Open-source billing engine · comparison
Kill Bill vs FeeGuard: self-hosted billing vs managed detection
Searching for a Kill Bill alternative usually means one thing: the job you hired Kill Bill for is getting done, and the job nobody owns — money silently leaving through Stripe Connect refunds, fees, disputes and conversions — is not. Here is the honest, side-by-side picture, including where Kill Bill genuinely wins.
What Kill Bill does
an open-source billing and payment engine with plugin architecture for teams owning their stack. Source: https://killbill.io.
That is real capability in its lane — and the lanes below show precisely where it ends.
Side by side: FeeGuard vs Kill Bill
Eight capabilities a Connect platform needs. No empty cells — every row states what each product actually does.
| Capability | FeeGuard | Kill Bill |
|---|---|---|
| Unreversed-transfer detection | Yes — computed on every `charge.refunded` event: proportional expectation, rounding tolerance, ratio clamping | No — engine layer. |
| Application-fee leak detection | Yes — application fees tested against reversals via Net Platform Margin; zero- and three-decimal currencies handled | No — fees untouched. |
| Dispute-loss clawback support | Yes — recoverable figure computed on `dispute.closed` (transfer remainder, fee excluded); early warning on `created`; gated automation | No — disputes outside. |
| Cross-border FX monitoring | Yes — realised rates measured against same-day currency-pair baselines; directional loss flagging beyond 0.8% | No — fX unmeasured. |
| Runs on your live Stripe Connect account today | Yes — read-only restricted key, roughly ten minutes to first findings, revocable anytime | Depends |
| Performs recovery actions | One-click manual reversals (free tier); risk-gated automation with idempotency keys on Monitor Pro | Varies |
| Evidence & audit trail | Append-only trail on every action; finding-level evidence ids exportable as CSV | Varies |
| Pricing model | Detection free forever · success fee 20% of first $50k recovered, 15% above · no results, no fee | Open source |
Where Kill Bill genuinely wins
- — True code ownership and extensibility.
- — Mature plugin ecosystem for billing customisation.
Why platforms choose FeeGuard over Kill Bill
- Purpose-built for the leak. All four silent-loss vectors — unreversed transfers, kept fees, uncovered dispute losses, FX drag — are native detectors, not features imagined onto another product.
- Free before you pay anyone. Detection and the 90-day lookback cost nothing — measure your stranded dollars before committing to any vendor, including us.
- Ten-minute, read-only setup. One restricted key you create and revoke; no migration, no seller re-onboarding, no payment-path changes.
- Pay-for-results recovery. 20% of the first $50k recovered, 15% above — versus subscriptions, retainers and per-alert fees that bill regardless of outcomes.
- Evidence-grade trail. Append-only logs with finding-level arithmetic — ready for controllers, auditors and diligence teams.
Bottom line
Self-hosting is control over code, not immunity from defaults — your refund paths are yours, including their correctness. If your problem lives in open-source billing engine, Kill Bill deserves its reputation. If your problem is a platform balance lower than your ledger predicts — refunds succeeding while transfers never come home — that problem has exactly one purpose-built answer, and you are reading it. Run the free audit; the number settles the debate faster than any comparison page can.
Common questions
Could we build a Kill Bill detector plugin?
Possibly — price the ongoing maintenance against adoption before deciding; that comparison is the whole decision.
Is FeeGuard a better choice than Kill Bill?
For open-source billing engine, Kill Bill is the specialist and we say so plainly. For detecting and recovering silent Stripe Connect losses — the four vectors above — FeeGuard is purpose-built and Kill Bill does not perform that function. Most platforms comparing the two are feeling the second problem.
Can we run Kill Bill and FeeGuard together?
Yes, commonly. They operate on different objects and different events; neither conflicts with the other’s workflow.
What does switching cost us?
Nothing upfront: read-only key, ten-minute setup, free detection. Recovery carries a success fee only on confirmed dollars — so trying FeeGuard risks no budget at all.