redpen

<a href="http://redpen.cc" rel="nofollow ugc">RedPen</a> is a proofreading tool to help writers or programmers who write technical documents or manuals that need to adhere to a writing standard. This plugin integrates text validation provided by <a href="http://redpen.cc/docs/latest/index.html#server" rel="nofollow ugc">RedPen Server</a> into the WordPress editor.
<h3>Features</h3>
<ul>
<li>Validates text with RedPen as you type</li>
<li>Supports both Visual and Text WordPress editors</li>
<li>Validation errors are marked in Visual editor in-place</li>
<li>Validation error messages are also listed below and highlighted in the editor on click</li>
<li>Autodetection of supported languages and variants (currently, English or Japanese)</li>
<li>RedPen <a href="http://redpen.cc/docs/latest/index.html#validator" rel="nofollow ugc">validators</a> and <a href="http://redpen.cc/docs/latest/index.html#setting-symbols" rel="nofollow ugc">symbols</a> 
can be configured directly in WordPress panel below the editor</li>
<li>Configuration is stored for next visit with the same browser</li>
</ul>

RedPen WordPress plugin

This plugin integrates RedPen text validation into the WordPress editor.

Freemius

Cary Molyneux

Spellmatic scans your entire WordPress site for spelling and grammar errors, then lets you fix them in one click — including content built with Elementor, Avada, Divi, WPBakery, and more.
Most grammar tools only check what you’re currently editing. Spellmatic scans every post, page, product, and comment on your site — even content stored inside page builder data structures.
<h4>Features</h4>
<ul>
<li>Full-site scan across all posts and pages — no error cap</li>
<li>Privacy-first local grammar engine powered by Harper WASM — no data ever leaves your server</li>
<li>All errors shown per scan with fix / dismiss actions</li>
<li>Error dashboard with error type badges and in-context display</li>
<li>Custom dictionary — add words to ignore globally</li>
<li>Scheduled email digests with scan summaries</li>
<li>BYOK AI integration with OpenAI — contextual AI proofreading using your own API key</li>
</ul>
<h4>Premium Features</h4>
Premium plans add powerful extras for professionals and agencies. Available at <a href="https://spellmatic.com" rel="nofollow ugc">spellmatic.com</a>.
<ul>
<li>Bulk auto-fix — fix all errors across your site in one click</li>
<li>Smart fix — AI-powered contextual corrections</li>
<li>Additional AI providers — Claude, Gemini, Grok, and OpenRouter</li>
<li>Priority support</li>
</ul>
Pro ($79/year) 
* All premium features 
* Dedicated account management
Agency ($149/year) 
* Everything in Pro 
* Up to 10 WordPress sites / multisite network support
<h4>Page Builder Compatibility</h4>
Spellmatic scans content inside: 
* Elementor — reads JSON widget data (<code>_elementor_data</code>) 
* Avada / Fusion Builder — parses Fusion shortcodes and page options 
* Divi Builder — strips and scans Divi shortcode content 
* WPBakery Page Builder — scans all WPBakery shortcode text 
* Beaver Builder — reads serialized layout data 
* Bricks Builder — parses JSON element data 
* Oxygen Builder — reads builder meta 
* Brizy — reads JSON layout data 
* Gutenberg / Block Editor — native support 
* Kadence Blocks — native block support
<h4>Privacy First</h4>
The free tier uses Harper WASM — a blazing-fast, privacy-respecting grammar engine that runs entirely in your browser (client-side WebAssembly). Zero external API calls. Zero data sent anywhere. Your content stays yours.
The optional BYOK AI layer uses your own API key. Your key is stored encrypted on your server and all API calls go directly from your server to your chosen AI provider — Spellmatic never sees your content or your key.
<h3>External Services</h3>
This plugin connects to the following third-party services. Full details are also available on the Open Source & Services page inside the plugin (Spellmatic → Open Source).
<h4>Grammar Engine — Harper (Bundled)</h4>
The Harper grammar engine (Apache 2.0 licensed) is bundled with the plugin and runs entirely in your browser. No external connections are made during scanning.
You may optionally update the grammar engine to get improved dictionaries and grammar rules. No external connections are made by the plugin for grammar engine updates — all updates are performed manually by the site administrator:
