Wp Plugin Directory Guidelines

Overview

Authoritative reference for the 18 WordPress.org Plugin Directory guidelines. Covers GPL licensing, plugin naming/trademark rules, trialware restrictions, and all other submission requirements.

When to use

Use this skill when you need to:

• Review a WordPress plugin for compliance with the WordPress.org Plugin Directory guidelines
• Check GPL license compatibility for a plugin or its bundled libraries
• Verify license headers in plugin files
• Identify common guideline violations before submission
• Answer questions about what is or is not allowed on WordPress.org
• Evaluate premium/upsell flows, license checks, or freemium positioning
• Review "teaser" or "preview" UI for trialware violations

Inputs required

• Plugin source code (or specific files to review)
• Optional: plugin readme and plugin header metadata for naming and license checks

Procedure

• Check the plugin's license header against the Valid License Headers section below.
• Walk through the 18 Guidelines checklist, paying special attention to Guidelines 1, 4, 5, 7, 8, and 17.
• Confirm trialware/freemium compliance using the checklist in guideline-review-checklist.md (Guideline 5 section).
• For bundled third-party code, verify license compatibility against GPL-Compatible Licenses (Quick) below.
• Flag matches from Common GPL Violations (Quick) below.
• For edge cases, consult the detailed references and the GNU GPL FAQ.

18-Guideline Review Checklist

Use the detailed, per-guideline checklist in guideline-review-checklist.md. Load this reference file only when a full guideline audit is requested.

GPL Compliance (Guideline 1 in Detail)

Use gpl-compliance.md for full license tables, compatibility nuances, and examples. Keep this inline section as a quick decision aid.

Verification (Licensing)

• Every licensing-related issue must cite Guideline 1 and include the file path and exact license string.
• Confirm compatibility claims against GPL-Compatible Licenses (Quick) and escalate ambiguous licenses.

Failure modes (Licensing)

• If a license is not clearly GPL-compatible, do not guess. Check the GNU license list.
• For dual-license packages, verify both licenses and redistribution terms.

Quick Reference: WordPress GPL Requirements

• WordPress is GPLv2 or later.
• Plugins distributed on WordPress.org must be 100% GPL-compatible (code and assets).
• Include a valid License: header and License URI: in the main plugin file.
• Do not add restrictions that conflict with GPL freedoms.

Valid License Headers

GPL Versions Summary

| Version | Year | Key Addition |

|---------|------|--------------|

| GPLv1 | 1989 | Base copyleft: share-alike for modifications |

| GPLv2 | 1991 | "Liberty or death" clause (Section 7), clearer distribution terms |

| GPLv3 | 2007 | Anti-tivoization, explicit patent grants, compatibility provisions |

WordPress uses GPLv2 or later, meaning plugins can use GPLv2, GPLv3, or "GPLv2 or later".

For full license texts, see:

• GNU General Public License v1
• GNU General Public License v2
• GNU General Public License v3

License Compliance Checklist

When reviewing a plugin, verify:

• [ ] Main plugin file has a valid License: header (e.g., GPL-2.0-or-later, GPL-2.0+, GPLv2 or later)
• [ ] Main plugin file has a License URI: header pointing to the GPL text
• [ ] If bundled libraries exist, each has a GPL-compatible license
• [ ] No "split licensing" (e.g., code GPL but premium features proprietary)
• [ ] No additional restrictions beyond what GPL allows
• [ ] No clauses restricting commercial use, modification, or redistribution
• [ ] No obfuscated code (violates the spirit of source code availability)

Valid License Headers for WordPress Plugins

License: GPL-2.0-or-later
License URI: https://www.gnu.org/licenses/gpl-2.0.html

License: GPL-3.0-or-later
License URI: https://www.gnu.org/licenses/gpl-3.0.html

License: GPLv2 or later
License URI: https://www.gnu.org/licenses/gpl-2.0.html

GPL-Compatible Licenses (Quick)

• Safe defaults: GPL-2.0-or-later, GPL-3.0-or-later.
• Commonly accepted permissive families: MIT/Expat, BSD, ISC, zlib, Boost.
• Conditional compatibility requires care: Apache-2.0 and MPL-2.0 (verify usage context).
• For full accepted and rejected identifiers, use gpl-compliance.md.

Common GPL Violations (Quick)

• Split licensing that restricts distributed code.
• Obfuscated or non-corresponding source distribution.
• Restrictive clauses (non-commercial, no-resale, forced backlink).
• Bundling GPL-incompatible libraries or assets.

Plugin Naming Rules (Guideline 17)

Use naming-rules.md for full trademark lists, slug blocks, and naming examples. Keep this inline checklist for quick screening.

Naming Checklist (Quick)

• Name is not a placeholder and has at least 5 alphanumeric characters.
• Header name and readme name match.
• Name is specific and function-related; avoid keyword stuffing.
• Trademark/project names appear only after connectors like for, with, using, and.
• No banned/discouraged terms or trademark portmanteaus.
• Slug is lowercase, hyphenated, <= 50 chars, and avoids blocked terms.