ExplainThisRepo

The fastest way to understand any codebase in plain English using real project signals. Not blind AI guessing.

ExplainThisRepo analyzes real project signals; configs, entrypoints, manifests, dependencies graph, file structure and high-signal files producing a clear, structured EXPLAIN.md that explains what the codebase actually does and how it is organized in plain English.

Key Features

• Understand any GitHub repository in seconds
• Derives architectural summaries from repository structure and code signals. Not blind AI guessing
• Deterministic repo signal extractor that feeds LLMs correctly. Signals first. LLM second
• Translates complex code structures into plain English
• Speeds up understanding of unfamiliar codebases
• Solves the "garbage in, garbage out" problem specifically for codebases
• Extract architecture signals from configs, entrypoints, and manifests
• System map that shows you where to start, what matters and what to ignore
• Works with GitHub repositories, Local repositories, GitHub directories, local directories, GitHub files and local files
• Supports private repositories and monorepos
• Zero-cloning and remote analysis
• Outputs the explanation to an EXPLAIN.md file in your current directory, prints it directly in the terminal, or a specified output file (.txt, .pdf, .docx, .md)
• Multiple explanation modes (quick, simple, detailed)
• Additional tools: stack detection, repo map

Installation

Option 1: install with pip (Python source version):

Requirements: Python 3.9+

pip install explainthisrepo
explainthisrepo owner/repo

# explainthisrepo .
# explainthisrepo ./path/to/directory
# explainthisrepo ./path/to/file.py
# explainthisrepo owner/repo/path/to/file.py
# explainthisrepo owner/repo/path/to/directory

Alternatively,

pipx install explainthisrepo
explainthisrepo owner/repo

After installation, use any of the available commands:

explainthisrepo owner/repo
explain-this-repo owner/repo
etr owner/repo

To install support for specific models:

pip install explainthisrepo[gemini]
pip install explainthisrepo[openai]
pip install explainthisrepo[anthropic]
pip install explainthisrepo[groq]

Replace owner/repo with the GitHub repository identifier (e.g., facebook/react, torvalds/linux).

Option 2: Install with npm (prebuilt binary, no Python required)

Install globally and use forever:

npm install -g explainthisrepo
explainthisrepo owner/repo

Details

# explainthisrepo .
# explainthisrepo ./path/to/directory
# explainthisrepo ./path/to/file.py
# explainthisrepo owner/repo/path/to/file.py
# explainthisrepo owner/repo/path/to/directory

Or without install:

npx explainthisrepo owner/repo

Details

# npx explainthisrepo .
# npx explainthisrepo ./path/to/directory
# npx explainthisrepo ./path/to/file.py
# npx explainthisrepo owner/repo/path/to/file.py
# npx explainthisrepo owner/repo/path/to/directory

How it works

ExplainThisRepo uses a hybrid architecture:

• Python → core implementation (analysis, prompts, providers, output)
• npm → launches prebuilt native binaries (no Python install required)
• pip → installs the full Python package

The npm and pip versions run the same core engine.

Option 3: Download standalone binary

Prebuilt standalone binaries are available for macOS, Linux, and Windows.

Standalone binaries require no Python or Node installation and run as a single executable.

Download the latest release:

github.com/calchiwo/ExplainThisRepo/releases/latest

Or install directly:

macOS

curl -L https://github.com/calchiwo/ExplainThisRepo/releases/latest/download/explainthisrepo-darwin-arm64 -o explainthisrepo
chmod +x explainthisrepo

Linux

curl -L https://github.com/calchiwo/ExplainThisRepo/releases/latest/download/explainthisrepo-linux-x64 -o explainthisrepo
chmod +x explainthisrepo

Windows (PowerShell)

curl -L https://github.com/calchiwo/ExplainThisRepo/releases/latest/download/explainthisrepo-win-x64.exe -o explainthisrepo.exe

Configuration

ExplainThisRepo supports multiple LLM models:

• Gemini
• OpenAI
• Ollama (local or cloud-routed)
• Anthropic
• Groq
• OpenRouter

Use the built-in init command to configure your preferred model:

explainthisrepo init
# or npx explainthisrepo init

For details about how initialization works, see docs/INIT.md.

