License Checker
Verify package licenses and ensure compliance with your project license
About this ToolHow it works, benefits & use casesTap to collapse
Open-source compliance comes down to one question: are your dependencies' licenses compatible with the license you ship under? This tool answers it in two modes. The Checker takes a list of "package-name LICENSE" lines, looks each license up in a database of common SPDX identifiers (MIT, Apache-2.0, BSD, ISC, the GPL and LGPL families, MPL-2.0, Unlicense, CC0, and more), and flags incompatibilities against your chosen project license — for example warning when a strong-copyleft GPL package sits inside an MIT project, or when a license is UNKNOWN/UNLICENSED. Each package shows its category (permissive, weak/strong copyleft, public domain), compatibility verdict, and any copyleft warnings, plus a summary and recommendations. The Generator produces a complete LICENSE file (MIT, Apache-2.0, and others) with your copyright year and owner filled in. Everything runs locally on the text you provide.
How to Use
- 1Choose the Checker or Generator tab at the top.
- 2In the Checker, select your project's license, then paste packages as "name LICENSE" lines (one per line) — or click "Load example".
- 3Click "Check license compatibility" to see counts, per-package categories, compatibility verdicts, and warnings.
- 4In the Generator, pick a license type and enter the copyright year and owner.
- 5Click "Generate LICENSE file" and copy or download the resulting LICENSE text.
Key Benefits
- Two tools in one: compatibility checker plus LICENSE-file generator
- Recognises common SPDX licenses with category and commercial-use metadata
- Flags incompatibilities against your chosen project license
- Warns on strong/weak copyleft and on UNKNOWN or UNLICENSED packages
- Summary stats: total, compatible, and issue counts at a glance
- Generates ready-to-ship LICENSE text with your year and owner
- Runs entirely on pasted text — no registry calls or uploads
Common Use Cases
- Auditing a dependency list for copyleft licenses before going closed-source
- Confirming third-party licenses are compatible with an MIT or Apache project
- Spotting packages with missing or unknown licenses that need manual review
- Generating a LICENSE file for a new open-source repository
- Teaching the difference between permissive, copyleft, and public-domain licenses
One per line: package-name LICENSE (e.g., react MIT)
License categories explained
- Permissive:
- Minimal restrictions, can be used in proprietary software (e.g., MIT, Apache)
- Weak Copyleft:
- Modifications to the library must be open source, but your code can be proprietary (e.g., LGPL)
- Strong Copyleft:
- Entire project must be open source (e.g., GPL)
- Public Domain:
- No restrictions whatsoever (e.g., Unlicense, CC0)
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One package per line as "package-name LICENSE", for example "react MIT" or "some-lib GPL-3.0". The first token is the package name and the second is its SPDX license identifier. Lines starting with # are ignored, and a missing license is treated as UNKNOWN.
Each license in the database carries a compatibility list. The checker compares every package's license against your selected project license's compatibility set; if it is not included, the package is flagged as potentially incompatible. UNKNOWN and UNLICENSED packages are always flagged for manual review.