On July 14, 2026, the block plugin used by more than a million WordPress sites, Spectra, changed its name. It became Spectra Legacy, will get no new features, and its successor, Spectra Blocks, started from zero installs. Pages built with the old plugin do not migrate on their own: that is a deliberate choice by the vendor.
That story sums up what is at stake with a block library. These plugins extend WordPress’s native editor, without a page builder, with columns, tabs, counters or forms. But every one of their blocks becomes a dependency of your content. The day the plugin goes away, or changes generation, your pages carry the mark.
This comparison judges ten block libraries on what matters in the long run: what remains of your pages if you remove the plugin, how it loads its CSS, how well it aligns with WordPress’s native tools and its maintenance status in October 2026.
How we ranked them
We read the plugins’ code rather than their marketing, except for Getwid, judged on its listing and changelog. The first criterion is what survives a deactivation, determined by how each block saves its content. The second is CSS loading: one file per block used, or a global stylesheet loaded as soon as any block appears.
Then come the use of the editor’s native settings, which let the theme drive the blocks, the date of the last update, and the number of genuinely useful blocks, once you remove those WordPress now provides itself. To decide whether you need a page builder rather than a block library, read our comparison of Gutenberg and page builders.
The file sizes quoted below are those of the files shipped in each plugin, not speed measurements we ran ourselves.
What remains of your pages when you remove a block plugin
Static blocks, dynamic blocks
A static block saves its HTML in the database. A dynamic block only stores a comment and its settings, and its HTML is produced at display time by the plugin’s PHP code. The Block Editor Handbook is clear: without the plugin, WordPress displays the saved HTML, if any exists. Your content never disappears from the database, but how it renders can change completely.
CSS, the first casualty
Most libraries save HTML but generate the CSS at display time, from the block’s settings. Deactivate the plugin, and the text stays, but with no colors, no spacing and no layout. Only one library in this comparison, Stackable, saves its blocks’ CSS inside the content itself, which preserves a good part of the look.
Layouts built in PHP
The riskiest case concerns layout blocks whose wrapper only exists at display time. Kadence Blocks’ row block, for example, only saves its inner content: the wrapper that places the columns side by side is built by the plugin’s code. Without it, that wrapper disappears, the columns lose their layout and the content stacks up. In the editor, an orphaned block shows a notice offering to keep it as is, convert it to custom HTML when it saved some, or remove it.
Check before deactivating
Before removing a library, count the content that uses it, on a working copy. This read-only query, here for Kadence, counts the affected posts by type:
wp db query "SELECT post_type, COUNT(*) FROM $(wp db prefix)posts WHERE post_content LIKE '%wp:kadence/%' AND post_type NOT IN ('revision') GROUP BY post_type;"Do not forget templates, template parts, synced patterns and navigation menus, which block themes also store as posts. Our selection of essential WP-CLI commands covers these tools.
1. GenerateBlocks: few blocks, clean HTML
What it does
GenerateBlocks, from EDGE22 Studios, the company behind the GeneratePress theme, offers a handful of generic blocks: a container or grid element, text, media, shapes and a query loop. Its philosophy fits in one idea: learn a few blocks deeply and build anything with them. It runs on more than 200,000 sites.
Strengths
It produces simple HTML and generates one CSS file per page, limited to the blocks used. Google Fonts are disabled by default. For a developer, it is the cleanest base in this comparison.
Limits
There is no ready-made testimonial or countdown block: everything is built. Version 2, released in 2025, rewrote every block, and the old ones coexist on sites that used them. Its mobile and tablet breakpoints also differ from those WordPress 7.1 now offers.
Price and audience
GenerateBlocks Pro costs $99 per year, usable on 500 sites. It suits developers and agencies that want lean markup.
2. Kadence Blocks: the most complete toolkit, under the Liquid Web brand
What it does
Kadence Blocks, with more than 600,000 installs, offers a wide range: rows and columns, advanced text, forms, tabs, accordions, galleries, header and navigation builders. Since 2026, the StellarWP brand has disappeared, and Kadence is sold by Liquid Web, with Nexcess shown as the author on WordPress.org.
