Open Source License Compatibility Checker

Select Licenses

2 selected
Permissive
Source Available
Weak Copyleft
Strong Copyleft
Content Licenses

Project Type

0
Compatible
pairs
0
Incompatible
pairs
1
Conditional
pairs

Pair Analysis

⚠ Pitfall Warnings

MIT + GPL 3.0:The combined work must be distributed under GPL-3.0. All recipients receive GPL-3.0 rights.

Recommended Outbound Licenses

MIT + GPL 3.0:GPL-3.0

This tool provides general guidance based on widely accepted license compatibility analysis (FSF, OSI, and community resources). It is not legal advice. For commercial use or ambiguous cases, consult a qualified attorney. License compatibility can depend on jurisdiction, specific use case, and exact license versions used.

What This Tool Does

Open Source License Compatibility Checker is built for deterministic developer and agent workflows.

Check whether two or more open source licenses are compatible. Get verdict, requirements, and recommended outbound license for MIT, GPL, Apache, LGPL, MPL, and more.

Use How to Use for execution steps and FAQ for constraints, policies, and edge cases.

Last updated:

This tool is provided as-is for convenience. Output should be verified before use in any production or critical context.

Agent Invocation

Best Path For Builders

Browser workflow

Runs instantly in the browser with private local processing and copy/export-ready output.

Browser Workflow

This tool is optimized for instant in-browser execution with local data handling. Run it here and copy/export the output directly.

/license-compatibility-checker/

For automation planning, fetch the canonical contract at /api/tool/license-compatibility-checker.json.

How to Use Open Source License Compatibility Checker

  1. 1

    Select your licenses

    Click license buttons to toggle them on/off. Licenses are grouped by type: permissive (MIT, Apache, BSD), weak copyleft (MPL, LGPL, EPL), strong copyleft (GPL, AGPL), and content (CC). Select all licenses used in your project or dependencies.

  2. 2

    Set your project type

    Choose library, application, or SaaS. SaaS/network services trigger AGPL-3.0 copyleft — if your project runs as a hosted service and uses AGPL-licensed code, you must publish source code for users who interact with it over the network.

  3. 3

    Review pair verdicts

    Each license pair shows a Compatible (green), Incompatible (red), or Conditional (amber) verdict. Click any pair to expand detailed notes explaining what requirements apply and what the recommended outbound license is for the combined work.

  4. 4

    Use the matrix for 3+ licenses

    When 3 or more licenses are selected, a visual compatibility matrix is shown. Green ✓ = compatible, red ✗ = incompatible, amber ~ = conditional. Hover cells to see notes. This quickly spots problematic combinations across an entire dependency set.

  5. 5

    Check pitfall warnings

    The Pitfall Warnings section highlights the most common mistakes — like combining GPL-2.0 with Apache 2.0 (incompatible!), or using CC licenses for code. Address each warning before shipping or open-sourcing your project.

Frequently Asked Questions

What is the License Compatibility Checker?
A free tool that checks whether open source licenses can be combined in one project. It shows compatible, incompatible, or conditional verdicts per pair, lists requirements like attribution or source disclosure, and warns about common pitfalls like GPL-2.0 + Apache 2.0 incompatibility.
How do I use License Compatibility Checker?
Select two or more licenses from the list (MIT, Apache 2.0, GPL-2.0, GPL-3.0, LGPL, MPL, AGPL, BSD, and more), choose your project type (library, application, or SaaS), then review the per-pair verdicts. For 3+ licenses, a visual compatibility matrix is shown. Click any pair row to see detailed notes and warnings.
Why are GPL-2.0 and Apache 2.0 incompatible?
Apache 2.0 includes patent retaliation and termination clauses that the FSF considers 'additional restrictions' prohibited by GPL-2.0. The fix: use GPL-3.0 instead, which was specifically updated to be compatible with Apache 2.0.
What does 'conditional' compatibility mean?
Conditional means the licenses can be combined, but you must follow specific rules — for example, the combined work may need to be distributed under the stronger (copyleft) license, or you must provide source code. The tool explains exactly what is required for each pair.
Does project type (library vs. SaaS) affect compatibility?
Yes, especially for AGPL-3.0. AGPL-3.0 requires publishing source code even when running as a network service — a requirement that doesn't apply to GPL-3.0. For SaaS/network services, AGPL-3.0 components trigger strict source disclosure obligations.