Trusted by Mistral AI, PayPal, Groq, and Synthesia with over 10,300 GitHub stars and Y Combinator backing, Lago is the open-source billing engine that handles usage-based, subscription-based, and hybrid pricing models through a single API-first platform — replacing the need to build custom billing logic or depend on opaque SaaS pricing infrastructure. Real-time event ingestion via ClickHouse processes billable events with deduplication and multiple aggregation methods including count, sum, unique count, max, and weighted sum, while graduated pricing tiers, package-based billing, and percentage-based fees model any pricing strategy from simple subscriptions to complex marketplace commission structures. Automated invoice generation calculates charges according to configurable billing cycles with grace periods, proration for mid-cycle changes, and credit note issuance for refunds and adjustments. Prepaid credits enable pay-in-advance models where customers purchase credit blocks and draw down as usage accumulates, while entitlements tie feature access directly to billing plans for automated provisioning and de-provisioning. Payment orchestration integrates natively with Stripe, Adyen, and GoCardless with automatic retry logic, dunning workflows for failed payments, and multi-gateway routing. Revenue analytics provide cross-stream visibility into MRR, usage trends, churn, and revenue drivers through dedicated API endpoints. The customer portal embeds into your application for self-service invoice access and usage monitoring. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPL-3.0 licensed.

With nearly 9,000 GitHub stars and adoption by over 60,000 companies across 100 countries, Papermark is the open-source DocSend alternative that turns document sharing into a data-rich conversation between you and your viewers. Every shared document generates page-by-page analytics showing exactly which pages capture attention, how long viewers spend on each section, where they drop off, and whether they return for a second look, with real-time notifications the moment a document is opened. Virtual data rooms support unlimited folders with drag-and-drop organization, bulk uploads, granular per-viewer permissions, dynamic watermarking that stamps each page with the viewer's identity, and NDA gating that requires agreement before access. Custom branding applies your logo, colors, and custom domain to every shared link and download page, while email verification and password protection add authentication layers. The AI Data Room Copilot lets viewers chat with uploaded documents, ask questions, and receive contextual summaries directly within the data room interface. The developer platform exposes 43 REST API operations covering data rooms, documents, folders, links, visitors, and analytics, with an MCP server for AI agent integration and a CLI for automation. Built on Next.js with TypeScript, Prisma ORM, PostgreSQL, NextAuth.js authentication, and shadcn/ui components. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPLv3 licensed.