Strengths
Its intelligent loading only loads CSS and JavaScript for the blocks used on the page. A free performance module adds lazy loading of background images. Plenty of patterns and templates are available. Our comparison of WordPress page builders positions Kadence against heavier tools.
Limits
It is the library that creates the strongest dependency: its layout blocks build their wrapper in PHP, and the header, navigation and forms store their configuration in separate posts. Patchstack lists about forty fixed flaws in its history, mostly moderate, but including a critical flaw exploitable without an account, fixed in 2023, and three security releases came out in September 2026.
Price and audience
There is no longer a separate price for Kadence Blocks Pro: Kadence plans cost $99, $299 or $499 per year. Kadence Blocks suits sites already on the Kadence theme and those that want many ready-made blocks.
3. Spectra: one plugin became two
What it does
Spectra, from Brainstorm Force, the company behind the Astra theme, has existed in two forms since July 2026. Spectra Legacy, with more than a million installs, only receives security and compatibility fixes. Spectra Blocks, with more than 50,000 installs, is a complete rebuild on the editor’s modern interfaces, with fewer blocks by design.
Strengths
Spectra Blocks is the only library in this comparison whose blocks mostly declare the editor’s native settings: colors, spacing, typography, borders. The theme can therefore drive them, and since September 2026 its per-screen settings follow WordPress’s breakpoints. Each page only loads the CSS of its blocks.
Limits
You have to reason with two plugins, with no migration tool from one to the other. The vendor warns that custom CSS written for Legacy classes has to be redone. Spectra Blocks requires PHP 8.1, and its AI features go through a separate plugin, Zip AI, and a ZipWP account that runs on credits.
Price and audience
Spectra Pro costs $69 per year for three sites, and one license covers both plugins. Spectra suits Astra users; for a new site, start with Spectra Blocks.
The real case: Spectra, from one plugin to two, with a security flaw in between
Spectra’s story between late 2025 and autumn 2026 alone illustrates everything described here: deliberate content dependency, constant adaptation to WordPress releases, and security. Each step is documented by the vendor, by the plugin’s code and by vulnerability databases.
The warning
On November 14, 2025, the Spectra team announced a version 3 rebuilt from scratch, whose blocks would run separately from the old ones. It ruled out any automatic migration, which it said could break existing layouts, and promised the old blocks would keep working.
A flaw born from an adaptation
On December 4, 2025, version 2.19.17 added compatibility with WordPress 6.9, which now lets users hide a block. To do so, the plugin registered on the server any block named uagb/ found in the content, using the attributes written in the page as the block type’s registration arguments. That line of code opened a door: a contributor account could get code executed on the server, with content combining two fake blocks.
On May 4, 2026, version 2.19.26 fixed the flaw, reported by Wordfence, by emptying exactly those arguments. The US vulnerability database published CVE-2026-7465 on May 30, with the 8.8 out of 10 score assigned by Wordfence. Patchstack shows it as exploited, but it is not in the official catalog of exploited vulnerabilities kept by the US agency CISA: no exploitation has been publicly confirmed.
The side effects
In spring 2026, to keep up with WordPress 7.0 and its iframed editor, Spectra migrated all its blocks to version 3 of the block interface. The following releases fixed FAQ blocks flagged as invalid in the editor, then the Info Box block’s anchor, CSS classes and responsive conditions, which had vanished on the front end.
The split
On July 8, 2026, Spectra Blocks was accepted on WordPress.org, and its version 1.0.0 shipped on July 13. On July 14, the old plugin became Spectra Legacy, with the assurance that blocks, settings and content remained intact. At the end of July, the vendor explained its choice: rebuilding inside the old plugin would have exposed every existing site to a complete rewrite. Migration is optional, at your own pace.
In autumn 2026, Legacy keeps receiving security fixes and WordPress 7.1 compatibility, while Spectra Blocks has passed 50,000 installs, against more than a million for Legacy.
