I have found listing startup in web directories help bring more users. This massive list of web app directories put up by Justin Mcgill really saved me a lot of time.

He had made this list way back in 2014 and some of the links were not working when I tried. So I put up this list of all working links of web directories, along with some more that work today. I have informed him as well so that he can keep his list updated. 

Let me know if you find any relevant web directories missing. Or if any are not working. I ll update this list. 

http://101bestwebsites.com/

http://alternativeto.net/

http://angel.co/

http://appiod.com/submit-app-for-review/

http://apps400.com/submit-your-application-for-review

https://www.astrogrowth.com/

http://betali.st/

http://capterra.com/vendors

http://crozdesk.com

http://crunchbase.com/

http://digg.com/submit

http://en.webrazzi.com/contact/

http://f6s.com/

http://feedmyapp.com/submit/

http://geekopedia.me/startupsubmit

http://geekwire.com/startup-list/

http://launchingnext.com/

http://leanstack.io/

http://mevvy.com/

http://news.ycombinator.com/

http://nextbigproduct.net/product-submission/

http://pineapple.io/resources/new

http://plus.google.com/communities/100445483815501942968

http://producthunt.com/

http://reddit.com/r/sideproject

http://reddit.com/r/startups

http://sideprojects.in/

http://startupbuffer.com

http://startupdope.com/submit-news/

http://startupregister.net/register-your-startup/

http://techpluto.com

http://thestartuppitch.com/post-a-pitch/

http://thetechpanda.com/submit-a-startup/

http://tools.robingood.com/

http://vbprofiles.com

http://venturebreak.com/questions/

http://webapprater.com/webapprater-free-app-review

http://webdevtwopointzero.com/submit-a-site/

http://www.allstartups.info

http://www.designernews.co/

http://www.killerstartups.com/submit-startup/

http://www.new-startups.com/

http://www.nextbigwhat.com/contact/

http://www.nibletz.com/submit-startup

http://www.paggu.com/

http://www.really-aweso.me/submit-your-startup/

http://www.sociableblog.com/contact-us/

http://www.startupblink.com

http://www.stumbleupon.com/submit

http://www.vbprofiles.com/

http://www.youngupstarts.com/

http://www.youngupstarts.com/contact/

https://apprater.net/add/

https://betapage.co/

https://beterest.com/submit-startup/

https://boingboing.net/sub/

https://inc42.com/startup-submission/

https://signupfirst.com/

https://startup88.com/

https://startupbeat.com/startup-beat-featured-startup-pitch-guidelines/

https://venturebeat.com/2017/03/07/how-to-send-story-tips-securely-to-venturebeat/

https://www.discovercloud.com/become-a-vendor

https://www.g2crowd.com/

https://www.moblized.com/vendors/register

https://www.reddit.com/r/AlphaandBetausers

https://www.reddit.com/r/Coupons

https://www.reddit.com/r/DesignCritiques

https://www.reddit.com/r/IMadeThis

https://www.reddit.com/r/IndieBiz

https://www.reddit.com/r/LadyBusiness

https://www.reddit.com/r/RoastMyStartup

https://www.reddit.com/r/ShamelessPlug

https://www.reddit.com/r/SmallBusiness

https://www.sideprojectors.com/project/home

https://www.snapmunk.com/submit-your-startup/

https://www.startupinspire.com/login

https://www.startupranking.com/

https://www.trustradius.com/