S3Box

A local S3 server for your Mac.

Start it from the menu bar. Point your app at localhost. Your files stay on your own disk.

Buy a license · $9 Download for macOS

macOS 14 or later · Apple silicon and Intel · One-time payment

S3Box icon: an open orange box

Let your AI tools use it

  • Claude
  • Cursor
  • Codex
  • Copilot
  • Gemini
  • Antigravity

S3Box includes a standard MCP server that runs as a local command. Add it to any app that supports MCP. For Claude Code, the app gives you the exact command to copy.

claude mcp add s3box -- "/Applications/S3Box.app/Contents/MacOS/s3box-mcp"

Works with the tools you have

# S3Box runs on localhost:9000
export AWS_ACCESS_KEY_ID=s3box
export AWS_SECRET_ACCESS_KEY=s3box-secret
export AWS_DEFAULT_REGION=us-east-1

aws --endpoint-url http://localhost:9000 s3 mb s3://my-bucket
aws --endpoint-url http://localhost:9000 s3 cp photo.jpg s3://my-bucket/
aws --endpoint-url http://localhost:9000 s3 ls s3://my-bucket/

Any S3 SDK works. Use path-style access and point it at your local endpoint.

What you get

Lives in the menu bar

Start, stop, and copy the endpoint in one click. It can start at login.

Real S3 requests

Signed requests, presigned URLs, buckets, and objects. The calls your app already makes.

A native file browser

Browse folders, drag files in to upload, download, delete, and copy a temporary link.

Accounts and buckets

Make keys for each app. Limit an account to some buckets, or make it read-only.

Works with your AI tools

An MCP server lets Claude, Cursor, Codex, and more list, read, and upload files. Turn it off, or make it read-only.

Updates itself

New versions are checked, verified, and installed from the app.

Pricing

$9

Pay once. No subscription.

Buy a license
  • One license covers 3 Macs
  • 1 year of updates
  • The version you have keeps working after that
  • Free up a Mac any time in the license portal

Questions

What does it support?

Create and list buckets, upload, download, head, and delete objects, list with prefixes and folders, and presigned URLs. Requests are signed with SigV4. It does not do multipart upload, versioning, or ACLs yet.

Is it for production?

No. S3Box is for local development and testing, so you can build against S3 without a cloud account or a network.

Where are my files?

In a folder on your Mac. You choose the folder in the Server settings. Nothing is uploaded anywhere.

What does the app contact over the internet?

The license server, to check your key, and GitHub, to look for new versions. Your files and keys stay on your Mac.

What happens after the first year?

Your version keeps working. New versions need a renewed license.

What do I need to run it?

A Mac with macOS 14 or later. Apple silicon and Intel are both supported.