What did you learn today?
Coming soon · Private Beta
One question every day. A record of your mind that compounds for years.
Day 12 · 🔥 11
What did you learn today?
Instagram was built to make you feel behind.
TikTok was built to make you forget what you just watched.
X was built to make you angry enough to stay.
Not one of them was built to make you smarter.
You already know something is broken. Nobody's built the alternative. Until now.
The only social app where closing it leaves you smarter than when you opened it.
Day 12 · 🔥 11 day streak
What did you learn today?
How it works
Post
150 characters forces you to actually understand what you learned — not just consume it and move on.
Discover
The feed only unlocks after you post. What's inside is what curious people around the world learned today.
Grow
Every post builds your permanent intellectual profile. Your streak, your topics, your thinking — compounding over years.
The Feed
Every post was written by someone who had to think first. Scroll through that and tell me you didn't learn something.
The human brain can't actually multitask — it rapidly switches tasks. Each switch costs ~23 min of focus recovery.
The Rule of 72: divide 72 by your interest rate to find how many years to double your money.
'Salary' comes from Latin 'salarium' — Roman soldiers were partly paid in salt.
Your Identity
Most platforms know what you watched. Spark knows what you learned. Every post builds a permanent profile — your streak, your topics, your thinking. After a year, it's the most honest picture of a growing mind.
Sander
67
day streak
124
posts
891
reactions
business
top topic
Your Topics
Recent Sparks
"Compound interest at 10% doubles money every 7.2 years. The Rule of 72..."
"The Roman Empire's currency debasement mirrors modern quantitative easing..."
Member since January 2026
Honey never spoils. Archaeologists found 3000-year-old honey in Egyptian tombs — still edible.
The "doorway effect" is real — walking through a door genuinely erases short-term memory. Rooms are mental boundaries.
Amazon was profitable from day one — in books. Bezos stayed unprofitable on purpose to reinvest everything. It was a choice, not a struggle.
Napoleon was once attacked by rabbits. He ordered a rabbit hunt to celebrate Austerlitz — someone brought tame ones. They charged him.
Nietzsche's "amor fati" — love of fate. Not just accepting what happens, but wanting it to have happened exactly as it did.
The first computer bug was a literal bug — a moth stuck in a Harvard relay in 1947. Grace Hopper taped it into the logbook.
Goodhart's Law: when a measure becomes a target, it ceases to be a good measure. Every metric eventually gets gamed.
The word "salary" comes from salt — Romans were paid in it. "Worth their salt" is 2000 years old and still in daily use.
Your body replaces most of its cells every 7-10 years. The you of a decade ago is almost entirely physically gone.
The shortest war in history lasted 38-45 minutes — Britain vs Zanzibar, 1896. Zanzibar surrendered before lunch.
Ego depletion — willpower is finite and depletes like a muscle. Every decision you make makes the next one harder.
IKEA's maze layout is deliberate — it's called the "Gruen effect." Disorientation makes you forget why you came in and buy more.
Honey never spoils. Archaeologists found 3000-year-old honey in Egyptian tombs — still edible.
The "doorway effect" is real — walking through a door genuinely erases short-term memory. Rooms are mental boundaries.
Amazon was profitable from day one — in books. Bezos stayed unprofitable on purpose to reinvest everything. It was a choice, not a struggle.
Napoleon was once attacked by rabbits. He ordered a rabbit hunt to celebrate Austerlitz — someone brought tame ones. They charged him.
Nietzsche's "amor fati" — love of fate. Not just accepting what happens, but wanting it to have happened exactly as it did.
The first computer bug was a literal bug — a moth stuck in a Harvard relay in 1947. Grace Hopper taped it into the logbook.
Goodhart's Law: when a measure becomes a target, it ceases to be a good measure. Every metric eventually gets gamed.
The word "salary" comes from salt — Romans were paid in it. "Worth their salt" is 2000 years old and still in daily use.
Your body replaces most of its cells every 7-10 years. The you of a decade ago is almost entirely physically gone.
The shortest war in history lasted 38-45 minutes — Britain vs Zanzibar, 1896. Zanzibar surrendered before lunch.
Ego depletion — willpower is finite and depletes like a muscle. Every decision you make makes the next one harder.
IKEA's maze layout is deliberate — it's called the "Gruen effect." Disorientation makes you forget why you came in and buy more.
Built by
"I am building Spark as an 18-year-old in Tallinn who got tired of opening Instagram and feeling worse afterward. I believe that social media should be useful, so I am building the platform I wish existed."
— Sander, founder
Opening to the first 500 members only.