The best WordPress SEO plugin for AI features, compared
Hydrogen SEO (ours) is the pick for AI features: alongside AI writing help, it ships Hydrogen AI, an agent you brief in plain language ("write meta descriptions for every post missing one") that makes the change itself through the plugin's registered tools, shows every edit and asks before anything with no undo. As of our comparison, none of the other six offered plain-language agent delegation. Yoast, Rank Math, All in One SEO and SEOPress offer AI writing tools; The SEO Framework has none, by design.
We build Hydrogen SEO, and AI is where we built it to compete, so read this as a builder's ranking. We have not measured the quality of any plugin's AI output, ours included.
How we ranked them
AI features cannot be benchmarked the way PHP time can, so this ranks on documented capability, in three layers:
- Does it offer AI at all, and what do you need to use it?
- Does it work one field at a time, or handle bulk work across a site?
- Does it execute the work under a safety model, or only suggest text for you to paste?
For Hydrogen SEO we describe what its docs document; for the others, only what our comparison sources support. Positions 2 to 5 cannot be separated on capability from those sources, so we ordered them by measured block editor weight, since the editor is where AI writing tools live. Check each vendor's current pages.
Hydrogen SEO
+12.9 ms front-end, +1 queries, 0 custom tables, 10 JSON-LD types
Hydrogen AI runs in the dashboard (site-wide) and in the editor's SEO Settings sheet (scoped to one post). It drafts titles, descriptions and social copy, generates, expands or improves content, generates featured images, drafts schema, and takes bulk jobs across many posts. Separately, ◆ Generate Alt Text buttons in the Media Library write alt text for one image or a selection, at 1 credit each. It needs a free hydrogenseo.com account; when credits run out, only AI pauses. See meet Hydrogen AI.
SEOPress
+24.5 ms front-end, +1 queries, 1 custom tables, 0 JSON-LD types
Offers AI writing tools, per our comparison sources; we have not tested them. Its block editor is the lightest of the four plugins in this group at 217 KB.
Rank Math
+36.1 ms front-end, +16 queries, 6 custom tables, 6 JSON-LD types
Invested in AI early and offers AI writing tools inside a dense, highly configurable interface. We have not measured its AI layer. Its editor loads 1,792 KB of assets. See Hydrogen SEO vs Rank Math.
All in One SEO
+53.5 ms front-end, +22 queries, 9 custom tables, 8 JSON-LD types
Offers AI writing tools as part of a polished, guided product; we have not tested them. Its editor is heavy at 130 files and 3,543 KB, and it had the highest server cost in our benchmark.
Yoast SEO
+39 ms front-end, +3 queries, 6 custom tables, 12 JSON-LD types
Offers AI writing tools alongside its long-established content analysis; we have not tested them. It loads 4,160 KB of its own assets into the block editor, the heaviest figure we measured. See Yoast SEO alternatives.
Slim SEO
+10 ms front-end, +2 queries, 0 custom tables, 10 JSON-LD types
Our comparison sources do not cover AI features for Slim SEO, so we make no claim either way. Its appeal is almost nothing to configure and a 1.4 MB package.
The SEO Framework
+8 ms front-end, +0 queries, 0 custom tables, 9 JSON-LD types
No AI features, by design. Its philosophy is automation through sensible defaults rather than generated content, and it is the lightest plugin we measured. If you want no AI in your SEO plugin at all, that is a point in its favor.
How Hydrogen AI's safety model works
An agent that can edit your site needs hard limits. Hydrogen AI is gated three ways: the AI Abilities toggle must be on (when it is off, the tools are not registered at all), the abilities are locked to your domain, and only users with manage_options can drive it. It connects through one WordPress application password named "Hydrogen SEO Agent", which works only for REST requests and can be revoked from the plugin or from Users → Profile → Application Passwords.
Four approval policies set how much it asks: Ask before permanent changes (the default), Ask before every change, Run everything, and Dry run, which investigates and reports without changing anything. You can stop it mid-task. It works only through the plugin's SEO tools (metadata, schema, sitemaps, robots rules, redirects, alt text and featured images) and has no file, theme or plugin access. Full details: AI abilities and safety.
