Knock vs building billing in-house
Building billing looks like a weekend. Maintaining it is a job.
Engineers often start by building billing themselves. The first version, a table of subscriptions and a cron job, is quick. The long tail is what costs: month ends, retries without double billing, proration, tax, refunds, access control, a customer view and years of maintenance.
Feature matrix
| Capability | Building billing in-house | Knock |
|---|---|---|
| Time to first invoice | Days to weeks | An hour to import and configure |
| Month-end and leap-day dates | You find them in production | Calendar dates with month-end clamping |
| Idempotent generation | You design and test it | Built in |
| Tax rules | You model and maintain them | Tax rules applied per line |
| Roles and customer portal | More screens to build and secure | Admin, staff and customer roles and a portal |
| Custom pricing logic | Unlimited | Plans, variants, minimum quantities, discounts. Beyond that, not supported |
| Data model ownership | Fully yours | Hosted in the deployment you run. No documented public API or integrations today |
| Ongoing maintenance | Yours, forever | Yours if you self-host it, since it is a hackathon project |
| Production maturity | As good as your team makes it | Early. No audit or support guarantees |
Who each fits
Building billing in-house fits when
- Billing is your core product or has truly unusual rules
- You need deep integration with your own systems
- You have engineers to keep it correct for years
Knock fits when
- Billing is a necessary chore, not your product
- You want the lifecycle and portal without building them
- You are validating before committing engineering time
The honest take
Knock is early. For a production business at scale, a mature vendor or a carefully built in-house system is likely the better long-term choice. Knock is a good fit for learning, prototypes and small operations, and its approach to idempotent generation and per-line tax is a reasonable reference if you do build your own.
Migration steps
- List the billing rules your code enforces today, including the odd ones
- Check whether plans, variants, discounts and taxes can express them
- Export customers and subscriptions to CSV, then import customers
- Recreate plans, then subscriptions with correct next billing dates
- Run both systems side by side for one cycle and compare invoice totals
- Retire the old cron job only after the totals match
Try Knock on a few customers
Import a handful, create a plan and run a dry run of billing. It is free to try.
Get started free