Why building billing infrastructure in-house is a trap

Building in-house billing infrastructure often seems like the right path for developers looking to maintain full control. However, what begins as a straightforward project quickly spirals into a tangled web of technical debt and operational headaches.

Years ago, at Zomato, we needed a dynamic pricing engine for food delivery. Seemed straightforward—compute fees based on distance, demand, and weather. We hacked together a quick solution. And then the real fun began.

Product wanted pricing experiments. Finance needed audit trails. Growth wanted promo overrides. Legal required compliance updates. Suddenly, that "simple" system turned into an engineering black hole.

I see the same story play out at every SaaS company trying to build billing in-house. It starts as a few scripts, some database tables, maybe a Stripe webhook or two. But within months, developers are drowning in a never-ending cycle of maintenance, firefighting, and feature requests.

What Developers End Up Building (And Rebuilding)

If you’ve built a homegrown billing system, you’ve probably had to tackle all of this:

1. Pricing Engine

• Define plans, features, and add-ons.

• Handle tiered, volume-based, and usage-based pricing.

• Support per-seat, pay-as-you-go, and custom enterprise deals.

2. Metering and Usage Tracking

• Ingest events (API calls, storage, compute time).

• Aggregate usage at different intervals (hourly, daily, monthly).

• Handle late-arriving events, retries, and data corruption.

3. Subscription Lifecycle Management

• Trial periods, upgrades, downgrades, and cancellations.

• Proration when customers change plans mid-cycle.

• Revenue recognition (because finance needs it).

4. Invoicing and Payments

• Generate invoices with correct usage details.

• Sync with Stripe, Chargebee, or other gateways.

• Handle failed payments, retries, and dunning workflows.

5. Discounts, Credits and Promotions

• One-time vs. recurring discounts.

• Account-level credits vs. feature-based credits.

• Complex edge cases: “Apply 20% off for the first 3 months unless they switch plans.”

6. Multi-Currency, Taxation, and Compliance

• Convert pricing across USD, EUR, INR, AED (without losing money in rounding).

• Apply VAT, GST, and sales tax correctly per region.

• Generate tax-compliant invoices and reports.

7. Reporting and Analytics

• Revenue breakdowns by plan, region, and cohort.

• Customer churn and expansion metrics.

• Audit logs (because someone will ask for them).

8. Internal Tooling for Sales, Support, and Finance

• A UI for sales teams to create custom quotes.

• A self-serve portal where customers can check usage and invoices.

• A support panel to refund customers, adjust limits, or fix billing errors.

At some point, you realize you’ve built an entire billing platform just to run your own SaaS business.

Why This Sucks for Developers

1. It’s Never “Done” – Pricing changes? You’re updating logic. New tax laws? You’re rewriting invoices. Every quarter, some new requirement keeps you in billing hell.

2. Hard to Maintain – Your billing code isn’t a clean microservice. It’s a mess of scripts, cron jobs, and SQL queries that nobody wants to touch.

3. Costly Bugs – A billing bug is not like a UI bug. It’s not a 404 error. It’s “we just overcharged 500 customers” or “we lost revenue for a month.”

4. Wasted Dev Bandwidth – Your best engineers should be building product features, not debugging why a Stripe webhook failed at 2 AM.

The Better Alternative

Instead of spending months (or years) wrestling with billing logic, use a platform that’s built for this. At Flexprice, we give developers a simple, flexible billing infrastructure that supports metering, pricing, and invoicing out of the box.

No more reinventing the wheel. No more spending 25% of engineering resources on something that should “just work.”

If you’re still maintaining a homegrown billing system, ask yourself—how much of your roadmap is held back because of it? Maybe it’s time to break free.