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If you have a local website, then posting to directories is foundational to local SEO, and for that I recommend Moz's own service: https://moz.com/products/local It's effective and cost-effective. Just make sure you have Google My Business set up first or it won't work out real well for you. You'll find several businesses besides Moz also offer this service as a core part of doing SEO. Now if you're not a local business, it's still not bad practice to post to directories, especially if they are well established authorities within your niche. That's just good outreach.