GitHub token Access (Private Repos & Rate Limits)

ExplainThisRepo supports GitHub authentication for:

• Accessing private repositories
• Higher API rate limits on public repositories

Run:

explainthisrepo init

For step-by-step instructions, see docs/GITHUB_TOKEN.md

Flag options

• (no flag) → Full repository explanation written to EXPLAIN.md

• --quick → One-sentence summary

• --simple → Short, simplified explanation

• --detailed → Deeper explanation including structure and architecture

• --stack → Tech stack breakdown from repo signals

• --map → System map for understanding a codebase before changing it

• --version → Check installed CLI version

• --help → Show usage guide

• --doctor → Check system health and active model diagnostics

• --llm → Override provider selection

• --output / -o → Specify output file or directory (default: EXPLAIN.md)

Flexible Input Types

Accepts various formats for repository input, full GitHub URLs (with or without https), owner/repo format, issue links, query strings, and SSH clone links

explainthisrepo https://github.com/owner/repo
explainthisrepo github.com/owner/repo
explainthisrepo https://github.com/owner/repo/issues/123
explainthisrepo https://github.com/owner/repo?tab=readme
explainthisrepo git@github.com:owner/repo.git
explainthisrepo owner/repo/path/to/directory
explainthisrepo owner/repo/path/to/file.py
explainthisrepo .
explainthisrepo ./path/to/directory
explainthisrepo ./path/to/file.py

GitHub inputs are normalized internally to owner/repo.

CLI aliases

ExplainThisRepo ships with multiple command names that all map to the same entrypoint:

• explainthisrepo → primary command
• explain-this-repo → readable alias
• etr → short alias for faster typing

All three commands run the same tool and support the same flags and modes.

explainthisrepo owner/repo
explain-this-repo owner/repo
etr owner/repo

Model selection

The --llm flag selects which configured model backend to use for the current command.

explainthisrepo owner/repo --llm gemini
explainthisrepo owner/repo --llm openai
explainthisrepo owner/repo --llm ollama
explainthisrepo owner/repo --llm anthropic
explainthisrepo owner/repo --llm openrouter
explainthisrepo owner/repo --llm groq

--llm works with all modes (--quick, --simple, --detailed).

Command line usage

Default

Writes a full explanation to EXPLAIN.md:

explainthisrepo owner/repo
#e.g. explainthisrepo vercel/next.js

Quick mode

Prints a one-sentence summary to stdout:

explainthisrepo owner/repo --quick
# explainthisrepo facebook/react --quick

$ explainthisrepo vercel/next.js --quick

Next.js is a React framework that provides server-side rendering,
file-based routing, API routes, and build tooling for fullstack
web applications.

---

Detailed mode

Writes a more detailed explanation of repository structure and architecture:

explainthisrepo owner/repo --detailed

---

Simple mode

Prints a short, simplified explanation to stdout. No files are written.

explainthisrepo owner/repo --simple

---

Stack detector

Tech stack breakdown detected from repo signals. No LLM calls are made.

explainthisrepo owner/repo --stack

Repo map

Navigation system map for understanding unfamiliar codebases that shows you where to start, what matters and what to ignore before touching it:

explainthisrepo owner/repo --map
explainthisrepo . --map

By default, repo map mode writes to REPO_MAP.md.

The map focuses on:

• where to start reading
• the likely main flow through the project
• important files and why they matter
• visible architecture boundaries
• files or folders to ignore first
• open questions that cannot be determined from repo signals

Local Directory Analysis

ExplainThisRepo can analyze local directories directly in the terminal, using the same modes and output formats as GitHub repositories

explainthisrepo .
explainthisrepo ./path/to/directory

This works with all existing modes:

explainthisrepo . --quick
explainthisrepo . --simple
explainthisrepo . --detailed
explainthisrepo . --stack
explainthisrepo . --map

When analyzing a local directory:

• Repository structure is derived from the filesystem
• High signal files (configs, entrypoints, manifests) are extracted locally
• No GitHub APIs calls are made
• All prompts and outputs remain identical

This allows analysis of projects directly from the local filesystem, without requiring a GitHub repository.

