---
title: "Scaling to 1 million concurrent sandboxes in seconds"
url: https://daily.dev/posts/scaling-to-1-million-concurrent-sandboxes-in-seconds-sxsixg1ry
source_url: https://modal.com/blog/scaling-to-1-million-concurrent-sandboxes-in-seconds
type: article
source: "Modal"
published: 2026-07-16T20:15:46.083Z
updated: 2026-07-16T20:16:09.130Z
tags: ["distributed-systems"]
reading_time: 9
upvotes: 1
comments: 0
language: en
---

> ## Documentation Index
> Fetch the complete documentation index at: https://daily.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Scaling to 1 million concurrent sandboxes in seconds

**[Modal](https://daily.dev/sources/modal_labs)** · 9 min read · 1 upvotes · 0 comments

## Summary

Modal rebuilt its sandbox platform from the ground up to support 1 million concurrent sandboxes, achievable in under a minute. The new architecture eliminates central coordination bottlenecks by replacing a centralized scheduler and durable datastore with a fleet of scheduling servers using in-memory cached worker state published via Redis streams. Workers become their own source of truth, sandbox creation requires only two network hops, and all O(sandboxes) and O(nodes) operations are horizontally scalable. Kubernetes-style strong consistency was traded for performance. Median sandbox start time is under 500ms. The system is in Beta and will soon back all Modal sandbox scheduling.

## Full article

daily.dev links to this article rather than hosting it. Read it at the original source: <https://modal.com/blog/scaling-to-1-million-concurrent-sandboxes-in-seconds>

## Similar posts on daily.dev

- [Vibing at scale](https://daily.dev/posts/vibing-at-scale-x7tx5lrnn) · Modal · 1 upvotes · 0 comments
- [Product updates: VM Sandboxes, Lower latency routing, RBAC, and more](https://daily.dev/posts/product-updates-vm-sandboxes-lower-latency-routing-rbac-and-more-eu4o7sjio) · Modal · 2 upvotes · 0 comments
- [QCon London 2026: Fixing the AI Infra Scale Problem by Stuffing 1M Sandboxes in a Single Server](https://daily.dev/posts/qcon-london-2026-fixing-the-ai-infra-scale-problem-by-stuffing-1m-sandboxes-in-a-single-server-ziuvqxl43) · InfoQ · 0 upvotes · 0 comments
- [Unpacking sandbox startup latency: why started ≠ ready](https://daily.dev/posts/unpacking-sandbox-startup-latency-why-started-ready-fu4gwfwie) · Modal · 3 upvotes · 1 comments
- [SkyPilot Sandboxes: Run Agent Code on Your Own Kubernetes, at Scale](https://daily.dev/posts/skypilot-sandboxes-run-agent-code-on-your-own-kubernetes-at-scale-q6ldvrf5n) · SkyPilot · 1 upvotes · 0 comments

---

Tags: [#distributed-systems](https://daily.dev/tags/distributed-systems)

[View this post on daily.dev](https://daily.dev/posts/scaling-to-1-million-concurrent-sandboxes-in-seconds-sxsixg1ry)