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Lago

Open-source billing built around usage events rather than pre-aggregated totals — the natural philosophical partner for open-source analytics.

What it is

A YC-backed open-source billing platform focused on usage-based and hybrid pricing. You define billable metrics (api_calls, messages_sent, storage_gb) and stream usage events; Lago aggregates them into invoices from plan definitions. Built on Ruby on Rails, PostgreSQL, Redis and Sidekiq. Notable users include PayPal, Synthesia and Mistral.ai.

Key facts
Category Billing layer (open core)
Licence Apache 2.0 core; premium features gated behind Cloud
Deployment Self-hosted (free) or Lago Cloud
Usage metering Event-based, up to ~15,000 events/sec
Aggregations count, sum, max, unique count
Data access Direct database + API + webhooks
Payment processors Agnostic — Stripe, GoCardless, Adyen, custom
Compliance SOC 2 Type 2
Adoption (as of March 2026) 7K+ GitHub stars

Strengths

  • Open-source core with direct database access
  • Event-based architecture preserves granular usage data
  • Payment-processor agnostic — no Stripe lock-in
  • No percentage-of-revenue pricing

Limitations

  • Younger than Stripe and Kill Bill; less battle-tested at extreme scale
  • Self-hosting requires DevOps capability
  • Some advanced features gated behind paid Cloud
  • Documentation still maturing

Relevance to Tidemill

Lago is Tidemill's beachhead market and the strongest argument for the project's existence: Lago users have no dedicated open-source analytics companion today, and are already philosophically aligned. See product positioning.

Technically it is the motivating case for Tidemill's same-database mode — analytics queries Lago's PostgreSQL directly, with zero ETL and no Kafka. That is a fundamentally different integration shape from the Stripe ingestion path, and the reason DatabaseConnector exists alongside WebhookConnector in connectors.

Because raw usage events are available rather than pre-aggregated totals, Lago can in principle support more exact usage revenue than Stripe's trailing-average approximation.

Status: P1, not yet implemented. tidemill/connectors/lago.py is planned; only Stripe and Chargebee ship today.

Sources