About this collection
A free plan you can stay on indefinitely, with paid tiers above it. The most common model in the directory.
By the numbers
6 tools match on this page. 2 of them are open source, so you can read or self-host the code.
How the listings are written
Every entry here was written for this directory rather than copied from the vendor. Each one says what the tool does, who it is a good fit for, and where it stops being one, because a listing that only repeats marketing copy is no use to anyone deciding between three options.
Pricing describes the software itself: free means no payment to use it, a free tier means a plan you can stay on indefinitely with paid tiers above, and paid means there is no free plan. That is separate from whether the listing here was paid for.