Stripe is live. The hard part starts now: metering, proration, dunning, tax, reconciliation.

Billing engineering, not "we'll install Stripe." Webhook reliability, metering, proration, dunning, tax, multi-currency, reconciliation. For teams already live on Stripe who need it right.

Talk to a billing engineer See billing work

Engagement scope · Draft

#BILL-2026-001

Senior Billing Engineering
Webhook reliability harness
Usage-based cost model
Migration playbook (WCS to Stripe to Zoho)

TotalProduction-grade, scoped on intake

Numbers from the work

40K+

Subscriptions generated on PlusHeat (Zoho)

$5M

Handled across billing implementations

$4.42

Per-user/month modelled cost (Mux baseline)

50%

Off-for-3-months promo running cleanly

What you get

Six engagements. Each one a separate billing discipline.

Stripe Billing builds

Checkout, Customer Portal, Tax, Connect for marketplaces. Real plan/coupon/promo logic, not a Stripe Checkout drop-in.

Usage-based & metered billing

Including modelling the unit economics before the billing schema is locked. Per-user, per-event, per-minute, per-MB, whichever the product actually charges on.

Subscription migrations

Stripe, Zoho, WCS, Chargebee, Recurly. Renewal cadence preserved, payment methods migrated where the gateway permits, proration state honoured.

Webhook reliability

Idempotency keys, replay handling, retry, dead-letter queues, audit logs. The boring part that costs the most money when it breaks.

Dunning engineering

Smart retry windows, customer-friendly recovery emails, store-credit application, fallback charge methods. Recovers the renewals others write off.

Reconciliation

Stripe events to application database to accounting (Xero / QuickBooks / Zoho Books). End-of-month closes in hours, not days.

Per-user cost curve

Three pricing models. One curve tells you which one you actually have.

Modelled per-user cost across 0 to 10,000 users for flat-fee, tiered, and usage-based structures. The Mux-derived usage curve plateaus at $4.42/user/month at scale, unrecoverable if your pricing was set assuming flat.

Flat fee

$7/user/month baseline, declining slightly with scale.

Under-charges past 2,000 users.

Tiered

Step function: $8 under 1K, $5.50 to 5K, $4.20 beyond.

Over-charges between 500 and 1,000.

Usage-based (Mux)

Grows then flattens after the free tier exhausts.

Stabilises only past 5,000 users, at $4.42/user/month.

Inflection: flat-fee under-charges past 2,000 users; tiered over-charges between 500 and 1,000; usage-based stabilises only past 5,000.

Evidence

Three engagements. Three different billing disciplines.

Combinatorial matrix · 40K+ subs

PlusHeat: Zoho orchestration

Plan x homeowner/landlord x call-out excess x monthly/annual x add-ons x promo x DD/card. Orchestration layer between marketing site, customer, and Zoho: source-of-truth discipline, idempotent webhook handling, promo stacking that doesn't leak revenue.

Store credit · SQL gotchas

INSPIRELLE: store credit recovery

Mapping coupon amounts back to renewal totals via raw SQL: wp_postmeta where post_title = coupon_code joined to meta_key = 'coupon_amount'. Resolved MySQL collation errors (#1267, illegal mix of collations) on the join. Real engineering, not a plugin install.

Cost modelling first

Player Profile Hub: Mux economics

Modelled $0.003/min storage, $0.0008/min delivery blended, 100K free minutes/month, 75% watch-rate cap, 50/50 720p/1080p blend (0.9 factor). Baseline: $4.42/user/month at 10 views/min. Delivered as Word report plus interactive React calculator on Vite + React 18 + Tailwind.

Pair this with WooCommerce Subscriptions (the recovery layer underneath), SaaS web app development, and API and integration work for the webhook and reconciliation infrastructure.

Good fit if

When billing is real engineering

Teams with Stripe live who need the next layer: metering, proration, multi-currency, reconciliation
Products with usage-based pricing where the unit economics need modelling before billing ships
Operators migrating between billing platforms without losing renewal cadence
Engineering teams who want webhook reliability done by someone who has shipped it three times

Probably not a fit

When the Stripe docs are enough

First-time Stripe Checkout install with no subscription, no metering, no tax complexity. Read the Stripe docs
Stores under $100K ARR where the engineering cost outpaces the recovered revenue
Teams looking for someone to copy-paste the Stripe quickstart

Tools we use

Stripe by default. The others when the buyer made that decision already.

Billing: Stripe Billing · Customer Portal · Tax · Connect · Issuing where relevant
Alt billing: Zoho Subscriptions · Chargebee · Recurly · WooCommerce Subscriptions
Reliability: Idempotency keys · replay queue · DLQ · structured audit log
Accounting: Xero · QuickBooks · Zoho Books reconciliation

If Stripe is live and something's off

Bring the failure mode. We'll diagnose inside a call.

Talk to a billing engineer hello@appycodes.com