What AI will and won't do for your SEO
AI saves the most time on repetitive work: 200 posts missing descriptions, or a media library without alt text. It does not know your business better than you do, so review drafts, especially facts and opening hours in schema.
Hydrogen SEO's AI-visibility analysis for answer engines is coming soon, not available yet. What you can do today needs no AI: keep output in server-rendered HTML (all seven plugins do), publish an llms.txt file if you want to, and write pages that answer the question up front, as our guide to optimizing for AI Overviews explains.
All seven, measured
| Measured | Hydrogen SEO 0.0.18 | SEOPress 10.2 | Rank Math 1.0.278 | All in One SEO 5.0.1.1 | Yoast SEO 28.4 | Slim SEO 4.10.1 | The SEO Framework 5.1.4 |
|---|---|---|---|---|---|---|---|
| Front-end PHP time added | +12.9 ms | +24.5 ms | +36.1 ms | +53.5 ms | +39 ms | +10 ms | +8 ms |
| Peak memory added | +4.5 MB | +6.5 MB | +8.5 MB | +14.5 MB | +10.5 MB | +2 MB | +2 MB |
| Database queries added | +1 | +1 | +16 | +22 | +3 | +2 | +0 |
| Hooks registered | +22 | +114 | +155 | +100 | +187 | +51 | +8 |
<head> bytes added | +4,259 | +2,380 | +4,965 | +6,668 | +5,656 | +1,649 | +3,821 |
| Meta description by default | Yes | Yes | Yes | Yes | No | Yes | Yes |
| JSON-LD types printed | 10 | 0 | 6 | 8 | 12 | 10 | 9 |
| Open Graph / X tags | 10 / 5 | 10 / 6 | 11 / 8 | 6 / 3 | 10 / 5 | 11 / 2 | 10 / 5 |
| Sitemap URLs listed | 72 | 58 | 59 | 73 | 75 | 73 | 51 |
| Sitemap image entries | 40 | 40 | 0 | 0 | 40 | 40 | 0 |
lastmod coverage | 72 / 72 | 50 / 58 | 59 / 59 | 73 / 73 | 74 / 75 | 50 / 73 | 51 / 51 |
| Custom database tables | 0 | 1 | 6 | 9 | 6 | 0 | 0 |
| Autoloaded options added | +0.4 KB | +3.6 KB | +11.6 KB | +14.6 KB | +13.6 KB | -0.2 KB | +4.2 KB |
| Plugin package size | 4.6 MB | 11.7 MB | 15.1 MB | 24.4 MB | 21 MB | 1.4 MB | 2.9 MB |
| Block editor assets | 2 files, 700.4 KB | 17 files, 217 KB | 24 files, 1,792 KB | 130 files, 3,543 KB | 48 files, 4,160 KB | 14 files, 187.7 KB | 25 files, 77.6 KB |
| After deactivation | +0.2 KB left autoloading | No reduction at all | +11.0 KB still autoloading | No reduction: 14.5 KB still autoloading | +2.6 KB left autoloading, 6 tables remain | Releases everything | Releases everything (exact baseline) |
Measured on one WordPress 7.1 install (PHP 8.2, MySQL 8.0, Twenty Twenty-Five, 40 posts), each plugin alone with default settings, against a no-plugin baseline. Bold marks the better number in each row. Full method: how we tested.
Common questions
Which WordPress SEO plugin has the best AI features?
Hydrogen SEO, in our view as its builder: it adds a plain-language agent that makes changes through registered tools, on top of AI writing and alt text. Yoast, Rank Math, All in One SEO and SEOPress offer AI writing tools.
Do Hydrogen SEO's AI features cost money?
They need a free hydrogenseo.com account, which includes free credits. Each generation uses credits, alt text costs 1 credit per image, and paid plans cover heavier use.
Can Hydrogen AI change my site without asking?
Not by default. The default policy asks before anything with no undo, every change is shown to you, and you can switch to asking before every change or to a dry run.
What happens when AI credits run out?
Only AI generation pauses. Titles, schema, sitemaps, redirects and every other non-AI feature keep working, and nothing the AI already wrote is removed.