API Mapper Skills

Agent skills for reverse-engineering undocumented APIs from websites and Android APKs.

This repository contains two skills that trace endpoints, authentication, request construction, serialization, signing, and multi-step flows. Both produce implementation-ready API documentation and small replay scripts for behavior that cannot be described as a plain HTTP request.

Skills

Skill	Target	Primary analysis path
api-mapper	Websites	Chrome CDP capture, curl probing, and JavaScript bundle analysis
apk-api-mapper	Android APKs	Hermes/JavaScript bundles for React Native; JADX for Android-native code and bridges

The APK mapper follows the layer that owns each request. React Native Hermes bundles are analyzed with hermes-dec, plain JavaScript bundles are traced directly, and JADX is used when behavior lives in Android code or crosses a native bridge. apktool is an optional fallback for decoded resources or broad smali searches.

Requirements

Install only the tools needed for the selected skill and target:

• Website mapping: Python 3, Google Chrome, and curl or curl.exe
• APK mapping: an APK file or JADX project, plus hermes-dec for Hermes bytecode, JADX MCP for Android-native analysis, or apktool when decoded resources or broad smali searches are needed

Missing optional tools are not installed automatically.

Install

Install either or both skills with the skills CLI:

npx -y skills add github.com/11philip22/api-mapper-skill -a codex --global --skill api-mapper
npx -y skills add github.com/11philip22/api-mapper-skill -a codex --global --skill apk-api-mapper

Replace codex with opencode or claude to install for another supported agent.

Usage

Map a website:

Use the api-mapper skill to reverse-engineer and document https://example.com.

Map an APK:

Use the apk-api-mapper skill to reverse-engineer and document the APIs used by app.apk.

An APK may instead be supplied through an open JADX project. When native analysis is required, the skill uses the project's read-only JADX MCP integration.

Note

Website mapping opens a visible Chrome session. User input is only needed for walls such as missing credentials, CAPTCHAs, or blocking rate limits.

Generated output

Results are written into the target project, not this skill repository:

docs/apis/
  README.md
  {area}.md
scripts/flows/
  {flow}.py                 # only for non-trivial reproducible flows
artifacts/{timestamp}/      # website captures and JavaScript bundles
artifacts/apk/{timestamp}/  # APK artifacts, only when extraction is needed

Documentation is language-agnostic and includes evidence, confidence, request schemas, and the state shared across multi-request flows. Replay scripts run without reopening Chrome or JADX.

Repository layout

api-mapper/
  SKILL.md
  agents/openai.yaml
  references/
apk-api-mapper/
  SKILL.md
  agents/openai.yaml
  references/