VM Config & Persistence


CodeSandbox Repositories and Cloud Sandboxes run on microVM technology (opens in a new tab). Each branch and cloud sandbox gets its own microVM and their resources (shown below) are set to each one of these instances.

Default resources

Based on our analysis of usual resource needs, we have defined these resources as default:


But we can go higher, up to 12vCPUs, 16GB memory and 30GB storage. To upgrade to higher specs, you can ugrade to one of our Pro plans (opens in a new tab).

If you require specs that go beyond our Pro plan defaults, get in touch and our team will adjust the limits to suit your project.


Everything you save in /project is guaranteed to be persisted between reboots, hibernations and forks. Every file change outside of /project will usually be persisted, but there is a chance that those changes will be cleared.

Your project folder lives in /project/<repo-name>, your home folder lives in /project/home/<username>. Your home folder is inaccessible for other users.

If your branch has not been accessed for 31 days, we delete the contents of /project. This means that the next time you start this branch again, we will reinitialize /project by doing a fresh clone.

For any uncommitted work we make a backup. This backup is never deleted. All your uncommitted work is restored when you open a branch where the /project folder is deleted. This means that you will never lose your work, even if we delete /project after 31 days of inactivity.

Memory snapshots (which allow instant resume of VMs) will be cleaned up after 7 to 31 days of inactivity. There is no lost work from cleaning up memory snapshots.

Node Modules

The node_modules folder is globally ignored. You can override this behaviour by adding !node_modules in your own project .gitignore file. While this will add node_modules folders to git, they won't be displayed in the UI.

Environment configuration

You can configure the environment of your VM with a Dockerfile. To do this, create a file in the .codesandbox folder called Dockerfile. After you've saved the file, you should be prompted with a notification to restart the container.

Configuring NodeJS version

For example, to update NodeJS to v18, you can create a .codesandbox/Dockerfile with these contents:

FROM node:18

Docker support

CodeSandbox supports running Docker containers inside any workspace. You can learn more about our Docker support in our Docker documentation.

For a step-by-step guide, check out our tutorial Getting started with Docker