Lago is the leading open-source billing engine designed to handle the complexity of usage-based and hybrid billing models that traditional SaaS billing tools struggle to support. Architected as an API-first solution, Lago decouples the billing logic from the payment gateway, allowing engineering teams to implement sophisticated metering, rating, and invoicing workflows without vendor lock-in. By 2026, Lago has positioned itself as the industry standard for AI and infrastructure companies that require high-throughput event processing (metering) to bill users based on tokens, compute time, or API calls. Its technical stack utilizes a robust event-driven architecture, typically deployed via Docker, leveraging PostgreSQL for persistence and Redis for high-speed event ingestion. The platform provides a bridge between complex usage data and financial compliance, offering automated tax calculation, multi-currency support, and seamless synchronization with ERP systems. It is the preferred choice for Lead AI Architects looking to build scalable monetization layers while maintaining full sovereignty over their financial data and avoiding the 'Stripe tax' on high-volume transactions.
An asynchronous event processing system capable of handling thousands of events per second for real-time rating.
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Supports combining flat-fee subscriptions with multiple usage-based billable metrics in a single invoice.
Programmatic control over trial durations and payment grace periods via API.
Abstracts the payment layer, allowing routing of payments to different gateways (Stripe, Adyen) based on geography.
Enables recalculation of invoices if usage data is corrected post-event ingestion.
Native hooks for TaxJar and Anrok to automate global VAT and Sales Tax compliance.
Built-in logic for customer wallets where users can pre-purchase 'credits' consumed by usage.
Charging customers per 1k tokens across different LLM models with varying prices.
Registry Updated:2/7/2026
A marketplace needs to take a 2% cut of every transaction + $0.30 fixed fee.
Billing based on CPU/RAM hours and storage GBs.