Inngest JS is a TypeScript SDK for building reliable, event-driven applications with durable execution. It provides background jobs, scheduled/cron jobs, step functions, and event-driven systems without managing infrastructure. The SDK works across multiple runtimes (Node.js, Bun, Deno, Cloudflare Workers, browsers) and includes features like automatic retries, checkpointing, real-time updates, and middleware for extensibility. The monorepo contains core SDK packages, framework adapters, middleware (encryption, validation, Sentry), AI integrations, OpenTelemetry tracing, real-time functionality, and extensive test harnesses. Examples demonstrate integration with popular frameworks like Next.js, Express, SvelteKit, Remix, and NestJS.