For most WordPress sites, the best SEO plugin is Yoast SEO or Rank Math, and the gap between them is smaller than their marketing suggests. Both handle what search engines need from a plugin: titles and meta descriptions, XML sitemaps, schema, canonical tags and noindex controls. Choose Rank Math if you want a redirect manager and a 404 log without paying. Choose Yoast if you want the plugin most large WordPress sites already run. If a small footprint matters most, Slim SEO and The SEO Framework cover the essentials in a fraction of the code.
Some of the highest-ranking comparisons of these plugins are published by the plugin companies themselves, so we skipped the opinions and measured instead. On September 23, 2026 we checked which SEO plugin 1,149 WordPress sites from the world’s 20,000 most-visited domains actually run, downloaded the current version of six plugins to measure them and read their code, and took prices from each vendor’s own pricing page.
- Yoast SEO runs on 54.7% of the top-ranked WordPress sites we checked, three times as many as every other SEO plugin combined.
- Rank Math is a distant second at 11.1%. More than a quarter of the sites (27.4%) showed no SEO plugin at all.
- Updates lag badly: only 31.7% of Yoast sites ran the current release, and 18.1% ran a version more than a year old.
- On disk the plugins differ roughly 25-fold (Slim SEO is 0.9 MB unpacked, All in One SEO is 22.5 MB), but on the page each one adds only 3 to 5 KB of markup.
- Rank Math and Slim SEO include a redirect manager and a 404 log for free. Yoast, All in One SEO and SEOPress charge for them.
- Four of the six plugins now register abilities for AI agents, which the WordPress MCP Adapter can expose to tools like Claude and ChatGPT. Rank Math registers the most, with 29.
Which SEO plugin should you use?
Every plugin in this comparison covers the basics, so the decision comes down to which extras you want for free, how much code you are willing to run, and what you already use. Here is the short version.
| If you are… | Use | Why |
|---|---|---|
| Starting a new blog or small business site with no budget | Rank Math | Redirects, a 404 log, schema and importers are all in the free plugin. |
| Running a site a team or agency will maintain for years | Yoast SEO | It is what most large WordPress sites already run, so whoever maintains the site next will very likely know it. |
| Building a fast, developer-managed site | Slim SEO | The smallest plugin we measured, with automatic output and a free redirect manager. |
| Managing many client sites | SEOPress | SEOPress PRO covers unlimited sites for $149 a year and renews at the same price. |
| Already happy with one of these | Stay put | Switching between mainstream SEO plugins will not change your rankings on its own. |
Whichever you pick, install exactly one. If you are new to plugins, our guide to installing a WordPress plugin walks through it, and our WordPress SEO tips cover the settings worth changing once it is active.
What 1,149 top WordPress sites actually run
Our sample comes from the WordPress version study we ran earlier this month, which scanned the top 20,000 domains in the Tranco ranking and confirmed 1,203 of them run WordPress. We fetched each of those homepages again and looked for the fingerprint every major SEO plugin leaves in its HTML. Of the 1,203, 1,149 responded.
| SEO plugin | Sites | Share of all 1,149 sites | Share of sites with an SEO plugin |
|---|---|---|---|
| Yoast SEO | 628 | 54.7% | 75.3% |
| Rank Math | 127 | 11.1% | 15.2% |
| All in One SEO | 42 | 3.7% | 5.0% |
| The SEO Framework | 21 | 1.8% | 2.5% |
| SEOPress | 9 | 0.8% | 1.1% |
| SmartCrawl | 6 | 0.5% | 0.7% |
| Slim SEO | 3 | 0.3% | 0.4% |
| Squirrly SEO | 0 | 0% | 0% |
| No SEO plugin detected | 315 | 27.4% | n/a |
Yoast’s lead among big sites is even wider than its lead overall. WordPress.org counts more than 10 million active Yoast installs and more than 4 million for Rank Math, but in the top 20,000 Yoast outnumbers Rank Math almost five to one. Part of that is age. Yoast has been in the WordPress.org directory since 2010 and Rank Math since November 2018, and our read is that large organizations rarely swap out a plugin that touches every page of the site.
The 315 sites with no detectable SEO plugin are not necessarily ignoring SEO. That group can include sites that handle titles and meta tags in custom code or in their theme, and sites running a plugin with its credit comment switched off.
Two sites printed output from two different SEO plugins on the same page. Running two SEO plugins at once is a classic source of duplicate titles, meta descriptions and schema, which is why Yoast and SEOPress both warn you when they detect another SEO plugin running alongside them.
