Monolith vs Microservices: Why Instagram Went Back

It’s funny, isn’t it?

We engineers love clean architecture diagrams. Services talking over perfect protocols. Diagrams with arrows that feel like they belong in a NASA control room.

And for years, the north star has been clear:

“Break the monolith. Embrace microservices. That’s how you scale.”

But what if I told you one of the biggest tech companies in the world — Instagram — took that advice… and then slowly backed away from it?

Yeah. That happened.

And it turns out, it’s a lot more relatable than you'd expect.

The Monolith That Could

Instagram’s first few years were built on a good ol’ Django monolith.

No Kubernetes. No gRPC. No service mesh. Just clean Python code and a team trying to move fast.

And it worked.

Even when Facebook acquired them, they kept shipping. One codebase. One deployment. One team.

You know what that meant?

• Easy debugging
• Fast development
• No ops nightmares

In many ways, it was the kind of setup most early-stage startups dream of.

The Growth Spurt

Then Instagram exploded.

Stories. Reels. Explore. Ads. Shopping. Billions of users.

Suddenly, teams were stepping on each other’s toes in the monolith. Feature A would break Feature B. Tests slowed down. CI/CD was groaning under the weight.

So, naturally…

“Let’s move to microservices.”

Because that’s what big companies do, right?

Welcome to Microservices (And Chaos)

They started splitting up the app:

• Teams got their own services.
• Code got “decoupled.”
• Things were finally “scalable.”

But slowly — almost quietly — the pain started creeping in.

• Running all services locally was a nightmare.
• Onboarding new devs? Took weeks instead of days.
• Tracking bugs? Now spanned 4 logs, 3 dashboards, and Slack pings.
• Rebuilding shared logic in different services because “it’s out of scope.”

It was like being told your dream apartment had a hot tub and home theater — but every door required a different key, and half the lights flickered randomly.

The Wake-Up Call

Instagram engineers started asking:

“Are we actually moving faster? Or just… moving?”

They realized something simple and radical:

Microservices were costing more than they were saving.

Not in money. In time, developer happiness, and productivity.

So they did something bold.

Rebuilding the Monolith (But Smarter)

No, they didn’t go back to 2011 Django. They didn’t abandon every service.

But they started pulling things back in. Reorganizing into a modular monolith.

• One deployable unit
• Strong internal boundaries
• Domain-based code separation
• Tools that understood the architecture

In other words:

One big app, but neatly folded — like a well-packed suitcase.

And guess what?

• Developers were more productive again.
• Local setup became sane.
• Testing, debugging, and deploying? Cleaner than ever.

Instagram hadn’t failed at microservices.

They just matured into an architecture that actually fit them.

So, What About You?

Take a breath if you're building something — whether it's a SaaS, a side project, or the next unicorn.

And ask yourself:

• Are you choosing microservices because it’s trendy?
• Or because it actually solves your problems?

Because here's the truth, nobody tweets:

Most apps don’t need microservices. Not yet. Maybe not ever.

Here’s What I Took From Instagram’s Journey

1. Start with a monolith. You’ll move faster and stay sane longer than you think.
2. Split services only when you must. Not because of some tech blog.
3. Optimize for developer happiness. That’s your real productivity metric.
4. Modular monoliths are a thing. Structure doesn’t need to mean “micro.”
5. Every architecture comes with pain. The trick is choosing the pain you’re actually ready to deal with.

Real Talk: Are You Overbuilding?

If your team has more services than engineers…

If onboarding feels like solving a murder mystery…

If deployments need 12 approvals and a goat sacrifice…

You might be solving problems you don’t even have yet.

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