About this plugin
Hydrogen SEO is a lightweight, AI-powered SEO plugin for WordPress. It writes your meta titles and meta descriptions, generates schema markup, fills in image alt text, and audits your site for the on-page issues that hold rankings back — all from a fast, modern dashboard and directly inside the block editor. It is built for how search works now. Alongside the metadata and structured data Google reads, it gives you an llms.txt editor and clean, machine-readable output, so the systems that answer questions from web content have something unambiguous to work from. Hydrogen AI: an SEO agent inside your dashboard Ask for what you want in plain language — “write meta descriptions for every post missing one”, “add FAQ schema to this page”, “find and fix broken internal links” — and Hydrogen AI does the work through the plugin’s own tools. It asks before anything it cannot undo, shows you every change it makes, and you can stop it at any point. Hydrogen AI lives in two places: the plugin dashboard for site-wide work, and a tab in the editor’s SEO Settings sheet scoped to the post you are editing. AI writing tools AI meta titles and meta descriptions — click the AI button beside the field, get several suggestions with character counts, pick one and it fills the field AI social titles and descriptions for Facebook / Open Graph and X (Twitter) AI image alt text for a single image or in bulk across your media library AI content generation and rewriting for SEO AI featured image generation AI-assisted schema (structured data) for your business details On-page SEO essentials SEO titles and meta descriptions with template variables for posts, pages, custom post types, taxonomies and archives Schema markup (JSON-LD): Article, Product, FAQ, HowTo, Recipe, Course, Event, Local Business, Breadcrumbs and more XML sitemaps Robots meta controls per post, plus a built-in robots.txt editor Open Graph and X (Twitter) card previews, so you see the share card before you publish Google search result (SERP) preview as you type Redirection manager with 301 and 302 support Homepage SEO settings and canonical URLs Built for AI search (AEO) llms.txt editor — publish crawl and usage guidance for large language models, the emerging standard for AI answer engines Structured data and metadata written to be machine-readable, so your pages are unambiguous to anything parsing them Server-rendered output — nothing about your SEO depends on JavaScript running Site audits and health checks The dashboard scores your site across seven areas — crawlability, performance, mobile, security, content structure, schema markup and technical health — with a clear list of what to fix first. Site-wide audits find duplicate titles and descriptions, keyword cannibalisation, orphan pages, broken internal links and metadata that is too long or too short. Fast and clean Modern React dashboard Heavy assets load on demand, so wp-admin stays quick No front-end JavaScript and no extra front-end requests — the SEO output is server-rendered markup Every screen is backed by the plugin’s own REST API Free account for AI features The AI features are powered by the Hydrogen SEO API. Create a free account at hydrogenseo.com , connect it from the plugin in one click, and you get free AI credits to start with. Every non-AI SEO feature — titles, meta descriptions, schema, sitemaps, robots.txt, redirections, previews, audits — works with no account and no key. Privacy Hydrogen SEO adds no tracking, no analytics, no cookies and no front-end scripts. It does not phone home on a schedule. Nothing leaves your site until you use a feature that needs the Hydrogen SEO API. Stored on your own site Your Hydrogen SEO API key, in the WordPress options table Your SEO settings, schema data, redirects and per-post metadata, in your own database The agent connection details when Hydrogen AI is connected: the service URL, a site identifier and a service key Nothing else. No visitor data, no personal data about your readers Sent to the Hydrogen SEO API, only on your action The text or image you ask an AI feature to work with — a topic, the content to improve, an image URL for alt text, a prompt for image generation, or your business details for schema Your API key, to authorise and meter the request For Hydrogen AI: your instructions, plus the SEO data of the pages it is working on When you connect an account: your site URL, and the name and email you choose to give When you connect Hydrogen AI: your site URL, your WordPress username, the application password described above, your WordPress version, the plugin version and the environment type (production, staging or local) Application password handling The application password the plugin mints for Hydrogen AI is transmitted over HTTPS and stored encrypted at rest (AES-256-GCM) by the Hydrogen SEO service, alongside a non-reversible fingerprint that only lets the interface confirm which credential is on file. Plain HTTP is refused for anything but local development hosts. If registration fails, the credential just created is deleted immediately rather than left on your account. Disconnecting, or revoking it in Users → Profile, ends that access. The setup wizard The wizard optionally asks for your name and email. If you fill them in and tick the consent checkbox, they are sent with your site URL so we can send you setup help and product updates. Both fields are optional, the wizard can be skipped, and nothing is sent if you leave them blank or do not consent. AI processing Generation is performed by the Hydrogen SEO API using AI model providers acting on its behalf, so the content of a request reaches those providers as part of producing your result. What is retained, and for how long, is set out in the privacy policy below. Privacy policy: https://hydrogenseo.com/privacy Terms of service: https://hydrogenseo.com/terms External services This plugin relies on the following third-party/external service. It is described here so you know what data is sent, when, and under which conditions. Hydrogen SEO API The plugin connects to the Hydrogen SEO API (hydrogenseo.com) for two things: 1. AI generation. Content generation and rewriting, metadata (SEO title and description) generation, image alt-text generation, AI image generation for featured images, and business/local schema generation. Data is sent only when you actively use an AI feature. Depending on the feature the request includes the text or image you ask it to work with — a topic, the content to improve, an image URL for alt text, a prompt for image generation, or your business details for schema — together with your configured API key. When you connect your account, your site URL and the name and email you choose to provide are sent so an API key can be issued. The plugin does not send this data in the background or without a user action. 2. Hydrogen AI (the agent). When, and only when, you switch on AI Abilities and connect the agent, the plugin registers your site with the service. That registration sends your site URL, your WordPress username, a freshly created WordPress application password named “Hydrogen SEO Agent”, your WordPress version, the plugin version and your environment type, authenticated with your API key. The service verifies the credential by calling back into your site before storing it, keeps it encrypted (AES-256-GCM), and uses it to read and change SEO data on your behalf while you use the agent. Your instructions and the SEO data of the pages being worked on are sent as part of each conversation. Agent access is gated three ways on your side: AI Abilities must be switched on, the abilities are locked to the domain they were enabled on, and only users with the manage_options capability can drive them. Disconnecting deletes the application password from your site; you can also revoke it from Users → Profile → Application Passwords at any time. This service is provided by Hydrogen SEO. Terms of service: https://hydrogenseo.com/terms — Privacy policy: https://hydrogenseo.com/privacy