Billing
4 open source tools compared. Sorted by stars. Scroll down for our analysis.
| Tool | Stars | Velocity | Score |
|---|---|---|---|
 hyperswitch Open source, composable payments platform | PCI compliant | SaaS and Self-host options | Enables connectivity to multiple payment, payout, fraud, vault and tokenization providers | Uplifts authorization with intelligent routing and revenue recovery | Reduce payment processing costs with cost observability | Reduces payment ops with reconciliation | 43.3k | +56/wk | 92 |
 Lago Open Source Metering and Usage Based Billing. | 10.2k | +31/wk | 76 |
 Kill Bill Open-source subscription billing platform | 5.6k | +11/wk | 82 |
 New Expensify Welcome to New Expensify: a complete re-imagination of financial collaboration, centered around chat. Help us build the next generation of Expensify by sharing feedback and contributing to the code. | 4.9k | +6/wk | 80 |
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Our Analysis
Hyperswitch sits between your app and payment processors like Stripe, Adyen, and PayPal, routing each transaction to whichever is cheapest or most likely to succeed. Juspay built it after processing billions of transactions and open sourced the core in Rust under Apache 2.0. One API, many processors, no rewrite when you add or drop one. Self-hosting the Community Edition is real infrastructure: the router, Postgres, Redis, and a control center UI, plus the PCI scope questions that arrive the moment card data flows through systems you operate. This is a payments team tool, not a weekend deploy. Single-processor startups don't need it; Stripe alone is simpler than Stripe behind a switch. It earns its keep when you juggle multiple processors for fees, geographic coverage, or failover. Solo and small teams: skip. Companies at real volume: smart routing and retry logic can recover a measurable slice of revenue. Enterprise Edition and Cloud exist when you'd rather pay Juspay to run it. The catch: it orchestrates payments, it doesn't process them. You still need contracts with the underlying processors, and advanced features like revenue recovery and reconciliation are paid add-ons even on top of the open core.
Lago handles the billing plumbing that makes SaaS companies tear their hair out: usage metering, subscription management, invoicing, payment orchestration, and revenue analytics. If you're building usage-based pricing (per API call, per seat, per compute hour), this is the open source engine that competes with Chargebee and Stripe Billing. Self-hosting runs on Docker Compose with PostgreSQL. The API and frontend are separate services, which adds some initial complexity but keeps things modular. Event ingestion handles real-time usage tracking, aggregation rules turn raw events into billable metrics, and the invoicing engine generates PDFs. Integrations with NetSuite, Xero, Salesforce, and tax providers like Avalara cover the accounting side. Solo founders can run the full billing stack for free. Growing startups avoid Stripe Billing's percentage-of-revenue pricing by self-hosting. Enterprise teams get Lago Cloud for managed infrastructure with pay-as-you-go pricing. The catch: AGPL license. If you embed Lago into a SaaS product, the copyleft clause may require open-sourcing your application. Many companies end up on the paid cloud plan specifically to avoid that legal exposure.