license-trace

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Recursive Dependency License Tracer, Obligations Evaluator, and Outbound Compliance Auditor.

license-trace is a high-performance compliance tool designed to recursively inspect direct and transitive dependency graphs, compute aggregate legal obligations (lower-bound requirements), and verify whether a project can be safely distributed under a target open-source license (such as MIT or Apache-2.0).

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Key Features

• Multi-Ecosystem Auto-Detection: Seamlessly inspects Rust (Cargo), Node.js (npm), Python (pip/Poetry), and Go (go.mod) projects.
• Unified Tracing Interface: Inspect local folders (.), uninstalled registry packages (express), or public Git repositories from a single command.
• Strict SPDX AST Evaluation: Accurately processes complex expressions (OR takes the best permissible branch; AND combines strict requirements).
• Outbound License Compatibility Check: Detects Strong Copyleft (GPL), Network Copyleft (AGPL/SSPL), or Non-Commercial (BUSL/CC-BY-NC) conflicts against your intended release license.
• Obligations Lower-Bound Analysis: Calculates aggregated distribution requirements, including copyright notice attribution, source disclosure levels, and patent grants.
• Deep Path Tracing (why): Uses graph traversal to pinpoint every route through which an incompatible or unknown dependency entered your dependency tree.
• CI/CD Ready: Supports machine-readable JSON output, customizable exit codes, and automated compliance gates.

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Supported Ecosystems

Ecosystem	Manifest / Lockfile	License Discovery Strategy	Online Resolution
Rust / Cargo	Cargo.toml, Cargo.lock	cargo metadata (exact package fields)	crates.io API
Node.js / npm	package.json, package-lock.json	Manifest license / licenses fields	npm Registry API
Python	pyproject.toml, requirements.txt	.dist-info/METADATA, PEP 621 classifiers	PyPI JSON API
Go modules	go.mod, go.sum	go list -m -json all, embedded LICENSE files	Go Proxy / Repo

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Installation

Choose your preferred package manager or download pre-compiled binaries:

1. Via Cargo (Rust)

cargo install license-trace

2. Via Python / pip

pip install license-trace

3. Pre-compiled Binaries (GitHub Releases)

Download standalone executable archives for your OS and architecture from GitHub Releases:

• Linux: license-trace-v*-x86_64-unknown-linux-gnu.tar.gz / aarch64
• macOS: license-trace-v*-aarch64-apple-darwin.tar.gz (Apple Silicon) / x86_64 (Intel)
• Windows: license-trace-v*-x86_64-pc-windows-msvc.zip

4. Build from Source

git clone https://github.com/rikutoyamada01/license-trace.git
cd license-trace
cargo install --path .

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Usage & CLI Commands

Short Binary & Subcommand Aliases: You can also use lt instead of license-trace, and 1-letter subcommands: lt a (audit), lt t (trace), lt w (why), lt e (export). Flags also support short forms: -P (--prod-only), -i (--fail-on-incompatible), -u (--fail-on-unknown).

1. Project Compliance Audit (audit or trace . / a)

Audit a local project directory for compliance, obligations, and license compatibility against your target outbound license (defaults to MIT):

# Audit current directory (or `lt a`)
license-trace audit

# Audit specific directory with target outbound license
license-trace audit -p ./my-project --outbound "MIT OR Apache-2.0"

# Audit only production dependencies (exclude devDependencies)
license-trace audit -P

# CI Gate: fail if incompatible licenses or unknown licenses are detected
license-trace audit -i -u

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2. Universal Tracer (trace)

The trace command automatically identifies whether the target is a local directory, a remote registry package, or a Git URL.

A. Audit Current Project (Local)

license-trace trace .

