My indexer recommendation is 100% free, but it takes quite a bit of time and effort.
The good news is that all this time, effort, and energy are well worth it.
This is not a one-and-done or one-time-big-time kind of recommendation.
Instead, I'm talking about investing the time, focus, and energy into developing credibility on Reddit so you can at some point share your links, either through your own subreddit or on specific subreddits that fit your target niche.
This means creating a legit-looking account, participating in actual conversations, establishing some sort of credibility by posting third-party, high-quality content links, and then ultimately starting your own subreddit and cross-posting and getting clicks that way.
If you're able to do this, you can then use your subreddit as an indexing tool for your latest posts.