Instant vs Libretto

Instant 1.0 is a backend-as-a-service specifically designed for the era of AI-coded applications. Instead of building REST APIs, developers (and the AI agents coding for them) get a real-time database directly in the frontend — with built-in auth, permissions, storage, and payments bundled in. The API surface is deliberately minimal enough for LLMs to understand without large context windows. The key differentiation is agent-friendliness: Instant is fully operable via CLI, supports undo for destructive actions (critical when LLM-generated code makes mistakes), and includes a Google Zanzibar-inspired permissions system out of the box. YC-backed and already in production at multiple startups including Eden, HeroUI, and Prism, it has validation beyond prototype use cases. With AI agents increasingly writing the first draft of every app, backends that LLMs can reliably reason about become a competitive moat. Instant's bet is that the next generation of infrastructure needs to be designed for machines to operate, not just humans to configure. The HN thread had strong positive response with nuanced debate on Firebase comparisons.

Libretto is an open-source browser automation toolkit built by Saffron Health to solve a critical problem with AI-driven web agents: non-determinism. Standard agent-controlled browsers using Playwright or Puppeteer routinely fail 20-30% of the time on production workflows because they rely on LLM judgment for timing and element selection. Libretto replaces that with a record-replay system that captures precise interaction timing and DOM fingerprints, achieving a reported 95% success rate on identical workflows. The library works by recording a "golden path" of a browser session — capturing not just actions but the exact CSS selectors, visual context, and timing windows during which those actions are valid. On replay, it verifies each step against expected page state before proceeding, and falls back to an LLM-assisted recovery mode when pages drift (e.g., after a UI update). Saffron Health built it to maintain integrations with EHR portals that change frequently and where failure has compliance consequences. Saffron open-sourced Libretto after using it internally for 18 months across 40+ healthcare software integrations. The HN thread highlighted the appeal for fintech, legal, and healthcare automation where reliability, not just capability, is the product. The toolkit targets TypeScript/Node.js environments and integrates cleanly with existing Playwright infrastructure.