invoked), scanned A, original, MIT.

A set of checks based on the Twelve-Factor App method, a collection of guidelines for building software services that are easier to deploy, scale, and operate.

In plain words
What is it for?
Use it to assess or improve cloud applications running in containers, Kubernetes, or serverless environments, including services stored in a monorepo (one repository containing multiple projects).
Why use it?
It reveals configuration, code-organization, deployment, and operational practices that can make a service harder to run reliably across development, testing, and production.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the shipworthy plugin — 66 skills, 7 commands, 3 hooks shipped together

Good fit Use it to assess or improve cloud applications running in containers, Kubernetes, or serverless environments, including services stored in a monorepo (one repository containing multiple projects).

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/vimalk0703/shipworthy/twelve-factor-app
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 Vimalk0703/shipworthy --skill twelve-factor-app
Clone the repo
git clone --depth 1 https://github.com/Vimalk0703/shipworthy

Made for: Claude Code.

Or install shipworthy, the plugin that ships this one along with the rest of its 66 skills, 7 commands, 3 hooks.

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 twelve-factor-app

README.md
[![agentmods](https://agentmods.dev/badge/skills/vimalk0703/shipworthy/twelve-factor-app.svg)](https://agentmods.dev/skills/vimalk0703/shipworthy/twelve-factor-app)
Your own site
<a href="https://agentmods.dev/skills/vimalk0703/shipworthy/twelve-factor-app"><img src="https://agentmods.dev/badge/skills/vimalk0703/shipworthy/twelve-factor-app.svg" alt="Measured on agentmods" height="20"></a>
Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,789 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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 $0.00044 $0.02789
Opus 5 $0.00022 $0.01394
Sonnet 5 $0.00009 $0.00558
Haiku 4.5 $0.00004 $0.00279

Measured 8d ago against content hash 498a8642076d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

twelve-factor-app scanned grade A with 1 finding 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 8d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

- [ ] No dependency is fetched from an unversioned URL or a curl pipe to shell.
skills/architecture/twelve-factor-app/SKILL.md · 278 lines

How it starts

The opening of the file, as written. The whole thing — 278 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Twelve-Factor App (Modern 2025 Interpretation)

Core Principle

The Twelve-Factor App methodology describes how to build software-as-a-service applications that are portable, scalable, and operationally mature. Originally written in 2011 by Heroku engineers, these principles remain foundational -- but the implementation details have evolved with containers, Kubernetes, and serverless.


I. Codebase -- One Codebase, One App

Principle: One codebase tracked in version control, many deploys (staging, production, etc.).

Modern interpretation:

  • One Git repository per deployable service (monorepo is acceptable if each service has clear boundaries and independent deployment).
  • The same codebase is deployed to dev, staging, and production. Differences between environments come from configuration, not code branches.
  • Feature flags control behavior differences, not separate codebases.

Actionable checks:

  • Every service has exactly one repository (or one clear path in a monorepo).
  • There is no "production branch" that diverges from main -- main is always deployable.
  • Environment-specific behavior is controlled by config or feature flags, never by code branching.

II. Dependencies -- Explicitly Declare and Isolate

Principle: Never rely on system-level packages. Declare all dependencies explicitly and isolate them.

Modern interpretation:

  • Use lockfiles: package-lock.json, poetry.lock, go.sum, Cargo.lock.
  • Container images pin base image versions: FROM node:20.11.0-slim, not FROM node:latest.
  • Do not install tools globally in CI/CD -- declare them in the project.

Actionable checks:

  • A lockfile exists and is committed to version control.
  • Dockerfiles use pinned base image digests or exact version tags.
  • npm install / pip install / go build works from a clean clone with no manual steps.
  • No dependency is fetched from an unversioned URL or a curl pipe to shell.

III. Config -- Store Config in the Environment

Read the full file on GitHub · 278 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. 8d ago First seen · 278 lines · 44 tokens per session scan A 498a8642076d

Subscribe to this mod's changes

twelve-factor-app is a skill published in the GitHub repository Vimalk0703/shipworthy (7 stars, last pushed 5mo ago), licensed MIT. It adds 44 tokens to every session and 2,789 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Related

Other skills, from other repositories