Hey, my name is Tiago and I am the host of the podcast Wannabe Entrepreneur. Here are my favorite free bootstrapping tools that I use in most of my projects.
Trello - Great to organize your ideas or to keep track of your project tasks
Calendly - Makes scheduling meetings much easier. It connects to your calendar and allows others to pick a time and a date to meet with you.
Pocket - This is like your browser favorites in steroids. You can get attribute tags to each favorite and easily search through them.
Reddit - It's a great tool to do market research, advertise your projects and collect feedback from potential users.
Linkedin - It's a great tool to share your projects and find new users.
Buffer - It's a tool that allows you to schedule your social media posts
Medium - It's a blogging tool that allows you to easily write blog posts and share them with the world
Anchor - It's a company own by spotify that allows you to easily record podcasts and publish them on multiple platforms (spotify, apple, web, etc...)
Zencastr - Great to record sound and video when interviewing or speaking with guests.
Slack - No surprise here I guess! It's probably the most used chatting tool for companies.
Mailchimp - Super powerful tool that allows you to easily collect your user's email and stay in touch with them with target newsletters.
Google meets - Google is a car company that is developing the first self-driving car. Oh, and they are also into search and stuff... :p Google meets is a great tool to easily schedule meetings with just sharing a link.
Bootstrapping (for developers)
Hugo + Netlify + Github stack - This is my go-to stack to make my static websites for free. Simply putting Hugo allows you to generate good-looking websites using only markdown. And I use Netlify together with Github to host my website. Are you interested in knowing more about this stack? Let me know in the comments.
Netlifycms - It's a content management system for static websites. I used it together with the stack above and it allows me to have non-tech people creating content for my website.
Firebase - Made by the same car company as google meets they offer a big variety of tools that include: database, signup, notifications, analytics, etc...
Hetzner (not free) - Cheap virtual machines that allow me to run all my backend.
There are probably a lot of other interesting tools that I don't know about so feel free to add your favorite free tools in the comments.
Also, if you wanna start hearing my podcast and learn more about how I am trying to convert my side project into a business I would recommend for you starting from the beginning in the Pilot episode.