1. Meetup.com & Networking Events
This is the most obvious way to meet a startup cofounder. Depending on your geographic area, there should be at least a handful of business, technology, or startup-related meetup.com events going on every month.
For example, I searched meetup.com for the terms “startup” and “entrepreneurship,” filtered by “within 5 miles of NYC,” ad got the results below. You would then find out when these groups meet, mark them down on your calendar, and get ready to mingle!
Believe it or not, I met my first co-founder this way and we went together to build a music-related website while in college and also launched a small a web development business.
You can also seek out other networking events to meet potential technical or business cofounders. The first time you meet someone that is part of your local area ecosystem, I’d ask if there are any events, listserves, newsletters, or organizations that you should be aware of.
Usually, if you don’t know where to start, local incubators, accelerators, and technology-related co-working spaces will put on events or help you find the organizations that do. I also find that Eventbrite is a great way to find networking events, though they usually cost $$. I’ve included a snapshot below, where I searched “entrepreneurship” and filtered by my location and most recent upcoming events.
You could also subscribe to Startup Digest to see the startup-related events that are happening in your area each week. This list compiles events all over the world, including USA, Europe, Australia, Russia, Asia, Canada, and more.
2. Founder Matching Websites
Some of the top cofounder dating or founder matching websites include:
1. CoFoundersLab – “Join the largest community of more than 25,000 founders, advisers, and interns to help launch or grow your business.” CoFoundersLab also puts on events around the US to help entrepreneurs find a cofounder.
2. CollabFinder – “CollabFinder Groups give your community members a place to team up and launch projects.”
3. FounderDating – “FounderDating is the premiere online network for entrepreneurs to connect with cofounders & advisors and find cofounders to work with on their next venture.”
4. Founder2Be – “Find a co-founder. Founder2be is the largest startup community for developers, web designers, marketers and anyone looking to start a startup worldwide.”
5. FoundersNation – “Find or Become a Startup Co-Founder in Israel, New York or London. Co-Founders Wanted.”
** Did I leave out your website? Leave a comment on this article!
I’ve found a cofounder through CoFoundersLab in the past. We worked on this application.
3. Hackathons
Hackathons are a great way to meet programmers and potential technical cofounders. I think the best way to find hackathons in your area is to get plugged in to the local tech scene and ask around. You can just google “hackathons in ___” or try using Eventbrite, like I did below.
You can also search websites like Hackathon.io to browse local hackathons or find a hackerspace in your area using this tool.
There are also larger, well-known events like Startup Weekend, where you need to register in advance.
4. Online Communities
Online communities are a good way to get to know potential cofounders before working together. Usually, the communities are centered around sharing content, providing feedback, or discussing industry news. The one problem with online communities is that it’s difficult to find someone in your area, but I still find them to be very valuable. I found one cofounder I am still working with via one of my own online forums.
1. Startups Subreddit – “A community for all backgrounds, levels of expertise, and business experience. We are a forum of entrepreneurs working towards unbiased and anonymous feedback, advice, ideas, and discussion.”
2. Digital Point Forum – A massive online community that includes sections on: programming, business, and internet marketing.
3. StartupNation Forum – The forum attached to StartupNation, a entrepreneurship blog and resources.
4. Warrior Forum – The #1 internet marketing forum in the world.
5. JointBF – Formerly “teen business forum” this community now accepts entrepreneurs of all ages.
6. KickstarterForum.org – A community for creative types, inventors, and more.
There are many more LinkedIn groups that you can join related to programming, business, or internet marketing. I also recommend joining some that are made up of members in your target market.
I’ve also included a few google+ groups related to startups and entrepreneurship. Again, there are a lot to choose from whether you are looking for a programmer or someone who can drive traffic to your new application. 
5. Produce Great Work
Remember that entrepreneurs have found business partners for hundreds of years before the internet existed. The best way to attract another high-quality entrepreneur is to produce great work yourself. Not only does it demonstrate that you have something to bring to the table, but it also lessens the worry that you will leave your business partner hanging and stop working hard at some point during the venture.
If you’re a programmer, build up your GitHub profile and produce working prototypes. If you’re a so-called “sales expert” prove it with your sales record! If you are a killer “internet marketer,” then be able to demonstrate that via sales, traffic stats, and SEO results.
Everyone, when they are first starting out, thinks it’s about money or fundraising. It couldn’t be farther from the truth. I’d pick a cofounder who is willing to hustle and has a respectable skill set over a cofounder that has money to jumpstart the venture any day of the week.
If you’re only contribution to the venture is that you have money saved or have read up on what it takes to start a company, you are in trouble. Focusing on producing great work and being really good at something will not only increase your chances of success, but will also make it easier to attract a cofounder with a complementary skill set.
6. Local Colleges and Universities
A lot of local college and university have entrepreneurship departments, technology departments, and graduate school programs in business. If you’re not affiliated with the university, you might have to do some networking with people who are to get invited to events, but more often than not, I’ve found that universities are receptive to allowing outside members to attend events or network with graduate students if they are a “guest.”
7. Work With A Lot Of People
The longer that I do this, the more I think it’s crucial that you work with a lot of people on very small projects that may not matter in the grand scheme of things, but that will give you some feedback on their working style, commitment level, passion, and interests.
Someone could look great on paper, but be horrible at time management or quickly lose interest with every new project they do. Finding a cofounder is a lot like dating, and when you are business partners, it’s like marriage. You might get lucky on the first try, but you should go to lengths to avoid a land mine that could lead to legal issues and headache.
Get to know people gradually by doing small projects with them and when you find out you like them and work well together, consider doing larger projects.
8. Meet Angel Investors and Mentors
In my experience, the best angel investors and mentors are very well networked and therefore can connect you with the right people.
A mentor is usually familiar with several different local entrepreneurs and can introduce you to people who may have complementary skill sets or similar values/vision. He or she is the person who says “you guys should talk, I think you would hit it off.”
When you are starting out, you won’t know many people in the community so forming a relationship with a person who does will increase the chances of finding a suitable cofounder.
9. Co-working spaces, Incubators, and Accelerators
Just like universities, co-working spaces, incubators, and accelerators are in the business of educating their members to increase the chances of their success. They often times put on networking events and presentations related to technology, entrepreneurship, and marketing. These are opportunities for you to meet other entrepreneurs.
Just because some of these entrepreneurs are involved in startups already doesn’t mean you shouldn’t network with them. You never know if you will work together on a project in the future and who they may be able to introduce you to.
I also recommend that if you have an expertise in a certain area (like social media, or sales), that you offer to speak at one of the events. It might seem a little presumptuous, but if you have the credentials to back up your skills, it’s a great way to quickly set yourself apart from the pack and become better known in the community.
10. Help Out a lot of People.
Finally, I think the golden rule in this process is to be helpful. The more people you help, even in small ways, the more business relationships you will develop and the better known you will become in the community as someone who is helpful, honest, and hard-working, which is the type of person other entrepreneurs want to work with.
This is a priceless asset and can become a part of your overall personal brand. You never know who might say “Oh, you should meet so and so. You guys are both working in this industry and he’s a great guy.” Sounds like dating right? Haha. It is. Good luck!
Did you find this article to be helpful?
Let me know in a comment below! Also – I’d love to hear other ideas or ways you have met (or think you can meet) a startup cofounder.