Celi's Original Decision

On Friday, Alex Lieberman, Co-founder of Morning Brew, shocked me when he posted this:

My LinkedIn exploded with notifications, and I've spent the last 36 hours engaging with the over 400 people who interacted with the post.

Those conversations led me to write this piece on Celi's original decision to build a multi-player product instead of a single-player product.

To those who championed Celi in the comments of Alex's post: thank you from the bottom of my heart — this one’s for you.

Two years ago, Celi set out to solve a problem that affects most of us — forgotten birthdays and beyond dates.

If you’ve ever forgotten one, you’re not alone:

• 92% of people have forgotten a birthday

• 76% have forgotten an important life date

• 75% have tried and failed to solve this with calendars or apps

Early on, we had to decide whether to solve this with a single-player or multi-player product.

This choice laid the foundation for Celi’s vision to transform how we maintain and nurture our relationships.

Here’s why we believe a multi-player approach is the key to solving this problem effectively.

Single-player vs Multi-player products

Before we delve into our decision, it’s important to distinguish between the two approaches to product development:

Single-player (standalone) products

• Work independently without other users

• Value derived from individual interaction

• Examples: task managers, note-taking apps, solo mobile games

Multi-player (networked) products

• Require or benefit from user participation

• Value increases with more users (network effect)

• Examples: messaging apps, social media, collaborative tools

Understanding the Problem

Addressing forgotten birthdays and beyond dates meant solving two interconnected problems:

1. Knowing: Having correct dates in your system. This is the real challenge. Most people lack a comprehensive, up-to-date list of important dates for their connections.

2. Remembering: Notifying users about upcoming dates. Once you have the correct dates, this is straightforward. It involves a notification system linked to an event database.

Many products focus on “remembering,” they assume users already know the dates or will source them.

But that’s not the case.

Celi needed to address both “knowing” and “remembering.”

Exploring Single-Player Solutions

We considered three single-player approaches before deciding on our multi-player solution.

Single-Player Solution #1: Manual Data Entry

The default solution most people consider first is a single-player product where users add dates manually.

Here’s the typical workflow:

1. List everyone important to you

2. Ask for their birthday and other significant dates

3. Wait for responses

4. Manually add each date to your database

5. Set and activate reminders

6. Maintain your database indefinitely

In this, you’ll only know or remember a date if you actively seek it out and remember to add it to this system.

As Kimberly Wilkins famously said, “Ain’t nobody got time for that!”

Moreover, this solution already exists — it’s called a calendar, and research shows it doesn’t effectively solve the problem.

Single-Player Solution #2: Integrating with Existing Platforms

The next solution people often consider is still single-player but integrates with platforms to “pull” known events into the product.

However, this approach has several downsides:

• Facebook: Too many dates, outdated connections

• LinkedIn: Primarily professional connections, not personal

• Google Calendar: Incomplete data, limited to dates you’ve entered

• iOS: Incomplete data, restricted to SMS

Plus, these platforms are limited to only birthdays.

You’d miss all the “beyond the birthday” dates that Celi users add to their profiles.

To capture these additional important dates or fill in any incomplete data not pulled in, you’d still need to resort to the manual steps in single-player solution #1…

This keeps you as both the workhorse and the point of failure.

Single-Player Solution #3: Automated Collection via Unique Links

The third solution, while still single-player, introduces unique links to automate the data collection process.

Here’s how it works:

1. Users distribute their personalized link to friends and family

2. Recipients fill out their info and dates using the link

3. Upon submission, the dates populate the user’s database

4. The user receives reminders for these important dates

This approach makes sense as it eliminates the user as both the workhorse and point of failure.

It was even our first MVP.

But, it’s not the ultimate solution. Here’s what happens in practice:

1. User 1 sends their unique link to Friend 1 → Friend 1 fills it out.

2. User 2 sends their unique link to Friend 1 → Friend 1 fills it out again, but is irritated.

3. User 3 sends their unique link to Friend 1 → Friend 1 doesn’t fill it out.

While this solution benefits users, it creates a redundant workflow for friends.

