Billing systems that don't double-charge. Webhooks that don't double-fire. Ledgers that refuse to go out of balance. Chazbit is a deliberately small senior engineering practice — 20 years deep, most recently the builder of a complete double-entry accounting SaaS: ledger engine, Stripe Billing + Connect, bank feeds, tax reports, the works. We take one or two engagements at a time for teams whose money-moving code needs hands that have already survived it.
// A webhook you can trust: verified, idempotent, replay-safe.
// Stripe retries. Networks duplicate. Your ledger doesn't care.
public function handle(Request $request): Response
{
$event = $this->verifier->verify($request); // signature first, always
if ($this->ledger->alreadyProcessed($event->id)) {
return response()->noContent(); // replay → no-op, no double post
}
DB::transaction(fn () =>
$this->handlers->for($event->type)->process($event)
); // the fee posts as a real journal entry: DR 5150 / CR 1050
return response()->noContent();
}Finappses is a multi-tenant, double-entry accounting SaaS — every line of it designed, built, tested, and shipped by our principal engineer — one set of hands, zero handoffs. It's the hardest audition piece we could have chosen, because accounting software has nowhere to hide: either the books balance or they don't. Click around the live demo →
| Account | Memo | Debit | Credit |
|---|---|---|---|
| 1050 Stripe Clearing | Card payment — inv #241 | 1,250.00 | |
| 5150 Processing Fees | Stripe fee | 36.55 | |
| 1200 Accounts Receivable | Invoice settled | 1,250.00 | |
| 4010 Service Revenue | Fee recognized net | 36.55 | |
| Totals — the ledger enforces this | 1,286.55 | 1,286.55 | |
If your problem isn't one of these, we'll tell you on the first call and point you at a better fit. If it is one of these, you're working with a practice that has shipped it before — recently, and end to end.
Stripe Billing, Connect, and the webhook layer underneath — built new or untangled. Subscription migrations, usage pricing, dunning, and the idempotency discipline that keeps finance from filing tickets.
Fits: SaaS teams whose billing is revenue-critical and fragile
The codebase your team is afraid of. We audit it, name the traps out loud, and modularize the monolith with DDD boundaries — the same discipline that untangled 300-app legacy migrations and label-plant ERPs.
Fits: teams shipping slower every quarter and unsure why
Double-entry cores, reconciliation engines, money movement with audit trails. Minor-unit arithmetic, immutable entries, provenance on every posted row — the parts most contractors have never had to get right.
Fits: products where the balance is the product
From embedded controllers on vehicle lifts to a platform doing eight figures a year — the common thread is software where "mostly works" was never an option.
One email or a 30-minute call. We'll ask the questions that expose the real scope — usually smaller than feared, occasionally bigger, never vague.
Deliverables, timeline, price. Fixed-scope for bounded work; weekly rate for open problems. Either way you know the number before work starts.
Working software every week — not a big reveal at the end. Code, tests, and docs land in your repo as we go. You can stop at any slice and keep everything.
The engagement ends on schedule, with a handover your team can actually run. If you want more later, we scope a new one. Nobody gets a permanent line item.
Describe the system, the pain, and the timeline. You'll get a straight answer within one business day — including "this isn't a fit," if that's the truth.
Currently booking · 1 slot open for Q4 2026or write directly: charles@chazbit.com · LinkedIn →