To evaluate against a different outbound license (e.g. dual license):

license-trace trace . --outbound "MIT OR Apache-2.0"

To exclude development dependencies:

license-trace trace . --prod-only

B. Pre-screen Remote Packages (Registry)

Inspects an uninstalled package and its transitive dependency tree via registry APIs before adding it to your codebase:

license-trace trace express
license-trace trace lodash@4.17.21 --max-depth 3

C. Inspect Public Git Repositories

Clones a remote repository shallowly into a temporary directory and audits its dependency tree:

license-trace trace https://github.com/expressjs/express

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2. Trace Dependency Path (why)

Pinpoints exactly how a specific library was brought into your project:

license-trace why <package-name>

Example Output:

Dependency path search for 'nested-copyleft-tool':

    Found 2 path(s) from root [my-project@1.0.0]:

    Route 01: my-project -> direct-service@2.1.0 -> nested-copyleft-tool@0.4.1
    Route 02: my-project -> helper-utils@1.0.0 -> legacy-core@1.2.0 -> nested-copyleft-tool@0.4.1

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3. Output Formats

license-trace supports multiple visualization and export formats:

# Standard Terminal Audit Report (Default)
license-trace trace . --format audit

# Tabular Overview
license-trace trace . --format table

# Pure Dependency Tree
license-trace trace . --format tree

# Machine-readable JSON (for CI/CD pipelines)
license-trace trace . --format json

# Export third-party notice markdown directly
license-trace trace . --format markdown

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4. Export Third-Party Licenses File (export)

Generate a compliant THIRD_PARTY_LICENSES.md file for distribution and release artifacts:

license-trace export --output THIRD_PARTY_LICENSES.md

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Visual Report Sample (Auditing license-trace Itself)

Running license-trace trace . on this repository produces the following real-world audit:

$ license-trace trace .

=== License Trace & Compliance Audit ===
Target Outbound License : MIT
Audit Status            : [COMPATIBLE]
Summary                 : All dependencies are compatible with 'MIT'. Safe for distribution!

--- Dependency Tree ---
license-trace@0.1.0 [MIT]
|-- tokio@1.53.1 [MIT]
|   |-- windows-sys@0.61.2 [MIT OR Apache-2.0]
|   |   `-- windows-link@0.2.1 [MIT OR Apache-2.0]
|   |-- tokio-macros@2.7.2 [MIT]
|   |   |-- syn@3.0.3 [MIT OR Apache-2.0]
|   |   |   |-- unicode-ident@1.0.24 [(MIT OR Apache-2.0) AND Unicode-3.0]
|   |   |   `-- quote@1.0.47 [MIT OR Apache-2.0]
|   |   `-- quote@1.0.47 [MIT OR Apache-2.0] (deduped)
|   |-- socket2@0.6.5 [MIT OR Apache-2.0]
|   |-- pin-project-lite@0.2.17 [Apache-2.0 OR MIT]
|   |-- parking_lot@0.12.5 [MIT OR Apache-2.0]
|   |   `-- parking_lot_core@0.9.12 [MIT OR Apache-2.0]
|   `-- bytes@1.12.1 [MIT]
|-- reqwest@0.12.28 [MIT OR Apache-2.0]
|   |-- webpki-roots@1.0.9 [CDLA-Permissive-2.0]
|   |   `-- rustls-pki-types@1.15.1 [MIT OR Apache-2.0]
|   |-- url@2.5.8 [MIT OR Apache-2.0]
|   |   `-- idna@1.1.0 [Apache-2.0 OR MIT]
|   |       `-- idna_adapter@1.2.2 [Apache-2.0 OR MIT]
|   |           `-- icu_properties@2.3.0 [Unicode-3.0]
|   |-- tokio-rustls@0.26.4 [MIT OR Apache-2.0]
|   |   `-- rustls@0.23.43 [Apache-2.0 OR ISC OR MIT]
|   |       |-- rustls-webpki@0.103.14 [ISC]
|   |       `-- ring@0.17.14 [Apache-2.0 AND ISC]
|   `-- hyper-util@0.1.20 [MIT]
|-- petgraph@0.7.1 [MIT OR Apache-2.0]
|   `-- fixedbitset@0.5.7 [MIT OR Apache-2.0]
|-- serde_json@1.0.151 [MIT OR Apache-2.0]
|   `-- memchr@2.8.3 [Unlicense OR MIT]
|-- owo-colors@4.3.0 [MIT]
|-- comfy-table@7.2.2 [MIT]
|-- clap@4.6.6 [MIT OR Apache-2.0]
|-- spdx@0.10.9 [MIT OR Apache-2.0]
`-- anyhow@1.0.104 [MIT OR Apache-2.0]

