What CoinHaus Taught Me — Running an App Through Market Cycles

An App That Breathes With the Market

CoinHaus is an unusual app to maintain. When crypto markets are hot, traffic explodes. When markets go cold, things get quiet.

In the 2021 bull run, daily active users surged. During the 2022 downturn, they dropped by more than half. Living through those cycles taught me things about market-dependent apps that you can't learn from any tutorial.

Infrastructure Elasticity Is Non-Negotiable

During the bull run, the traffic spike overwhelmed the server. Thousands of WebSocket connections came in simultaneously and the instance ran out of memory. The app went down at the worst possible time — when users needed it most.

I migrated the WebSocket server to Cloud Run, which scales automatically based on demand. Firebase already handled scaling on its side. After that, traffic spikes became problems the infrastructure dealt with rather than incidents I had to respond to manually.

Drawing the Free vs. Paid Line

CoinHaus monetizes with a subscription for premium features. The hard part: deciding which features go behind the paywall.

Too much behind the paywall and users leave. Too little and there's no revenue. After a lot of trial and error, I settled on keeping basic price tracking and community access free, while gating real-time price alerts and portfolio return tracking behind the premium tier.

That split worked. The free experience is genuinely useful, which keeps users around. The premium features are things active investors actually need, which justifies the subscription.

Regulatory Uncertainty

Crypto apps in Korea face unique challenges that general apps don't. There are restrictions on advertising crypto-related content, and App Store reviews for finance-adjacent apps run stricter than average. Updates that would sail through review for a different category sometimes take extra rounds for CoinHaus.

Exchange API policies also change without much warning. One day an endpoint gets deprecated, price data for one exchange stops updating, and users start writing reviews about it before I've even seen the change notice. Monitoring exchange developer channels and changelogs became a regular part of the job.

When a Cycle Ends

CoinHaus is technically the most complex app I've built — real-time data, WebSocket connections, a community layer, and a payment system, all running together.

As the 2021 bull run ended and the market cooled, active development wound down naturally. The app still runs, but it hasn't had a meaningful update since then.

If the market heats up again, I'll probably revisit it. I've kept notes on what I'd do differently. Until then, it sits as a working record of a specific moment in the crypto cycle.