Paying customers are common at this level. Of the Yoast sites that print their edition, 41.9% run Yoast SEO Premium. At least 48.0% of the Rank Math sites run Rank Math PRO, and 18 of the 33 All in One SEO sites that print their edition run the paid version.
Most sites run an out-of-date SEO plugin
Yoast prints its version number in the source of every page, which makes it a useful gauge of how well sites keep plugins current. Yoast ships a new release every two weeks (28.4 on September 1 and 28.5 on September 15, for example), and 537 of the Yoast sites in our sample exposed their version.
| Yoast version on the site | Released | Sites | Share |
|---|---|---|---|
| 28.5 or newer (current) | September 15, 2026 or later | 170 | 31.7% |
| 28.0 to 28.4 | July 6 to September 1, 2026 | 174 | 32.4% |
| 26.0 to 27.9 | September 23, 2025 to June 22, 2026 | 96 | 17.9% |
| 25.9 or older | Before September 23, 2025 | 97 | 18.1% |
The median site was two releases, or about a month, behind. The long tail is the problem: almost one Yoast site in five runs a version more than a year old, and the oldest we found was Yoast SEO 3.8, a release from November 2016.
All in One SEO shows the same pattern from the other direction. Its current release line is 5.x, and 19 of the 33 sites that print a version have already moved to it.
An SEO plugin writes the head of every page on your site, so it is one of the last plugins you want to leave on an old version. WordPress has supported per-plugin automatic updates since version 5.5: on the Plugins screen, click “Enable auto-updates” next to your SEO plugin. If the update emails get noisy, you can turn off the auto-update notifications without turning off the updates.
How much each plugin weighs
SEO plugins have a reputation for bloat, so we downloaded the current free version of each from WordPress.org and measured it.
| Plugin | Version | Download | Unpacked | Files |
|---|---|---|---|---|
| Yoast SEO | 28.5 | 5.2 MB | 17.0 MB | 1,964 |
| Rank Math | 1.0.279 | 3.7 MB | 12.5 MB | 1,337 |
| All in One SEO | 5.0.1.1 | 7.6 MB | 22.5 MB | 1,284 |
| SEOPress | 10.2 | 2.8 MB | 8.9 MB | 1,334 |
| The SEO Framework | 5.1.4 | 0.75 MB | 2.3 MB | 333 |
| Slim SEO | 4.10.1 | 0.33 MB | 0.9 MB | 216 |
The spread is large, but disk size is not page speed. JavaScript makes up 35% to 60% of Yoast, Rank Math and All in One SEO by size, and most of it runs in the admin screens and the block editor, not on the pages your visitors load.
What visitors do download is the markup each plugin adds to the page head: the title, meta tags, social tags and schema. We measured that block on every homepage where the plugin printed both its opening and closing comment.
| Plugin | Median head markup | Middle half of sites | Homepages measured |
|---|---|---|---|
| The SEO Framework | 3.1 KB | 2.7 to 3.8 KB | 21 |
| Yoast SEO | 3.6 KB | 2.6 to 4.4 KB | 540 |
| All in One SEO | 4.1 KB | 3.2 to 4.5 KB | 33 |
| Rank Math | 4.9 KB | 3.4 to 6.0 KB | 82 |
The heaviest and lightest are less than 2 KB apart before compression. If your site feels slow, the SEO plugin is unlikely to be the reason, and our guide to speeding up WordPress covers the things that usually are.
What you get for free
All six plugins generate XML sitemaps and JSON-LD schema, so neither is a reason to choose one over another. The real differences are in the extras, and we checked these against each plugin’s free source code rather than its marketing pages.
| Plugin | Redirect manager | 404 log | llms.txt file | AI agent abilities |
|---|---|---|---|---|
| Yoast SEO | No (Premium) | No | Yes | 5 |
| Rank Math | Yes | Yes | Yes | 29 |
| All in One SEO | No (Pro plan) | No (Pro plan) | Yes | 13 |
| SEOPress | Per-post redirects only (full manager in PRO) | No (PRO) | No (PRO) | 8, off by default |
| The SEO Framework | Per-page 301 field only | No | No | None |
| Slim SEO | Yes | Yes | No | None |
Redirects matter more than they look. Every time you change a URL or delete a post, a redirect keeps the old link and its search traffic working. Yoast Premium prompts you to create one when you move or delete a page, but with the free plugin you need a separate redirect plugin or server rules.
