ScratchRun

Name: ScratchRun
Author: ar-blues

by ar-bluesversion 0.1.1i★ –iRuns on your computer

Registry namedev.scratchrun/mcp

Install

Overview

Description from the maker (original English)

Ephemeral MicroVM-isolated code execution for AI agents. Fresh VM per call, hard-purged after.

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

User voiceiNo reviews yetReviews open together with accounts in a later step
Our basic checksi1 of 1 passedChecked from public information; code not scanned yet
UsageiNot measured yet★ –

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

Connection: Runs on your computer
Transport: stdio
Category: Other
You need to fill in: SCRATCHRUN_API_KEY

Install

Pick the AI app you use, then copy the settings.

Before you install

Basic checks: 1 of 1 passed
Runs on your computer with your user’s permissions (files, network, apps).
You fill in yourself: SCRATCHRUN_API_KEY

Values marked secret are keys to your account. Never share them or paste them into a chat.

You need

npmNode.js installed (for the npx command)

Which app do you use?

ClaudeClaude CodeCursorVS CodeChatGPT

Pick your app above. We remember it, so next time the button says “Install in …”.

Open Claude Desktop → Settings → Developer → Edit Config, and paste this into claude_desktop_config.json

{
  "mcpServers": {
    "scratchrun": {
      "command": "npx",
      "args": [
        "-y",
        "@scratchrun/mcp-server"
      ],
      "env": {
        "SCRATCHRUN_API_KEY": "your-value"
      }
    }
  }
}

Run this in your terminal

claude mcp add scratchrun --env SCRATCHRUN_API_KEY=your-value -- npx -y @scratchrun/mcp-server

Fill in the empty values before running it.

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

{
  "mcpServers": {
    "scratchrun": {
      "command": "npx",
      "args": [
        "-y",
        "@scratchrun/mcp-server"
      ],
      "env": {
        "SCRATCHRUN_API_KEY": "your-value"
      }
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

{
  "servers": {
    "scratchrun": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "@scratchrun/mcp-server"
      ],
      "env": {
        "SCRATCHRUN_API_KEY": "your-value"
      }
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

This one runs on your computer, and ChatGPT can only connect to servers on the internet. Pick another app.

Your choice stays on this device in a cookie; no account needed.

Values you fill in

SCRATCHRUN_API_KEY secret required env
ScratchRun API key — get one at https://scratchrun.dev

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

Runs on your computer; the tool list appears in your AI app after you install it.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 7, 2026

✓ Pass
Maker matches the repo
The registry name was verified against the domain scratchrun.dev (the registry checks domain ownership)
… Not checked yet
Still maintained
We have not read this repo from GitHub yet
… Not checked yet
Has a licence
We have not read this repo from GitHub yet
– Not applicable
Endpoint responds
This one runs on your computer; there is no internet endpoint
– Not applicable
Sign-in with OAuth
Runs on your computer and uses local settings instead
… Not checked yet
No hidden instructions in tool descriptions
Runs on your computer; we can only read tool lists from internet endpoints

Compared with others in Otheri

More stars than 0% of the other 32537 servers in this category
Published to the registry more recently than 21% of the other 32537 servers in this category
Basic checks equal to or better than 100% of the other 32537 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is ScratchRun safe?

It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

You need to fill in: SCRATCHRUN_API_KEY

Does it run on my computer or in the cloud?

It runs on your computer. Your AI app starts it when needed, and data does not pass through the maker’s servers (unless it calls an online service itself).

Is it still maintained?

The GitHub repo last changed –, and the latest version (0.1.1) reached the registry 3 months ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need Node.js on your computer.

What can I use instead?

In the same category: Spec Driven Development, Remote Desktop Commander, TF Rooms

Alternatives

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Reading a card:★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi

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Runs on your computer★ 440MITUpdated 14 months ago

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README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

@scratchrun/mcp-server

MCP server for ScratchRun — ephemeral, MicroVM-isolated code execution for AI agents.

Each call runs in a fresh hardware-isolated MicroVM. The VM is hard-purged after execution. No state, no files, nothing persists between calls.

Install

Add to your claude_desktop_config.json:

"mcpServers": { "scratchrun": { "command": "npx", "args": ["-y", "@scratchrun/mcp-server"], "env": { "SCRATCHRUN_API_KEY": "sr_live_your_key_here" } } } }

Get an API key at scratchrun.dev.

Tool: `scratchrun_exec`

Executes code in an ephemeral sandbox and returns stdout, stderr, exit code, and any output files.

Parameters:

Parameter	Type	Required	Description
`runtime`	`python3.12` \	`python3.11` \	`node20` \	`bash`	yes	Runtime to use
`code`	string	yes	Code to execute
`timeout_ms`	integer	no	Timeout in ms (default 10000, max 30000)
`memory_mb`	integer	no	Memory limit in MB (default 256, max 512)
`env`	object	no	Environment variables — use for secrets, not code strings
`files`	object	no	Files to write before execution (path → content)
`return_files`	string[]	no	File paths to capture after execution (returned as base64)

Example — run Python and return a chart:

"runtime": "python3.12", "code": "import matplotlib.pyplot as plt\nimport numpy as np\nx = np.linspace(0, 10, 100)\nplt.plot(x, np.sin(x))\nplt.savefig('/tmp/plot.png')", "return_files": ["/tmp/plot.png"] }

Output files are returned as base64. Image files (PNG, JPG, SVG) are returned as MCP image content blocks and render inline in Claude.

Isolation

Hardware-virtualized MicroVM per execution (own kernel, not a shared-kernel container)
TerminateMicroVM called unconditionally after every run — VM destroyed, never reused
RFC 1918 + cloud metadata (169.254.x.x) always blocked at the network layer
Read-only system filesystem via OverlayFS; /tmp is RAM-backed and gone with the VM

Latency

~400ms median (warm pool). 2–8s cold start if the pool is empty.

License

MIT

ScratchRun

Overview

PopNx MCP’s three pillars

What you can do with it

Install

Before you install

Values you fill in

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Compared with others in Otheri

Common questions

Alternatives

Spec Driven Development

Remote Desktop Commander

TF Rooms

README from the maker

@scratchrun/mcp-server

Install

Tool: scratchrun_exec

Isolation

Latency

License

Tool: `scratchrun_exec`