What to take away
A block library is a dependency of the content, not just of the editor: the vendor itself says a block needs its plugin to display and stay editable. A library can split into generations, and the old content does not follow by itself, as GenerateBlocks and Stackable showed before Spectra, both still shipping their first-generation blocks for old content. Finally, every WordPress release forces libraries to adapt, and that adaptation code is where bugs and flaws appear.
4. Stackable: CSS saved in the content
What it does
Stackable, with more than 100,000 installs, offers about forty blocks, a global design system, presets taken from the theme.json file and customizable breakpoints. Its pattern library is well stocked.
Strengths
It is the library that best survives a deactivation: each block saves its own CSS in the page content. Without the plugin, those styles remain; only the base layout stylesheet disappears. It can also inherit a block theme’s styles.
Limits
The vendor advertises a weight of a few kilobytes, but the stylesheet shipped in the current version weighs more than 90 KB uncompressed, loaded in one go, together with a small 13 KB responsive stylesheet, as soon as a Stackable block appears on the page. Old version 2 blocks are still shipped for content that uses them.
Price and audience
The Premium plan costs $49 per year for one site, and premium features keep working after expiry. Stackable suits designers who want a design system on top of a block theme.
5. Otter Blocks: display conditions and forms
What it does
Otter Blocks, from Themeisle, with more than 300,000 installs, adds about thirty blocks, display conditions, custom CSS and animations applicable to any block, and a form block with Stripe payments. Since July 2026, an AI toolbar relies on WordPress 7.0’s AI connectors.
Strengths and limits
Display conditions and forms often save installing two more plugins. CSS is generated in one file per post. Without the plugin, most blocks keep their HTML, without styles, and about a dozen dynamic blocks disappear. Two purchase verification bypass flaws were fixed in 2026.
Price and audience
Plans cost $69 per year for one site, $99 for five and $149 unlimited, at the price displayed in October 2026. Otter suits users of the Neve themes and sites that want conditions and forms in one tool.
6. Greenshift: animations, with a free core
What it does
Greenshift, with more than 70,000 installs, targets animated landing pages: a universal element block, CSS grid, advanced animations in a paid add-on. Its vendor says all core features are and will remain free.
Strengths and limits
Styles are split per block and only loaded when used, and since WordPress 7.1 the plugin applies the breakpoints declared in the theme. On the other hand, each block’s CSS lives in its settings: without the plugin, the styling disappears. Its listing claims testing with WordPress 7.2, a version not yet released, and its promise of a perfect mobile score is marketing.
Price and audience
The core is free; paid add-ons start at $39.99 per year, at the price displayed in October 2026. Greenshift suits animation-heavy pages, for users comfortable with a CSS class workflow.
7. Essential Blocks: the widest catalog
What it does
Essential Blocks, from WPDeveloper, with more than 200,000 installs, ships nearly sixty blocks in its free version, not counting child blocks, including WooCommerce product blocks, and lets you turn each block on or off individually.
Strengths and limits
The catalog is the richest in this comparison, and turning off unused blocks limits the weight. CSS is rebuilt at display time from the settings: without the plugin, the HTML stays but loses its styles. Its security record includes two serious flaws in 2023, exploitable without an account, and a WooCommerce sales data leak fixed at the end of July 2026 (version 6.4.0) and disclosed in August.
Price and audience
The Pro plan starts at $39 per year for one site, at the price displayed in October 2026. Essential Blocks suits sites that want many ready-made widgets, stores included.
8. Ultimate Blocks: editorial blocks and schema markup
What it does
Ultimate Blocks, with more than 50,000 installs, stands out with its editorial blocks: table of contents, review and how-to blocks with schema markup, expandable content, content filter.
Strengths and limits
For a blog or a review site, its blocks cover specific needs WordPress does not handle natively. But a single stylesheet of about 80 KB loads as soon as one of its blocks appears, and the advanced heading block calls Google Fonts from Google’s servers, a point to check under GDPR. Several blocks, such as the styled box, build their wrapper in PHP and lose it without the plugin.
Price and audience
Ultimate Blocks Pro starts at $39 per year for one site, at the price displayed in October 2026. Ultimate Blocks suits bloggers and review or affiliate sites.
