Version 1.4 · March 2026

Documentation

Everything you need to install, configure, and get the most out of Auto Internal Linker.

Requirements

WordPress 5.0 or higher
PHP 7.4 or higher (PHP 8.x recommended)
At least 5 published posts for the index to be useful
Claude AI Mode (optional): Anthropic API key — console.anthropic.com

Installation

1
Download the plugin
Purchase a licence and download auto-internal-linker.zip from your confirmation email or Lemon Squeezy order page.
2
Upload in WordPress admin
Go to Plugins → Add New → Upload Plugin. Select the ZIP file and click Install Now.
3
Activate the plugin
Click Activate Plugin. The plugin immediately begins building the keyword index in the background.
4
Enter your licence key
Go to Settings → AIL License and enter the licence key from your purchase email.
5
Open settings
Navigate to Settings → Auto Internal Linker. Review defaults — they are safe for most sites out of the box.
6
Rebuild the index
Click Rebuild Index Now. Watch the keyword count appear. For 90 posts, expect 200–400 keywords.

✅

That's it.

Open any published post in your browser. Scroll past the first paragraph — you should see auto-links in your theme's link colour.

Quick Start

The defaults work well for most sites. Three things worth tuning immediately after install:

1. Customise your blacklist

Add words that appear in many post titles but shouldn't become anchors. For a cooking site: recipe, easy, best, simple, homemade. Go to Settings → Blacklist, add one per line, save and rebuild.

2. Set anchor length

The default is 1–3 words. Set Min anchor words to 2 to prevent single-word anchors like "diving" or "reef" from being linked.

3. Verify on a post

Open a long post (800+ words). You should see 3–6 auto-links in the body, skipping the first paragraph and all headings.

All Settings

All settings at Settings → Auto Internal Linker in your WordPress admin.

Link Behaviour

Setting	Default	Description
max_links_per_post	6	Maximum auto-links per post. Recommended: 5–8 depending on post length.
max_links_per_kw	1	How many times the same keyword can be linked within one post.
link_target	_self	Open links in the same tab (_self, good for SEO) or new tab (_blank).

Spacing & Placement

Setting	Default	Description
min_words_between	100	Minimum word gap between any two auto-links.
skip_first_n_paras	1	Skip the first N paragraphs. Keeps intros clean.
skip_headings	On	Skip all h1–h6 headings.

Keyword Index

Setting	Default	Description
min_keyword_length	4	Minimum character length for a keyword to be indexed.
min_anchor_words	1	Minimum words in an anchor phrase. Set 2 to prevent single-word anchors.
max_anchor_words	3	Maximum words in an anchor phrase.
extraction_mode	smart	smart (colon split) or claude (AI-powered).

ℹ️

Rebuild required.

Changes to keyword index settings only take effect after clicking Rebuild Index Now.

Smart Mode

Smart Mode splits post titles at the colon and treats the part before the colon as the primary keyword source.

Example

Title: "Whale Sharks: A Complete Guide to Swimming With Giants"

Before colon → "Whale Sharks"
Extracted anchors:
  • "whale sharks"      ← primary 2-word phrase
  • "whale"             ← single word (if min_anchor_words = 1)

After colon → shorter phrases only, boilerplate filtered
  • "complete guide"

💡

Best for:

Sites with consistently formatted titles like Topic: Subtitle. If your titles don't use colons, consider Claude AI Mode.

Claude AI ModeAI

Claude AI Mode sends each post title to the Anthropic Claude API and receives back 3–6 high-quality keyword phrases with full semantic understanding — not just word patterns.

Setup

1
Get an Anthropic API key
Sign up at console.anthropic.com. Add a small credit ($5 will index thousands of posts).
2
Enter the key in settings
Go to Settings → Auto Internal Linker → Extraction Mode → Claude AI Mode. Paste your API key.
3
Rebuild the index
Click Rebuild Index with Claude AI. May take 5–30 seconds depending on post count.

Cost

Uses the claude-haiku-4-5 model — the fastest and most affordable in the Claude family.

Posts	Estimated cost
100 posts	~$0.005
1,000 posts	~$0.05
10,000 posts	~$0.50

💡

Minimal cost.

The index rebuilds once daily and on each post save — not on every page load.

Blacklist

The blacklist prevents specific words from being used as anchor text. One word or phrase per line. Case-insensitive.

