stacktower

Stacktower

Inspired by XKCD #2347, Stacktower renders dependency graphs as physical towers where blocks rest on what they depend on. Your application sits at the top, supported by libraries below—all the way down to that one critical package maintained by some dude in Nebraska.

📖 Read the full story at stacktower.io

⚠️ Note: The ordering algorithms are still experimental and may not produce nicely stacked towers for projects with a large number of dependencies. Results can vary. We're actively working on improvements.

Installation

Homebrew (macOS/Linux)

brew install matzehuels/tap/stacktower

Go

go install github.com/matzehuels/stacktower@latest

From Source

git clone https://github.com/matzehuels/stacktower.git
cd stacktower
go build -o bin/stacktower ./cmd/stacktower

Quick Start

# Render the included Flask example (XKCD-style tower is the default)
stacktower render examples/real/flask.json -o flask.svg

Usage

Stacktower works in two stages: parse dependency data from package registries or manifest files, then render visualizations.

Parsing Dependencies

The parse command auto-detects whether you're providing a package name or a manifest file:

stacktower parse <language> <package-or-file> [flags]

Supported languages: python, rust, javascript, ruby, php, java, go

From Package Registries

stacktower parse python fastapi -o fastapi.json                  # PyPI
stacktower parse rust serde -o serde.json                        # crates.io
stacktower parse javascript yargs -o yargs.json                  # npm
stacktower parse ruby rails -o rails.json                        # RubyGems
stacktower parse php monolog/monolog -o monolog.json             # Packagist
stacktower parse java com.google.guava:guava -o guava.json       # Maven Central
stacktower parse go github.com/gin-gonic/gin -o gin.json         # Go Module Proxy

From Manifest Files (Auto-Detected)

stacktower parse python examples/manifest/poetry.lock -o deps.json
stacktower parse python examples/manifest/requirements.txt -o deps.json
stacktower parse rust examples/manifest/Cargo.toml -o deps.json
stacktower parse javascript examples/manifest/package.json -o deps.json
stacktower parse ruby examples/manifest/Gemfile -o deps.json
stacktower parse php examples/manifest/composer.json -o deps.json
stacktower parse java examples/manifest/pom.xml -o deps.json
stacktower parse go examples/manifest/go.mod -o deps.json

When the argument exists on disk or matches a known manifest filename, Stacktower automatically parses it as a manifest.

The project name (root node) is auto-detected from the manifest or a sibling file:

• Cargo.toml: [package].name
• go.mod: module directive
• package.json: name field
• composer.json: name field
• pom.xml: groupId:artifactId
• poetry.lock / requirements.txt: pyproject.toml (sibling)
• Gemfile: *.gemspec (sibling)

Use --name to override the auto-detected name:

stacktower parse python requirements.txt --name="my-project" -o deps.json
stacktower parse ruby Gemfile -n my-rails-app -o deps.json

Metadata Enrichment

By default, Stacktower enriches packages with GitHub metadata (stars, maintainers, last commit) for richer visualizations. Set GITHUB_TOKEN to enable this:

export GITHUB_TOKEN=your_token
stacktower parse python fastapi -o fastapi.json

# Skip enrichment if you don't have a token
stacktower parse python fastapi --skip-enrich -o fastapi.json

Rendering

The render command generates visualizations from parsed JSON graphs:

stacktower render <file> [flags]

This is a shortcut that combines layout and visualize in one step. For more control, you can run them separately:

# Two-step workflow with intermediate layout
stacktower layout examples/real/flask.json -o flask.layout.json
stacktower visualize flask.layout.json -o flask.svg

Visualization Types

# Hand-drawn XKCD-style tower (default)
stacktower render examples/real/flask.json -o flask.svg

# Disable hand-drawn effects for a cleaner look
stacktower render examples/real/serde.json --style simple --randomize=false --popups=false -o serde.svg

# Traditional node-link diagram (uses Graphviz DOT)
stacktower render examples/real/yargs.json -t nodelink -o yargs.svg

Output Formats

# SVG output (default)
stacktower render examples/real/flask.json -o flask.svg

# JSON layout export (for external tools or re-rendering)
stacktower render examples/real/flask.json -f json -o flask.json

# PDF output
stacktower render examples/real/flask.json -f pdf -o flask.pdf

# PNG output (2x scale by default)
stacktower render examples/real/flask.json -f png -o flask.png

# Multiple formats at once (outputs flask.svg, flask.json, flask.pdf)
stacktower render examples/real/flask.json -f svg,json,pdf -o flask

