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CMB2

By Justin Sternberg

Developer Tools & Customization / Code Snippets & Custom Code

Reviewed by Omar Dabbas

Trusted WordPress expert with 20+ years of experience evaluating plugins for the WP ecosystem.

CMB2 Review - In-Depth Analysis

CMB2 is a powerful library for creating metaboxes, custom fields, and forms in WordPress. It simplifies meta management for posts, users, and more.

Performance Overview

WPS Score

7.15/10

User Rating

5/5 (based on 91+ reviews)

Active Installations

300,000+

Update Frequency

Below Average It is calculated using the weighted average of same category plugins.

Security Score

6.2 / 10 (Medium Risk) It is calculated using the weighted average of all versions.

What It Does

CMB2 is a developer's toolkit for building metaboxes, custom fields, and forms for WordPress that will blow your mind. Easily manage meta for posts, terms, users, comments, or create custom option pages.

CMB2 is a complete rewrite of Custom Metaboxes and Fields for WordPress. To get started, please follow the examples in the included example-functions.php file and have a look at the basic usage instructions.

You can see a list of available field types here. Development occurs on Github, and all contributions are welcome. Please read the CONTRIBUTING doc for more details.

Features include creating metaboxes for post edit screens, forms for options pages, user meta, and term meta. The flexible API allows you to use CMB forms almost anywhere, even on the front-end. There are numerous hooks and filters for customization, and repeatable fields are supported.

If you are looking to provide language translation files, please do so via WordPress Plugin Translations. CMB2 documentation can be found at the CMB2 wiki on GitHub.

Comparing to Alternatives

CMB2 competes in a crowded custom fields space alongside both free and premium frameworks. It stands out as a long-standing, developer-oriented option prized for its flexibility and clean API, though newer alternatives offer more modern UIs or bundled premium features.

Top alternatives

Strengths

Fully free with no upsells, unlike many competitors that gate advanced fields behind pro tiers
Well-documented API favored by developers for hooking and extending functionality
Large ecosystem of add-ons for integrations like FacetWP and post relationships
Proven stability from years of active development and maintenance

Weaknesses

Lacks a polished visual field builder compared to some modern alternatives
Has had at least one notable security vulnerability requiring an update
Steeper learning curve for non-developers compared to more UI-driven plugins

User Sentiment Analysis

With a 5/5 average across 91 ratings and 98.9% five-star reviews, user sentiment toward CMB2 is overwhelmingly positive. Only a single 1-star rating exists, and no accompanying negative review text was found to explain it, suggesting an isolated case rather than a widespread issue.

Positive highlights

"Easy to use, nice metaboxes for all post types" — ajanes94
"CMB2 gives you full and complete control, with API documented and dozens of add on plugins out there" — Ipstenu (Mika Epstein)
"Simple and free and much better than advance custom fields" — paknejad
"One of the best plugin for developers. Simple and effective" — suiramus
"Excellent plugin, I've always used it" — nunziorash

Common complaints

Weaknesses

A known high-severity PHP Object Injection vulnerability existed in versions before 2.11.0
No recent negative reviews exist to help identify emerging pain points
Reliance on developer familiarity may leave less technical users without guidance

Who Should Use This?

Best for

CMB2 is best suited for developers and agencies who want granular, code-level control over custom fields and metaboxes, and who value a mature, well-documented API with a rich add-on ecosystem.

Not ideal for

Users seeking a no-code, drag-and-drop field builder, or those wary of past security vulnerabilities, may prefer a more actively hardened or beginner-friendly alternative. Sites not kept updated could remain exposed to the historical PHP Object Injection flaw if running outdated versions.

Pricing & Value

Free version includes

CMB2 is entirely free and provides a comprehensive custom fields and metaboxes framework, including numerous field types, post type support, and hooks for deep customization, all without feature restrictions.

Final Verdict

CMB2 earns near-universal praise from its user base, with a perfect 5-star average and glowing feedback from developers who value its flexibility, documentation, and extensibility. Its fully free model, combined with a strong add-on ecosystem, makes it an appealing choice against both free and premium alternatives like Meta Box or ACF: Extended.

The one blemish is a past high-severity vulnerability, now patched in version 2.11.0, which underscores the importance of keeping the plugin updated. For developers comfortable managing updates and seeking a proven, code-friendly custom fields solution, CMB2 remains a strong, well-regarded choice.