<ol>
<li>Download the latest <code>harper.js</code> from the Harper npm package at <a href="https://www.npmjs.com/package/harper.js" rel="nofollow ugc">https://www.npmjs.com/package/harper.js</a> — the file is located in the <code>dist/</code> folder of the package.</li>
<li>Upload the file to <code>wp-content/uploads/spellmatic/harper.js</code> on your server (create the <code>spellmatic</code> folder if it does not exist).</li>
<li>The plugin will automatically detect and use the uploaded file on the next page load.</li>
<li>To revert, simply delete the file from <code>wp-content/uploads/spellmatic/</code> — the plugin will fall back to the bundled version.</li>
</ol>
<ul>
<li>Harper project: <a href="https://github.com/Automattic/harper" rel="nofollow ugc">https://github.com/Automattic/harper</a></li>
<li>Harper license: <a href="https://github.com/Automattic/harper/blob/master/LICENSE" rel="nofollow ugc">Apache License 2.0</a></li>
<li>Harper website: <a href="https://writewithharper.com" rel="nofollow ugc">https://writewithharper.com</a></li>
</ul>
<h4>AI-Powered Grammar Analysis (Optional, BYOK)</h4>
When you enable the BYOK AI feature and initiate an AI scan, post and page text is sent to your chosen AI provider for contextual grammar analysis. This only occurs when you explicitly click “Scan” with AI enabled. API keys are encrypted with AES-256-CBC and stored on your server.
OpenAI 
* Service: <a href="https://openai.com" rel="nofollow ugc">https://openai.com</a> 
* Terms of Use: <a href="https://openai.com/policies/terms-of-use" rel="nofollow ugc">https://openai.com/policies/terms-of-use</a> 
* Privacy Policy: <a href="https://openai.com/policies/privacy-policy" rel="nofollow ugc">https://openai.com/policies/privacy-policy</a>
Anthropic (Claude) 
* Service: <a href="https://www.anthropic.com" rel="nofollow ugc">https://www.anthropic.com</a> 
* Terms of Use: <a href="https://www.anthropic.com/legal/consumer-terms" rel="nofollow ugc">https://www.anthropic.com/legal/consumer-terms</a> 
* Privacy Policy: <a href="https://www.anthropic.com/legal/privacy" rel="nofollow ugc">https://www.anthropic.com/legal/privacy</a>
Google (Gemini) 
* Service: <a href="https://ai.google.dev" rel="nofollow ugc">https://ai.google.dev</a> 
* Terms of Use: <a href="https://ai.google.dev/gemini-api/terms" rel="nofollow ugc">https://ai.google.dev/gemini-api/terms</a> 
* Privacy Policy: <a href="https://policies.google.com/privacy" rel="nofollow ugc">https://policies.google.com/privacy</a>
xAI (Grok) 
* Service: <a href="https://x.ai" rel="nofollow ugc">https://x.ai</a> 
* Terms of Use: <a href="https://x.ai/legal/terms-of-service" rel="nofollow ugc">https://x.ai/legal/terms-of-service</a> 
* Privacy Policy: <a href="https://x.ai/legal/privacy-policy" rel="nofollow ugc">https://x.ai/legal/privacy-policy</a>
OpenRouter 
* Service: <a href="https://openrouter.ai" rel="nofollow ugc">https://openrouter.ai</a> 
* Terms of Use: <a href="https://openrouter.ai/terms" rel="nofollow ugc">https://openrouter.ai/terms</a> 
* Privacy Policy: <a href="https://openrouter.ai/privacy" rel="nofollow ugc">https://openrouter.ai/privacy</a>
<h4>Licensing & Analytics — Freemius</h4>
Spellmatic uses the Freemius SDK for license validation, plan management, and optional opt-in usage analytics. You are asked for consent during plugin activation.
<ul>
<li>Service: <a href="https://freemius.com" rel="nofollow ugc">https://freemius.com</a></li>
<li>Terms of Use: <a href="https://freemius.com/terms/" rel="nofollow ugc">https://freemius.com/terms/</a></li>
<li>Privacy Policy: <a href="https://freemius.com/privacy/" rel="nofollow ugc">https://freemius.com/privacy/</a></li>
</ul>
<h4>Perfect For</h4>
<ul>
<li>Agencies managing multiple client WordPress sites</li>
<li>Bloggers with large back-catalogues who want to clean up old posts</li>
<li>WooCommerce stores where typos hurt credibility and conversions</li>
<li>Content publishers who need a quick pre-launch proofread</li>
</ul>

Spellmatic

Scan and fix spelling and grammar errors across your entire WordPress site in one click — including Elementor, Avada, Divi, and WPBakery content.

RedPen WordPress plugin vs Spellmatic