BBA Internal Link Machine makes internal linking simple and consistent. Define keyword link rules, choose the pages they point to (your “pillar” pages), and the plugin inserts the links into your content – no manual hunting through posts.

Free features

Up to 5 keyword link rules – map a keyword to a target page.
Pillar pages – designate the important pages your rules link to.
Manual, per-post linking – links are applied as you publish or update a post, so you stay in control of what changes.
Basic visual link map – see which rules are linking where.
URL exclusions – keep specific URLs out of automatic linking.
Block & Classic editor support – works with the standard WordPress editors.

The free version runs entirely on your own site and makes no external/third-party API calls.

Pro

Internal Link Machine Pro will remove the free 5-rule limit so you can create unlimited keyword link rules. Pro is not on sale yet; https://bigbad.agency/plugins/internal-link-machine/ will say when it is.

Source Code

All JavaScript and CSS shipped in this plugin (in admin/js/ and admin/css/) is the original, uncompiled, human-readable source. No build tools (webpack, Rollup, npm, Composer, minifiers, transpilers) are used to generate the distributed files – what you install is exactly the source, so it can be read, studied, and modified directly.