Output path behavior:

• No -o: Derives from input (input.json → input.<format>)
• Single format: Uses exact path (-o out.svg → out.svg)
• Multiple formats: Strips extension, adds format (-o out -f svg,json → out.svg, out.json)

Note: PDF and PNG output requires librsvg:

• macOS: brew install librsvg
• Linux: apt install librsvg2-bin

Included Examples

The repository ships with pre-parsed graphs so you can experiment immediately:

# Real packages with full metadata (XKCD-style by default)
stacktower render examples/real/flask.json -o flask.svg
stacktower render examples/real/serde.json -o serde.svg
stacktower render examples/real/yargs.json -o yargs.svg

# With Nebraska guy ranking
stacktower render examples/real/flask.json --nebraska -o flask.svg

# Synthetic test cases
stacktower render examples/test/diamond.json -o diamond.svg

Options Reference

Global Options

Parse Options

Render Options

Tower Options

JSON Format

The render layer accepts a simple JSON format, making it easy to visualize any directed graph—not just package dependencies. You can hand-craft graphs for component diagrams, callgraphs, or pipe output from other tools.

Minimal Example

{
  "nodes": [{ "id": "app" }, { "id": "lib-a" }, { "id": "lib-b" }],
  "edges": [
    { "from": "app", "to": "lib-a" },
    { "from": "lib-a", "to": "lib-b" }
  ]
}

Required Fields

Optional Fields

Recognized meta Keys

These keys are read by specific render flags. All are optional—missing keys simply disable the corresponding feature.

The --detailed flag (node-link only) displays all meta keys in the node label.

How It Works

1. Parse — Fetch package metadata from registries or local manifest files
2. Reduce — Remove transitive edges to show only direct dependencies
3. Layer — Assign each package to a row based on its depth
4. Order — Minimize edge crossings using branch-and-bound with PQ-tree pruning
5. Layout — Compute block widths proportional to downstream dependents
6. Render — Generate output in SVG, JSON, PDF, or PNG format

The ordering step is where the magic happens. Stacktower uses an optimal search algorithm that guarantees minimum crossings for small-to-medium graphs. For larger graphs, it gracefully falls back after a configurable timeout.

GitHub Authentication

For parsing repositories directly from GitHub, you can authenticate using the device flow:

# Login with GitHub (opens browser for device authorization)
stacktower github login

# Check current session
stacktower github whoami

# Logout
stacktower github logout

# Parse a manifest from a GitHub repository
stacktower parse github owner/repo -o deps.json

Environment Variables

Caching

HTTP responses are cached in ~/.cache/stacktower/ with a 24-hour TTL. Use --no-cache to disable caching for a single request.

# Clear the entire cache
stacktower cache clear

# Show cache directory path
stacktower cache path

Using as a Library

Stacktower can be used as a Go library for programmatic graph visualization.

import (
    "github.com/matzehuels/stacktower/pkg/core/dag"
    "github.com/matzehuels/stacktower/pkg/core/dag/transform"
    "github.com/matzehuels/stacktower/pkg/core/render/tower/layout"
    "github.com/matzehuels/stacktower/pkg/core/render/tower/sink"
)

// Build a graph
g := dag.New(nil)
g.AddNode(dag.Node{ID: "app", Row: 0})
g.AddNode(dag.Node{ID: "lib", Row: 1})
g.AddEdge(dag.Edge{From: "app", To: "lib"})

// Normalize and render
transform.Normalize(g)
l := layout.Build(g, 800, 600)
svg := sink.RenderSVG(l, sink.WithGraph(g), sink.WithPopups())

📚 Full API documentation on pkg.go.dev

Key packages:

• pkg/core/dag — DAG data structure and crossing algorithms
• pkg/core/dag/transform — Graph normalization pipeline
• pkg/core/render/tower — Layout, ordering, and rendering
• pkg/core/deps — Dependency resolution from registries
• pkg/pipeline — Complete parse → layout → render pipeline

Contributing

See CONTRIBUTING.md for guidelines on adding new languages, manifest parsers, or output formats.

Development

make install-tools  # Install required tools (golangci-lint, goimports, govulncheck)
make check          # Run all CI checks locally (fmt, lint, test, vuln)
make build          # Build binary to bin/stacktower

Commit messages follow Conventional Commits.

Learn More

• 📖 stacktower.io — Interactive examples and the full story behind tower visualizations
• 🐛 Issues — Bug reports and feature requests

License

Apache-2.0