How Slack Became a $28B Company Without Ads

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Most companies are begging to be noticed. They throw money at ads, spam your inbox with random emails, and jump on whatever’s trending - just for people to tune it out.

Slack did none of that.

In 2013, they launched with just one goal: make workplace communication less annoying. Within a year, they had 8,000 paying customers. Soon, they hit 10M+ daily users.

The secret? They built a product so good, people had to invite their teammates.

Let’s break down how Slack turned workplace FOMO into fuel, designed onboarding like a viral loop, and rewrote the B2B growth playbook.

Step 1: Design a Product That Spreads Naturally (Like a Cold)

Most B2B tools solve a problem. Slack solved a feeling.

Before Slack, teams were stuck in messy email threads and random chat apps. Work felt slow and isolating.

Slack didn’t just pull all the messages into one spot. They created a digital “office” where work happened. But here’s the thing:

Slack only works if your team is on it.

This built in network effect meant every user became a recruiter.

Why it worked:

• FOMO was the fuel: If one person used Slack, teammates had to join to stay in the loop.

• Invites were baked into the UX: You couldn’t send a message without prompting others to sign up.

• It felt human: GIFs, emojis, and casual channels made work fun and sharable.

Takeaway: Build a product that’s naturally social. If it’s not, add features that force collaboration.

Step 2: Let Your Users Sell for You (The “Trojan Horse” Tactic)

Slack’s first users weren’t CEOs or IT managers. They were developers and small teams.

Here’s how they spread:

1. A developer would start using Slack for their team.

2. That team’s marketing department would hear about it.

3. Marketing adopts Slack, then tells the sales team.

4. Soon, the whole company migrates.

Slack called this “bottom up adoption”, infiltrating companies through individual teams instead of top down mandates.

The genius:

• No approval needed: Teams could start free without IT’s permission.

• Data spoke for itself: Slack tracked how messages reduced email volume, then auto generated reports to convince execs.

• It scaled in silence: By the time IT noticed, entire departments were hooked.

Steal this: Target the easiest user in an organization first (like individual contributors), then let them upsell internally.

Step 3: Turn Onboarding Into a Game (The “10,000 Message” Rule)

Slack’s founders discovered something wild:

Once a team sent 10,000 messages in Slack, they almost never left.

So they designed onboarding to hit that number fast:

• Pre loaded content: New users saw example messages, files, and channels (making the app feel alive, even if they were alone).

• Celebratory nudges: “You’ve sent 100 messages! Invite 3 teammates to keep the momentum!”

• Bot driven guidance: Slackbot sent tips like “Type /giphy [word] to send a GIF” to boost engagement.

Result: Teams hit the “aha moment” faster, making them addicted before they realized it.

Copywriting hack: Use empty states (like blank screens) to prompt action. Example: “This channel is quiet. Invite teammates or message Slackbot for help!”

Step 4: Obsess Over “Daily Active Users” (Not Revenue)

Most B2B companies focus on logos and MRR. Slack obsessed over DAU.

Why?

If people used Slack daily, expansion revenue would follow.

They tracked:

• How many messages teams sent

• How many apps they integrated (like Google Drive or Zoom)

• How many channels they created

Then, they used this data to:

• Identify power users (and turn them into advocates)

• Spot at risk teams (and send personalized re-engagement tips)

• Upsell paid features after dependency was built

Growth hack: Offer a free tier so robust that users outgrow it. Slack’s free plan capped message history, so fast growing teams had to upgrade.

The Takeaway: Growth Is About Human Behavior

Slack didn’t win by being the first chat app. They won by understanding how humans adopt tools:

1. Make it contagious: Build a product that’s useless alone but unstoppable with others.

2. Remove approval barriers: Let small teams adopt you first, then grow silently.

3. Design for addiction: Celebrate engagement milestones like a video game.

4. Upsell with data: Show users exactly how much they need you.

Most founders chase growth hacks. Slack mastered human hacks.

Key Lessons from Slack’s Growth:

• FOMO > features: Build a product that’s better with others.

• Infiltration > persuasion: Let users sell internally for you.

• Track daily habits, not just revenue: Engagement predicts longevity.

• Free tiers are sales funnels: If they stay, they’ll pay.

Until next time,
Omar Waseem

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