From the article:

celld is an open-source daemon that runs Cloudflare Workers and Durable Objects on your own machines. Each object is its own SQLite database, addressed by name and replicated to an S3-compatible bucket you own; nodes coordinate through that bucket alone, with no control plane or consensus. Because every object is its own small database, applications shard by construction — the contention and blast-radius failures of one shared database are designed out, not managed. Idle cells hibernate to nearly nothing. Learn more at celld.dev or read the documentation.