File Analysis

ExplainThisRepo analyzes individual files directly

explainthisrepo ./path/to/file.py

Supports all explanation modes:

explainthisrepo ./file.py --quick
explainthisrepo ./file.py --simple
explainthisrepo ./file.py --detailed

When analyzing a file:

• The file is read safely with encoding and size limits
• Structure and basic signals (size, lines, type) are extracted
• The explanation focuses on purpose, logic, and behavior
• This makes it easy to understand unfamiliar files without scanning entire repositories.

GitHub File Analysis

ExplainThisRepo can analyze a single file directly from a GitHub repository without cloning it.

explainthisrepo owner/repo/path/to/file.py

Supports all explanation modes:

explainthisrepo owner/repo/path/to/file.py --quick
explainthisrepo owner/repo/path/to/file.py --simple
explainthisrepo owner/repo/path/to/file.py --detailed

When analyzing a GitHub file:

• The file is fetched directly via the GitHub API
• Raw bytes are passed into a unified ingestion pipeline
• Binary detection, decoding, and size limits are handled in one place
• File ingestion is identical to local file analysis
• The explanation focuses on the file’s purpose, logic, and behavior
• This removes divergence between local and GitHub file handling

Input format must be:

explainthisrepo owner/repo/path/to/file

This is different from local file analysis:

explainthisrepo ./path/to/file.py

GitHub Directory Analysis

ExplainThisRepo can analyze a specific directory inside a GitHub repository without cloning it.

explainthisrepo owner/repo/path/to/directory

Supports all explanation modes:

explainthisrepo owner/repo/path/to/directory --quick
explainthisrepo owner/repo/path/to/directory --simple
explainthisrepo owner/repo/path/to/directory --detailed

When analyzing a GitHub directory:

• Directory contents are fetched via the GitHub API
• Only structure and metadata are used (no full repo fetch)
• Signals include files, subdirectories, and extension distribution
• The explanation focuses on the directory’s role and structure

--stack is not supported for directory targets.

Custom output

--output, -o → Specify output file or directory (default: EXPLAIN.md)

Write to a specific file:

explainthisrepo owner/repo --output notes.md

Write to a nested path:

explainthisrepo owner/repo --output path/to/file.md

Write to a directory (creates EXPLAIN.md inside):

explainthisrepo owner/repo --output path/to/directory

Version

Check the installed CLI version:

explainthisrepo --version

Diagnostics

Use the --doctor flag to verify the environment, network connectivity, and API key configuration:

explainthisrepo --doctor

Termux (Android) install notes

Termux has some environment limitations that can make pip install explainthisrepo fail to create the explainthisrepo command in $PREFIX/bin.

However, it's recommended you install using:

pip install --user -U explainthisrepo

Make sure your user bin directory is on your PATH:

export PATH="$HOME/.local/bin:$PATH"

Tip: Add the PATH export to your ~/.bashrc or ~/.zshrc so it persists.

Alternative (No PATH changes)

If you do not want to modify PATH, you can run ExplainThisRepo as a module:

python -m explain_this_repo owner/repo

Gemini support on Termux

Installing Gemini support may require building Rust-based dependencies on Android, which can take time on first install:

pip install --user -U "explainthisrepo[gemini]"

For mobile environments like Termux where compiling Python dependencies can be slow, you can also run ExplainThisRepo using the Node.js version:

npx explainthisrepo owner/repo

Special Thanks

• @Spectra010s for implementing the Node.js version of ExplainThisRepo and improving installation support for mobile environments like Termux
• @HalxDocs for implementing the --detailed mode for deeper architectural explanations

Contributions

Contributions are welcome!

If you find a bug, have an idea, or want to improve the tool:

• See CONTRIBUTING for setup and guidelines
• Open an issue for bugs/feature requests
• Or submit a pull request for fixes/improvements

License

This project is licensed under the MIT License. See the LICENSE file for details.

Author

Caleb Wodi

• Email: caleb@explainthisrepo.com
• LinkedIn: @calchiwo
• Twitter: @calchiwo