Examples

# Generic words
guide
best
how to
tips

# Niche-specific (travel site)
australia
queensland
travel
visiting

⚠️

Rebuild required.

Blacklist changes only take effect after rebuilding the index.

How the Keyword Index Works

On activation (and once daily), the plugin queries all published posts, extracts keyword phrases from each title, and stores the resulting keyword → {post_id, url, title} map in wp_options. No custom database tables are created.

The index also rebuilds whenever a post is saved or deleted, and when you click Rebuild Index Now.

Keywords are sorted longest-phrase-first so "whale shark season" is tried before "whale shark" before "whale" — the most specific phrase always wins.

How Link Injection Works

The plugin hooks into WordPress's the_content filter at priority 20. On each page load:

Split into paragraphs — at <p> boundaries
Skip early paragraphs — first N passed through untouched
Split into text nodes — at HTML tag boundaries
Skip tags — existing <a> and <h1>–<h6> skipped
Match keywords — each text node checked against the index
Enforce limits — word gap, per-post max, per-keyword max, self-link check
Inject link — keyword wrapped in <a> tag

🛡️

Zero database writes.

Injected HTML is never saved to the database. Deactivate the plugin — original content reappears immediately, unmodified.

Regex Matching

Uses explicit lookbehind/lookahead instead of \b word boundaries:

/(?<![a-zA-Z0-9\-])(keyword phrase)(?![a-zA-Z0-9\-])/iu

This prevents partial matches inside hyphenated words. The i flag enables case-insensitive matching; the u flag enables full Unicode support for international sites.

Text nodes are decoded with html_entity_decode() before matching so that HTML entities like ’ (curly apostrophe) are never split by the regex.

FAQ

Does the plugin modify my post content in the database?▼

No. All injection happens via the the_content WordPress filter on each page load. Your original post content is never touched. Deactivate the plugin and all auto-links disappear instantly.

Why aren't links appearing on my posts?▼

Check: (1) Is your licence active? Settings → AIL License. (2) Is the index built? Check keyword count. (3) Does your post have enough words? The word gap (100 words default) means short posts may get no links. (4) Are all keywords on the blacklist?

How many links should I set per post?▼

A common SEO guideline is one internal link per 200–300 words. For 1,000 words, 3–5 links is natural. The default of 6 is conservative. Avoid going above 10.

Does it work with Elementor, Divi, etc.?▼

It works with any theme or builder that uses the standard WordPress the_content filter, which includes Elementor, Divi, Beaver Builder, and most others.

Will it slow down my site?▼

The overhead per page load is under 5ms. The index loads from wp_options (one cached DB read) and all processing is in-memory.

What happens when I deactivate the plugin?▼

All auto-links disappear — because they were never saved to the database. The plugin also clears the index from wp_options on deactivation.

Can I move my licence to a different site?▼

Yes. Go to Settings → AIL License, click Deactivate License to free a slot. Then activate on the new site.

Troubleshooting

No links appearing at all

Check licence status: Settings → AIL License
Check keyword count — if 0, click Rebuild Index Now
Make sure you're viewing a single post, not a category or homepage
Disable other SEO plugins temporarily to check for conflicts

Broken apostrophes or special characters

Update to v1.3.1 or later. Fixed in v1.3.1+.

Too many links / looks spammy

Reduce Max links per post to 4–5
Increase Min words between links to 150–200
Set Min anchor words to 2
Expand your blacklist

Claude AI Mode not working

Check your API key starts with sk-ant- and has credits
Check console.anthropic.com for usage and errors

Index not rebuilding automatically

The daily rebuild uses WordPress cron (wp-cron.php). If your host disabled WP-Cron, trigger a manual rebuild via the settings panel, or set up a real server cron.

Changelog

See the full Changelog page for detailed release notes.

v1.4.0 — March 2026 Latest

Licence key system via Lemon Squeezy
Settings → AIL License admin page
Background licence validation via daily cron
Admin notice when licence inactive or expired

v1.3.1 — March 2026

Fixed: HTML entities corrupted by regex matching

v1.3.0 — December 2024

Min/Max anchor words setting
Skip headings option

v1.2.0 — November 2024

Smart Mode and Claude AI Mode
Searchable keyword preview

v1.1.0 — October 2024

Renamed to Auto Internal Linker
Fixed partial word match bug

v1.0.0 — September 2024

Initial release