This site is a web directory, so treat what follows accordingly. It is written to be accurate rather than flattering, because the flattering version of this answer is what got the whole category a bad reputation.

What a web directory is

A web directory is a list of websites organised by subject, with each entry reviewed and placed in a category by a person rather than by a crawler. That human curation is the entire distinction from a search engine, which indexes automatically and ranks algorithmically.

Directories were how the early web was navigated. Yahoo began as one. The model declined because it does not scale: a person can categorise thousands of sites, not billions, and once search worked well enough, browsing a taxonomy stopped being how anyone found things.

The honest answer about SEO value

For most of the 2000s, directory submission was a standard link building tactic, which produced thousands of directories that existed solely to sell links. Google's response was decisive and is still in force: bulk directory submission is treated as a link scheme, and low-quality directory links are discounted or penalised.

So the direct answer to "are they worth it for SEO" is: largely no, and anyone telling you otherwise is probably selling submissions. Submitting to five hundred directories is a recognisable footprint and a liability rather than an asset.

The exceptions are narrow and real:

• Local citations. For a business with a physical location, consistent name, address and phone listings across directories are a recognised local search input. This is about consistency of business data, not about links.
• Industry and trade listings. A professional body, trade association or specialist listing in your field is a normal thing for a real business to be in, and carries some weight precisely because membership implies something.
• Genuinely browsed directories. A small number of subject-specific directories still have actual readers. A listing there can send real visitors, which is worth more than a link.

How to judge whether a directory is worth submitting to

A short checklist, which this directory is equally subject to:

• Does a human review submissions? A directory that accepts everything is filtering nothing, and a list with no filter carries no information.
• Is it free, or is the fee proportionate? A modest review fee is defensible. A high fee tied explicitly to a "dofollow" link is selling links, and participating carries the risk.
• Are the categories populated? A directory with two hundred categories and forty listings is a template that was never filled in.
• Are the listings still alive? Click a few. A directory full of dead links is not maintained, and an unmaintained list is worthless regardless of its other qualities.
• Would you use it? If you would never browse it yourself to find anything, it is unlikely anyone else does either.

What a directory is still genuinely good for

Two things, both modest.

The first is discovery of the middle layer of the web. Search results are dominated by large platforms, and the specialist sites, single-subject archives and independent projects that would actually answer a niche question rarely surface. A curated list is one of the few remaining ways to encounter them.

The second is a small amount of referral traffic for the listed site, from people browsing a category rather than searching a phrase. Modest, but it is real traffic from a human, which is a different thing from a link.

The realistic conclusion

Directory submission is not a growth strategy, and treating it as one wastes time that would be better spent on your own pages. Being listed in a handful of relevant, maintained directories is a normal part of existing on the web, costs very little, and occasionally sends someone useful your way. That is the whole of it, and any pitch promising more than that should be read as a warning.