If you want something that actually scales on WordPress, I’d split it into two buckets:
in-editor suggestions vs
rule-based auto linking. In my experience, the “perfect” tool doesn’t exist — you pick the trade-off you can live with.
Good WP options
- Link Whisper – probably the best balance for most sites. It suggests internal links as you write, and you can bulk-add links across older posts. It’s not magic, but it cuts the manual grind hard.
- Yoast Premium – internal linking suggestions are OK if you’re already on Yoast, but I find it weaker than Link Whisper for bulk work.
- Internal Link Juicer – best if you want rules (keyword → URL) and semi-automated linking. Useful for affiliate/content sites, but you need to keep it on a tight leash or you end up with spammy, repeated anchors.
What I do on bigger sites
I use Link Whisper for day-to-day editorial, then every month I run a crawl in Screaming Frog to find orphan/low-internal-link pages and fix them in batches. GSC also helps: take pages getting impressions but sitting page 2/3 and point a few strong internal links at them from relevant older posts.
If you want “set and forget”, Internal Link Juicer is closest — but I still prefer suggestions + human approval for anything that matters.