The last column is new this year. WordPress 6.9 added the Abilities API, which lets plugins describe actions that software can call, and the official MCP Adapter exposes the abilities marked public to AI agents such as Claude and ChatGPT. Yoast, Rank Math and All in One SEO flag theirs for MCP, so an agent connected to your site can pull SEO data and, depending on the plugin, change titles, descriptions or site-wide settings. SEOPress exposes its eight only after you switch them on in its advanced settings. Our WordPress MCP guide covers how to connect an agent.
Yoast vs Rank Math
Most people end up choosing between these two, so here they are side by side.
| Yoast SEO | Rank Math | |
|---|---|---|
| Top-20,000 WordPress sites running it | 628 (54.7%) | 127 (11.1%) |
| Paid edition share | 41.9% run Premium | At least 48.0% run PRO |
| Active installs (WordPress.org) | 10+ million | 4+ million |
| Rating (WordPress.org) | 4.8 from 27,819 ratings | 4.8 from 7,506 ratings |
| Support issues resolved, last two months | 22 of 30 | 39 of 40 |
| Unpacked size | 17.0 MB | 12.5 MB |
| Median head markup | 3.6 KB | 4.9 KB |
| Free redirect manager and 404 log | No (redirects in Premium) | Yes |
| AI agent abilities | 5 | 29 |
| Cheapest paid plan | $118.80 a year, 1 site | $107.88 a year list price, unlimited personal sites |
Rank Math gives away more. The redirect manager and 404 log are in the free plugin, it registers 29 AI agent abilities to Yoast’s 5, and its PRO plan covers unlimited personal sites. Yoast’s advantages are reach and familiarity: it runs on almost five times as many top sites, it has nearly four times as many WordPress.org ratings, and whoever inherits your site next has almost certainly used it before.
Both are actively maintained. Yoast ships every two weeks, and Rank Math’s latest release landed the day before our check. WordPress.org’s support stats show 39 of 40 issues resolved in the last two months for Rank Math, against 22 of 30 for Yoast.
The lightweight picks: Slim SEO and The SEO Framework
If you want an SEO plugin that mostly stays out of the way, these two are built for it.
Slim SEO
Slim SEO is the smallest plugin we measured, 0.9 MB unpacked, or about a twentieth of Yoast. Its pitch is automation: it generates meta tags and schema with very few settings to configure, and it still includes a redirect manager and a 404 log for free. It can import from Yoast, Rank Math, All in One SEO, The SEO Framework, SEOPress and Squirrly. It is also the least used of the six in our sample (three sites), with 70,000+ active installs on WordPress.org, and Slim SEO Pro starts at $59 a year.
The SEO Framework
The SEO Framework has the smallest head output in our scan, a median of 3.1 KB, and the highest WordPress.org rating of the group at 4.9 stars. Two cautions. Its last release was 5.1.4 on December 10, 2025, and it is marked as tested only up to WordPress 6.9, two major versions behind the current 7.1. In the last two months, 3 of 10 support issues were marked resolved. None of that means it is broken on current WordPress, but it is worth watching before you build a new site on it. Migrating to it runs through the free Transport extension, which imports from Yoast, Rank Math and SEOPress.
Every plugin here is free on WordPress.org. These are the cheapest paid plans, taken from each vendor’s pricing page on September 23, 2026, in US dollars before tax.
| Plugin | Cheapest paid plan | Sites | Notes |
|---|---|---|---|
| Yoast SEO | Premium: $118.80 a year | 1 | Extra team seats cost $5 a month each. |
| Rank Math | PRO: $107.88 a year ($8.99 a month, billed annually) | Unlimited personal sites | That is the list and renewal price; it was discounted when we checked. |
| All in One SEO | Basic: $49.50 the first year | 1 | Renews at $99. The redirect manager needs the Pro plan ($199.50 the first year). |
| SEOPress | PRO: $49 a year | 1 | Renews at the same price. Unlimited sites cost $149 a year. |
| The SEO Framework | Pro: $84 a year ($7 a month, billed yearly) | 2 | The plugin itself stays free; paid plans add premium extensions and support. |
| Slim SEO | Slim SEO Pro Personal: $59 a year | 1 | Renews at the same price. Unlimited sites cost $179 a year. |
Switching SEO plugins
Each plugin stores your titles and descriptions in its own fields, so switching means importing that data, not just installing the new plugin. Most of them can import from the others.
| Switching to | Can import from |
|---|---|
| Yoast SEO | All in One SEO, Rank Math, The SEO Framework, Squirrly, SmartCrawl and several older plugins |
| Rank Math | Yoast SEO, All in One SEO, SEOPress |
| All in One SEO | Yoast SEO, Rank Math, SEOPress |
| SEOPress | Yoast SEO, All in One SEO, Rank Math, The SEO Framework, Slim SEO, Squirrly, SmartCrawl and others |
| The SEO Framework | Yoast SEO, Rank Math, SEOPress (through the free Transport extension) |
| Slim SEO | Yoast SEO, Rank Math, All in One SEO, The SEO Framework, SEOPress, Squirrly |
Before you switch, take a full backup of your site, and if you can, run the import on a staging site first. After the import, spot-check the titles and descriptions on a few posts, then deactivate the old plugin so the two never run together.
