Sandcastle is a new tool from Matt Pocock — a well-known educator in the developer world — that lets you send multiple AI coding agents off to work simultaneously, each in its own safe little box, and then collects their results when they're done.
Think of it like hiring five contractors to renovate different rooms of a house at the same time, instead of one contractor moving from room to room. When they're all done, someone coordinates the handoff so nothing clashes.
Right now, that kind of coordination required serious technical setup. Sandcastle wraps all of it into a single command.
The part that matters for business owners isn't the technical elegance — it's what it implies. If you can run ten agents in parallel instead of one in sequence, tasks that took hours could take minutes. Code reviews, content drafts, data processing pipelines — anything you'd currently queue up one by one.
The tool already supports Claude, OpenAI's Codex, and others. It's been live for days and already has 2,700 stars and a flood of contributors piling in. That kind of early energy usually means something.
If you're already using AI in your business, it's worth asking: are you running things one at a time when you could be running them in parallel? The bottleneck might not be the AI — it might be the architecture around it.
Agent — An AI that doesn't just answer questions, but takes a series of actions to complete a task on your behalf. Like the difference between asking someone what to cook versus handing them your keys and asking them to go grocery shop.
Sandbox — A contained, isolated environment where software can run without affecting anything else. Like a test kitchen that can burn down without touching the restaurant.
Parallel — Doing multiple things at the same time instead of one after the other. A chef prepping three dishes at once, not finishing one before starting the next.
Orchestration — Coordinating multiple agents or tasks so they don't conflict and their results come together cleanly. The conductor, not the musicians.