9. Getwid: forty blocks moved to the native interface
What it does
Getwid, from MotoPress, with more than 50,000 installs, offers more than forty blocks and more than 35 ready-made templates. It now requires WordPress 7.0.
Strengths and limits
Its version 3.0, at the end of August 2026, modernized every block to use the latest block interface and native asset loading. It describes itself as compatible with block themes. The WordPress.org listing mentions no paid version.
Price and audience
Free on WordPress.org. Getwid suits sites that want a large collection of free blocks, recently brought up to date.
10. CoBlocks: still installed, not updated since March 2026
What it does
CoBlocks, from GoDaddy, with more than 300,000 installs, offers galleries, forms, pricing tables, restaurant menus and events, for free.
Deal-breaking limits
Its last release dates from March 2026, and it is only tested up to WordPress 6.8, three major versions behind. Its combined stylesheet weighs more than 250 KB uncompressed and loads on any page that displays a CoBlocks block. Its loading check, which also triggers on native blocks such as paragraphs, adds two small stylesheets of about 23 KB on almost every page. Such weight hurts Core Web Vitals.
Price and audience
Free. CoBlocks only suits existing sites that already use it, until it is replaced; it is not a choice for a new site.
What WordPress now does without a plugin
Part of what block libraries used to sell has arrived in core. WordPress 6.9, in December 2025, added an Accordion block and the ability to hide a block, which is then removed from the published HTML. WordPress 7.0 added Icon and Breadcrumbs blocks, and the choice of which blocks to show depending on screen size. WordPress 7.1 added a Tabs block, per-screen styles for every block that uses the native settings, and configurable breakpoints.
One important nuance: a block hidden on mobile with the WordPress 7.0 feature stays in the page, simply hidden by CSS, so the page is no lighter. Our article on what changed in WordPress 7 covers these features. Before installing a library, check that core does not already do what you need.
How to choose
- An existing site: keep the library in place, keep it updated, and only replace it when rebuilding the pages involved.
- A new site on a block theme: Spectra Blocks, aligned with the native settings, or GenerateBlocks for lean markup, with its own styling controls.
- A need for many widgets: Kadence Blocks or Essential Blocks, accepting the dependency.
- An editorial blog: Ultimate Blocks for the table of contents and reviews.
- Heavily animated pages: Greenshift.
Also think about who publishes. Most block library flaws require a contributor account or higher: limiting those accounts reduces the risk, as our guide to WordPress user roles explains. And do not stack two libraries that do the same thing.
Summary table
| Plugin | Installs | CSS loading | Without the plugin | Price (Oct. 2026) |
|---|---|---|---|---|
| GenerateBlocks | 200,000+ | File per page | HTML kept, no styles | Pro $99 per year |
| Kadence Blocks | 600,000+ | Per block used | Layouts lost | Kadence plans from $99 per year |
| Spectra Blocks | 50,000+ | Per block, native | Plugin required | Pro $69 per year, 3 sites |
| Stackable | 100,000+ | Global file when used | Styles partly kept | Premium $49 per year |
| Otter Blocks | 300,000+ | File per post | HTML kept, no styles | From $69 per year |
| Greenshift | 70,000+ | Per block, inline | HTML kept, no styles | Free, add-ons from $39.99 |
| Essential Blocks | 200,000+ | Rebuilt at display | HTML kept, no styles | Pro from $39 per year |
| Ultimate Blocks | 50,000+ | Global file when used | Some wrappers lost | Pro $39 per year |
| Getwid | 50,000+ | Native since 3.0 | Not checked | Free |
| CoBlocks | 300,000+ | Global file when used, small files almost everywhere | HTML kept, no styles | Free |
Frequently asked questions
Does my content disappear if I deactivate the plugin?
No, it stays in the database. What is lost is the rendering: the styles generated by the plugin, dynamic blocks and layouts built in PHP. Pages usually remain readable but often unrecognizable. The exception is a fully dynamic block that keeps its text in its settings, such as Spectra Blocks’ Text block: it displays nothing at all. Reactivate the plugin and everything comes back.
Can I use two libraries at once?