Do llms.txt files matter?
Yoast, Rank Math and All in One SEO can now generate an llms.txt file in their free versions, and SEOPress offers one in PRO. The file is often pitched as a way to show up in AI search, but Google’s own documentation for AI Overviews and AI Mode says “You don’t need to create new machine readable files, AI text files, or markup to appear in these features.” Treat it as optional, not as a reason to pick one plugin over another.
If what you really want to know is whether ChatGPT, Gemini, Perplexity and Claude mention your site, measure that directly. RightBlogger’s AI Brand Monitor runs real prompts on those assistants on a schedule and reports how often your site comes up (RightBlogger is another product I run).
How we measured
- Sites: the 1,203 WordPress sites our version study confirmed in the Tranco top 20,000. We fetched each homepage again on September 23, 2026, and 1,149 responded.
- Detection: each plugin’s own credit comment or schema identifier, taken from its current source code. Yoast, Rank Math and The SEO Framework let site owners switch the comment off, so every count is a minimum. SEOPress prints no credit comment at all; we could only detect it through a schema tag it adds to the homepage when that option is on, so it is the most undercounted.
- Plugin size: the current free package of each plugin from WordPress.org, measured zipped and unpacked.
- Head markup: the bytes between each plugin’s opening and closing comments on the homepage, before compression, measured only where both comments were present.
- Features and importers: read from each plugin’s free source code. Paid features and prices come from each vendor’s own pages.
- WordPress.org figures (installs, ratings, support issues, last update, tested-up-to version): the WordPress.org plugin API, the same day.
For transparency, SmartWP itself runs the free version of Yoast SEO.
Frequently asked questions
Which is better, Yoast or Rank Math?
Rank Math includes more in its free version, including a redirect manager, a 404 log and 29 abilities for AI agents. Yoast SEO is far more widely used: it runs on 54.7% of the top-ranked WordPress sites we checked, against 11.1% for Rank Math. Both handle titles, meta descriptions, sitemaps and schema equally well, so either is a sound choice.
What is the most popular WordPress SEO plugin?
Yoast SEO. WordPress.org lists it at more than 10 million active installs, and it runs on 54.7% of the WordPress sites in the Tranco top 20,000 that we checked in September 2026, more than every other SEO plugin combined.
Is there a free SEO plugin for WordPress?
Yes. Yoast SEO, Rank Math, All in One SEO, SEOPress, The SEO Framework and Slim SEO all have free versions on WordPress.org. Rank Math and Slim SEO include the most in their free versions, including a redirect manager and a 404 log.
Is Rank Math free or pro?
Both. The Rank Math plugin on WordPress.org is free. Rank Math PRO adds more features and support, and lists at $8.99 a month billed annually ($107.88 a year) for unlimited personal websites.
Can I use two SEO plugins at the same time?
You should not. Two SEO plugins will both print titles, meta descriptions and schema, which creates duplicates. Import your data into one plugin and deactivate the other. Two of the 1,149 sites we checked were running two SEO plugins at once.
Does an SEO plugin slow down WordPress?
Not noticeably. On the live homepages we measured, the plugins added a median of 3.1 KB to 4.9 KB of HTML to the page head. Most of a large plugin download is admin and editor code that visitors never load.
Do I need an SEO plugin at all?
Not strictly. WordPress itself outputs canonical links on single posts and pages and has generated an XML sitemap at /wp-sitemap.xml since version 5.5. What core lacks is a way to write meta descriptions, set social sharing images, or noindex individual pages without code, and that is what most people install an SEO plugin for.
How can I tell which SEO plugin a site uses?
View the page source and search for the plugin’s comment. Yoast prints “This site is optimized with the Yoast SEO plugin”, Rank Math prints “Search Engine Optimization by Rank Math”, All in One SEO prints “All in One SEO” followed by its version number, and The SEO Framework prints its own name. Site owners can switch these comments off, so no comment does not always mean no plugin.
