Side Projects That Became Empires

Some of the world's most valuable companies started as weekend projects. Here are the stories behind the side hustles that became empires—and the lessons they teach about building in your spare time.

The Accidental Billionaires

Twitter: A Podcast Side Project

The Origin: In 2006, Jack Dorsey was working at Odeo, a podcasting company. When Apple announced iTunes would support podcasts, Odeo's business model crumbled. During a company hackathon, Dorsey built a simple SMS-based status sharing service.

The Pivot: What started as "twttr" (inspired by Flickr's vowel-dropping trend) became Twitter when the team realized its potential beyond internal communication.

The Scale: From hackathon project to $44 billion acquisition by Elon Musk in 2022.

Key Lesson: Sometimes the best ideas come from constraints and necessity, not grand visions.

Instagram: A Check-in App Side Feature

The Origin: Kevin Systrom was working at Nextstop while building Burbn, a location-based check-in app with photo sharing features, in his spare time.

The Pivot: After user testing, Systrom realized people only used the photo feature. He stripped everything else and focused solely on photo sharing with filters.

The Scale: Launched in 2010, acquired by Facebook for $1 billion in 2012 with just 13 employees.

Key Lesson: Pay attention to how users actually use your product, not how you intended them to use it.

Slack: An Internal Gaming Tool

The Origin: Stewart Butterfield's team at Tiny Speck was building a game called Glitch. They created an internal communication tool to coordinate their remote team.

The Pivot: When Glitch failed, they realized their internal tool was more valuable than the game itself.

The Scale: Launched publicly in 2014, went public in 2019 with a $20 billion valuation, acquired by Salesforce for $27.7 billion in 2021.

Key Lesson: Sometimes the tools you build to solve your own problems are more valuable than your main project.

The Weekend Warriors

Buffer: A Landing Page Experiment

The Origin: Joel Gascoigne wanted to test if people would pay for scheduled social media posting. He built a simple landing page over a weekend with fake "plans" and a "coming soon" message.

The Validation: When people clicked "plans," he knew there was demand. Only then did he build the actual product.

The Scale: Grew to millions of users and tens of millions in revenue, all while maintaining a transparent, remote-first culture.

Key Lesson: Validate demand before building. A landing page can test your hypothesis faster than months of development.

Mailchimp: A Web Design Agency Side Project

The Origin: Ben Chestnut and Dan Kurzius ran a web design agency. Clients kept asking for email marketing tools, so they built one as a side project in 2001.

The Growth: They kept their day jobs for years, slowly growing Mailchimp on nights and weekends.

The Scale: Bootstrapped to $700 million in annual revenue, sold to Intuit for $12 billion in 2021.

Key Lesson: Bootstrapping allows you to maintain control and grow sustainably without external pressure.

Basecamp: A Project Management Side Tool

The Origin: Jason Fried and DHH at 37signals were building client websites but struggling with project management. They built Basecamp to organize their own work.

The Realization: Clients loved their project management tool more than their web design services.

The Scale: Pivoted entirely to Basecamp, grew to millions of users while maintaining a small team and strong opinions about work-life balance.

Key Lesson: Your biggest pain point might be someone else's biggest pain point too.

The Accidental Discoveries

Flickr: A Game Feature Gone Viral

The Origin: Ludicorp was building Game Neverending, a web-based game. Photo sharing was just one feature to help players communicate.

The Surprise: Players used the photo sharing feature more than they played the actual game.

The Pivot: They spun off the photo feature into Flickr, which Yahoo acquired for $35 million in 2005.

Key Lesson: Be open to unexpected user behavior. Your side feature might be your main product.

Groupon: A Collective Action Platform

The Origin: Andrew Mason built The Point, a platform for collective action and fundraising. It wasn't gaining traction.

The Experiment: They tried using the platform for group buying deals as a way to demonstrate collective action.

The Explosion: The group buying experiment became Groupon, which went public with a $12.8 billion valuation.

Key Lesson: Sometimes you need to experiment with different use cases for your core technology.

Pinterest: A Mobile Commerce App Feature

The Origin: Ben Silbermann was working on Tote, a mobile shopping app. The "collections" feature where users saved products they liked was barely used.

The Insight: People enjoyed collecting and organizing images more than shopping.

The Pivot: They rebuilt the collections feature as Pinterest, focusing on visual discovery and inspiration.

The Scale: Went public in 2019 with a $10 billion valuation.

Key Lesson: Look for the features users engage with most, even if they're not your main value proposition.

The Modern Success Stories

Discord: A Gaming Communication Tool

The Origin: Jason Citron had sold his previous gaming company and was building a new game called Fates Forever. The team needed better voice chat for coordination.

The Problem: Existing tools like Skype and TeamSpeak were clunky for gamers.

The Solution: They built their own communication platform optimized for gaming communities.

The Scale: Grew to 150 million monthly active users, valued at $15 billion in 2021.

Key Lesson: Sometimes the best opportunities come from improving existing solutions for specific communities.

Zoom: A Better Video Conferencing Tool

The Origin: Eric Yuan was frustrated with existing video conferencing tools at Cisco WebEx. He wanted to build something that "just worked."

The Side Project: He left Cisco and spent years building Zoom with a small team, focusing obsessively on reliability and ease of use.

The Timing: Launched in 2011, but the pandemic in 2020 accelerated adoption dramatically.