Technically yes, but each library adds its CSS, its scripts and its dependency. Pick one and stick with it, unless there is a specific need it does not cover.
Should I migrate from Spectra Legacy to Spectra Blocks?
There is no rush: Legacy still receives its security fixes. Use Spectra Blocks for new pages and rebuild the old ones during redesigns, since no tool converts them.
Are native blocks enough in 2026?
For many sites, yes: accordion, tabs, icons, breadcrumbs and per-screen styles are now in WordPress. A library remains useful for forms, counters, animations or editorial blocks with schema markup.
Who owns Kadence today?
The Liquid Web group, which already owned it through StellarWP. Since that brand disappeared in 2026, Kadence has been sold under the Liquid Web name, with Nexcess shown as the author on WordPress.org. The free plugin remains available on WordPress.org.
Verdict
A block library becomes a dependency of your content, for the whole life of the site. The best ones limit that dependency, by saving clean HTML, loading only the CSS needed and relying on WordPress’s native settings. GenerateBlocks saves the leanest HTML and loads only the CSS needed, with its own styling controls.
Spectra Blocks goes furthest in using the native settings, but several of its blocks, including Text and Button, save no HTML at all: without the plugin, their content is no longer displayed. Stackable best preserves the look, and Kadence offers the most at the cost of a strong dependency.
Spectra’s story is a final reminder that generations pass and old content does not follow by itself. Choose few, choose maintained, and check with every new WordPress release whether core already does what you are paying for.
Sources
- WordPress.org (October 2026). Spectra Legacy
- WordPress.org (October 2026). Spectra Blocks
- Team Spectra (July 31, 2026). Spectra Legacy and Spectra Blocks: Everything You Need to Know
- Team Spectra (November 14, 2025). Spectra V3 Beta
- NVD (May 30, 2026). CVE-2026-7465
- Patchstack (June 2, 2026). Spectra <= 2.19.25, Contributor+ Remote Code Execution
- WordPress Block Editor Handbook. Static or Dynamic rendering of a block
- Make WordPress Core, Aki Hamano (December 1, 2025). Ability to Hide Blocks in WordPress 6.9
- Make WordPress Core (March 15, 2026). Block Visibility in WordPress 7.0
- Make WordPress Core, Isabel Brison (August 5, 2026). Responsive block styles and configurable viewports in WordPress 7.1
- Make WordPress Core, Aki Hamano (August 3, 2026). Iframed Editor Changes in WordPress 7.1
- WordPress.org. WordPress 7.0 release page
- Make WordPress Core (November 25, 2025). WordPress 6.9 Field Guide
- Search Engine Journal, Roger Montti (May 13, 2026). Liquid Web WordPress Plugin Rebrand Triggers Backlash
- Liquid Web (October 2026). Kadence plans and pricing
- Liquid Web (October 2026). Kadence Blocks
- GitHub, Kadence Blocks. Row Layout save.js
- Brainstorm Force (October 2026). Spectra pricing
- EDGE22 Studios (October 2026). GeneratePress and GenerateBlocks pricing
- Gambit (October 2026). Stackable Premium
- GitHub, Stackable. Heading save.js
- Themeisle (October 2026). Otter Blocks pricing
- Wpsoul (October 2026). Greenshift pricing
- WordPress.org. Essential Blocks
- WordPress.org. Ultimate Blocks
- WordPress.org. Getwid
- WordPress.org. CoBlocks
- WordPress.org SVN. Spectra 2.19.26, class-uagb-init-blocks.php
- CISA. Known Exploited Vulnerabilities Catalog
- WordPress.org. GenerateBlocks
- WordPress.org. Kadence Blocks
- WordPress.org. Stackable
- WordPress.org. Otter Blocks
- WordPress.org. Greenshift
- Patchstack. Kadence Blocks vulnerabilities
- Patchstack. Essential Blocks vulnerabilities
- Patchstack. Otter Blocks vulnerabilities
- Ultimate Blocks (October 2026). Pricing
- WPDeveloper (October 2026). Essential Blocks
- WordPress.org. WordPress 7.1
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