In time, friends stop filling out forms they’re repeatedly sent and:

• Form conversion rates decline

• The product becomes less useful as databases remain incomplete

• Users ultimately churn

The key to making this solution work is to save Friend 1’s info the first time they submit it, eliminating the need for repeated entries.

This insight led us to Celi’s multi-player approach and is exactly what Celi does.

The Celi Solution: A Multi-Player Approach

Drawing from previous iterations, we established three key principles:

1. Users should only be responsible for entering their own dates and information.

2. Users should not be responsible for entering anyone else’s dates and information.

3. Users should have an easy way to collect important information from others and receive automatic reminders.

Celi addresses these needs through a simple three-step process: Create → Connect → Celi.

Create

Add your own dates and information.

Connect

Build your network in two ways:

• Connect with existing Celi users through a request/accept workflow.

• Send your unique PAC (Pre-Approved Connection) link for others to submit their information.

• Upon connection, profiles, dates, and information are synced between users.

Celi

Receive reminders when your connections have a date to celebrate.

• Notifications sent via SMS + email or WhatsApp + email, based on your country code.

• Future updates will allow customization of notification methods, timing, and muting options.

The Magic of Multi-Player: Celi’s PAC Link

The real magic of Celi lies within the PAC link.

Short for Pre-Approved Connection link, here’s how it works:

1. Share your unique PAC Link with friends, family, or anyone not on Celi yet.

2. When they submit their dates and info, Celi saves their information and creates a profile for them.

3. Celi instantly connects your profiles.

4. At connection, your dates and information are automatically synced to each other and become visible in your upcoming feed.

5. You receive reminders whenever they have a date to celi.

This bypasses traditional request/accept workflows, allowing you to use Celi effortlessly.

There’s more.

Celi also captures and shares all those other important bits of information like addresses, contact information, contact preferences, payment profile links, and friendship languages.

Why else Multi-Player?

Celi’s decision to build a multi-player solution isn’t just great for users — it’s smart business.

We chose this approach for several compelling reasons:

1. Product-Led Acquisition: Users naturally invite others while using the product, reducing marketing costs to near zero. This is widely considered the best channel for customer acquisition.

2. Network Effects: Product becomes more valuable as more people use it, creating a virtuous cycle of growth and engagement.

3. Lean Growth: Avoids reliance on paid, content, or sales-driven growth engines, allowing for more efficient scaling.

4. True Product Validation: Success depends on genuine user value and engagement, providing clear metrics for product-market fit.

5. Sustainable Monetization: Like LinkedIn, the multi-player ecosystem enables a free service while providing premium features that enhance individual experiences.

6. Future Expansion: Sets the foundation for smart-gifting, interest-informed brand offers, and expansion into professional networks.

In summary, this gives Celi the potential to become what Fred Wilson calls his “favorite business model,” and what David Skok terms “the perfect business.”

The Bigger Picture

Now here’s a secret: Celi isn’t really about birthdays or any other dates.

Since 1938, the Harvard Study of Adult Development has been investigating what makes people flourish.

The research reveals that good relationships keep us happier and healthier.

People who are more socially connected to family, friends, and community are happier, healthier, and live longer.

But how do we nurture these relationships?

Robert Waldinger, the study’s current director, shared his approach:

Through the natural use of the product, Celi nudges you to reach out to those friends and family.

The reminders are simply excuses — conversation starters.

Getting started with Celi

One of the five regrets of the dying is “I wish I had stayed in touch with my friends.”

At Celi, we built a product to eliminate that regret.

Is there a relationship in your life that you would like to deepen?

A birthday you want to remember?

A friend’s sobriety, remembrance, or immigration date you want to celi?

Know and remember it for free, with Celi.

To avoid any bias from an unreliable narrator, read our real user reviews, scroll through the hundreds of comments on Alex Liberman’s post about Celi, or listen to one of Celi’s first users:

Special shoutouts to:

• Nicole Foy for launching Silver Sea Apparel’s Low Impact Lifestyle Sports Bra made with TENCEL™ .
  

• Malaika Smyth for launching Good Thoughts Gift Company’s first line of curated gift boxes.
  

• Sara De Ases for launching Served, a premium padel brand made in Colombia.