--- License Breakdown ---
  - (MIT OR Apache-2.0) AND Unicode-3.0 : 1 package(s)
  - Apache-2.0                   : 5 package(s)
  - Apache-2.0 AND ISC           : 1 package(s)
  - Apache-2.0 OR BSL-1.0        : 1 package(s)
  - Apache-2.0 OR ISC OR MIT     : 2 package(s)
  - Apache-2.0 OR MIT            : 9 package(s)
  - Apache-2.0 WITH LLVM-exception OR Apache-2.0 OR MIT : 3 package(s)
  - BSD-3-Clause                 : 1 package(s)
  - CDLA-Permissive-2.0          : 1 package(s)
  - ISC                          : 2 package(s)
  - MIT                          : 27 package(s)
  - MIT OR Apache-2.0            : 106 package(s)
  - MIT OR Apache-2.0 OR LGPL-2.1-or-later : 1 package(s)
  - MIT OR Apache-2.0 OR Zlib    : 2 package(s)
  - Unicode-3.0                  : 18 package(s)
  - Unlicense OR MIT             : 1 package(s)
  - Zlib OR Apache-2.0 OR MIT    : 1 package(s)

--- Obligations (Lower Bound) ---
  Commercial Use       : Allowed
  Distribution         : Allowed
  Copyright / Notice   : Required
  Source Disclosure    : None (Permissive)

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License Categories & Compatibility Matrix

Category	Typical Licenses	Commercial Use	Source Disclosure	Compatibility with Permissive (MIT / Apache-2.0)
Permissive	MIT, Apache-2.0, BSD, ISC, 0BSD, Unlicense	Yes	None	Compatible
Weak Copyleft	LGPL, MPL-2.0, EPL, CDDL, CC-BY-SA	Yes	Library-level	Warning (Must retain unmodified dynamic links)
Strong Copyleft	GPL-2.0, GPL-3.0	Yes	Project-wide	Incompatible (Viral source disclosure)
Network Copyleft	AGPL-3.0, SSPL	Yes	Network-triggered	Incompatible (SaaS disclosure trigger)
Non-Commercial	CC-BY-NC, BUSL-1.1	No	Varies	Incompatible (Commercial distribution forbidden)
Unknown	Unrecognized / Custom	Manual Review	Unknown	Needs Review

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CI / CD Integration

Use exit codes to enforce compliance gates in continuous integration:

Exit Codes

• 0: Compatible (Audit passed)
• 1: Incompatible license constraints detected
• 2: Unknown licenses require manual review

GitHub Actions Workflow Example

name: License Compliance Audit

on:
  push:
    branches: [ main ]
  pull_request:
    branches: [ main ]

jobs:
  license-check:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout Code
        uses: actions/checkout@v4

      - name: Setup Rust
        uses: dtolnay/rust-toolchain@stable

      - name: Install license-trace
        run: cargo install --path .

      - name: Run Compliance Audit
        run: |
          license-trace trace . \
            --outbound MIT \
            --prod-only \
            --fail-on-incompatible \
            --fail-on-unknown

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Contributing

Contributions are welcome. Please ensure that all pull requests maintain 100% test coverage and follow Rust standard formatting (cargo fmt and cargo clippy).

cargo test
cargo clippy -- -D warnings

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License

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