Lean, Budget-Friendly Metered Billing for SaaS – What Do You Use?

I’m building a SaaS product with a pay-per-use model (e.g. $1 per API request) and need to set up billing so I can start charging customers. I want a billing solution that’s quick to implement, lean, and doesn’t eat into my margins.

I know Stripe is a common choice, but building a fully custom billing system isn’t feasible for me right now. I’m hoping to find something I can drop in with minimal code and effort that covers the basics.

Here’s what I need:

Customers can: Set up and update payment methods. Track their usage during the billing period. Download invoices.

I can: View customer usage and past/upcoming invoices. Adjust pricing (e.g. volume discounts).

I’d love to hear from others who’ve tackled this. What tools or services worked for you?

Bonus points for developer-friendly, budget-conscious solutions that won’t make me regret not doing it myself!