The Scale: Went from $623 million revenue in 2020 to $4 billion in 2021.

Key Lesson: Sometimes you need to wait for the right moment. Build great products and be ready when opportunity strikes.

Notion: A Personal Productivity Tool

The Origin: Ivan Zhao was frustrated with existing productivity tools that were either too simple or too complex.

The Vision: He wanted to build "Lego blocks for productivity" that users could combine in infinite ways.

The Journey: Spent years building and rebuilding, nearly running out of money multiple times.

The Scale: Grew to millions of users and a $10 billion valuation by focusing on flexibility and user empowerment.

Key Lesson: Persistence pays off. Sometimes revolutionary products take longer to build and find their market.

What These Stories Teach Us

Pattern 1: Solve Your Own Problem

The most successful side projects solve problems the founders personally experienced.

• Slack solved remote team communication
• Basecamp solved project management chaos
• Buffer solved social media scheduling pain
• Zoom solved video conferencing frustration

Pattern 2: Start Small, Think Big

None of these companies started with grand visions of billion-dollar exits.

• Instagram began as one feature of a larger app
• Twitter was a hackathon experiment
• Mailchimp was a client service add-on
• Discord was an internal tool

Pattern 3: Listen to Users, Not Your Plan

The most successful pivots came from paying attention to user behavior.

• Instagram users ignored check-ins, loved photos
• Flickr users ignored the game, loved photo sharing
• Pinterest users ignored shopping, loved collecting
• Slack users loved the communication tool, not the game

Pattern 4: Timing Matters, But Don't Wait

Great products often succeed when the market is ready, not when they launch.

• Zoom was ready when remote work exploded
• Discord grew when gaming communities needed better tools
• Notion succeeded when people wanted more flexible productivity tools

Pattern 5: Constraints Breed Creativity

Limited resources force focus and innovation.

• Small teams move faster and make decisions quicker
• Limited budgets force creative solutions
• Time constraints prevent over-engineering
• Personal pain points ensure product-market fit

How to Build Your Own Empire

Start With a Real Problem

Ask yourself:

• What frustrates you daily?
• What tools do you wish existed?
• What processes could be simpler?
• What communities do you belong to that have unmet needs?

Build the Minimum Viable Solution

Don't try to build everything at once:

• Solve one specific problem really well
• Use existing tools and services where possible
• Focus on core functionality first
• Get feedback early and often

Validate Before You Scale

Test demand before investing heavily:

• Build landing pages to gauge interest
• Create mockups and get user feedback
• Start with a small, engaged community
• Measure engagement, not just signups

Stay Close to Your Users

The most successful founders never stop talking to users:

• Join communities where your users hang out
• Respond personally to support requests
• Ask for feedback regularly
• Watch how people actually use your product

Be Patient But Persistent

Most overnight successes take years:

• Mailchimp grew slowly for a decade
• Notion nearly failed multiple times
• Basecamp started as a side project in 1999
• Buffer validated demand before building

The Side Project Advantage

Lower Risk, Higher Learning

Side projects let you experiment without betting everything:

• Keep your day job while you build
• Learn what works without financial pressure
• Iterate based on real user feedback
• Build an audience before you need revenue

Authentic Problem-Solving

When you're solving your own problem, you understand the user deeply:

• You know the pain points intimately
• You can spot fake solutions quickly
• You have built-in product intuition
• You're your own first customer

Sustainable Growth

Side projects often grow more sustainably:

• No pressure to scale prematurely
• Focus on product-market fit first
• Build strong foundations before rapid growth
• Maintain control over your vision

Common Mistakes to Avoid

Building in a Vacuum

Don't spend months building without user feedback:

• Talk to potential users from day one
• Share early prototypes and mockups
• Join communities where your users exist
• Validate assumptions quickly and cheaply

Perfectionism Paralysis

Don't wait for the perfect product:

• Ship early and iterate based on feedback
• Focus on core functionality first
• Use existing tools and services where possible
• Perfect is the enemy of good enough

Ignoring the Business Model

Think about monetization from the beginning:

• How will you make money?
• Who will pay and how much?
• What's your path to profitability?
• How will you compete with free alternatives?

Scaling Too Early

Don't try to grow before you have product-market fit:

• Focus on a small group of passionate users first
• Make sure people love your product before marketing it
• Understand your unit economics before spending on growth
• Build systems that can handle growth when it comes

The Future of Side Projects

AI-Powered Development

New tools are making it easier to build side projects:

• AI code generation speeds up development
• No-code platforms lower technical barriers
• Cloud services reduce infrastructure complexity
• API ecosystems enable rapid integration

Global Remote Work

Remote work creates new opportunities:

• Access to global talent and markets
• Lower overhead costs for bootstrapped projects
• Distributed teams can work around the clock
• Digital-first business models are proven

Creator Economy Integration

Side projects can leverage creator economy trends:

• Build audiences while building products
• Use content marketing to validate ideas
• Monetize through multiple channels
• Build communities around your products

Your Side Project Could Be Next

The companies in this article started as experiments, side projects, and solutions to personal problems. What they had in common wasn't grand vision or massive funding—it was persistence, user focus, and willingness to adapt.

Your side project might not become the next billion-dollar company, but it could become a sustainable business that gives you freedom, fulfillment, and financial independence.

The best time to start was yesterday. The second-best time is now.

What problem will you solve this weekend?