ForeverVM

What is ForeverVM about?

ForeverVM provides an API and CLI for creating machines—isolated, stateful Python processes—that can execute arbitrary code one instruction at a time. Machines are automatically swapped to disk when idle and re‑hydrated on demand, enabling them to run "forever" without manual management.

How to use ForeverVM?

1. Obtain an API token – contact paul@jamsocket.com if you don’t have one.
2. Login via the CLI: npx forevervm login
3. Start a REPL: npx forevervm repl (creates a new machine) or npx forevervm repl <machine_name> to reconnect.
4. List machines: npx forevervm machine list
5. Programmatically – install the SDK (npm i @forevervm/sdk) and use the ForeverVM class to create machines, execute code, stream output, and filter by tags or memory limits.

import { ForeverVM } from '@forevervm/sdk'

const fvm = new ForeverVM({ token: process.env.FOREVERVM_TOKEN })
const repl = fvm.repl()
const result = await repl.exec('4 + 4')
console.log('result:', await result.result)

Key Features of ForeverVM

• Stateful machines that retain memory and variables across instructions.
• Automatic persistence: idle machines are swapped to disk and re‑loaded on demand.
• Tagging system: create and filter machines by custom tags.
• Memory limits: specify memory_mb per machine to control resource usage.
• Full CLI for quick REPL access, machine management, and login.
• TypeScript SDK with promise‑based execution and streamed stdout/stderr.

Use Cases of ForeverVM

• Running AI‑generated snippets safely in an isolated environment.
• Long‑running data‑processing jobs that need to maintain state.
• Interactive teaching labs where each student gets a persistent Python session.
• Debugging or prototyping code without installing a local interpreter.
• Backend services that require on‑demand execution of user‑provided scripts.

FAQ

Q: Do I need to manually stop a machine? A: No. Machines automatically persist to disk when idle and are cleaned up according to the service’s retention policy.

Q: How is security enforced? A: Each machine runs in a sandbox isolated from the host system, and execution is restricted to pure Python code without filesystem or network access.

Q: Can I set resource limits? A: Yes. Use the memory_mb field when creating a machine to cap its memory usage.

Q: What languages are supported? A: Currently only Python is supported.

Q: How do I authenticate the SDK? A: Export the token as FOREVERVM_TOKEN or pass it directly when constructing ForeverVM.

foreverVM

repo	version
cli
sdk

foreverVM provides an API for running arbitrary, stateful Python code securely.

The core concepts in foreverVM are machines and instructions.

Machines represent a stateful Python process. You interact with a machine by running instructions (Python statements and expressions) on it, and receiving the results. A machine processes one instruction at a time.

Getting started

You will need an API token (if you need one, reach out to paul@jamsocket.com).

The easiest way to try out foreverVM is using the CLI. First, you will need to log in:

npx forevervm login

Once logged in, you can open a REPL interface with a new machine:

npx forevervm repl

When foreverVM starts your machine, it gives it an ID that you can later use to reconnect to it. You can reconnect to a machine like this:

npx forevervm repl [machine_name]

You can list your machines (in reverse order of creation) like this:

npx forevervm machine list

You don't need to terminate machines -- foreverVM will automatically swap them from memory to disk when they are idle, and then automatically swap them back when needed. This is what allows foreverVM to run repls “forever”.

Using the API

import { ForeverVM } from '@forevervm/sdk'

const token = process.env.FOREVERVM_TOKEN
if (!token) {
  throw new Error('FOREVERVM_TOKEN is not set')
}

// Initialize foreverVM
const fvm = new ForeverVM({ token })

// Connect to a new machine.
const repl = fvm.repl()

// Execute some code
let execResult = repl.exec('4 + 4')

// Get the result
console.log('result:', await execResult.result)

// We can also print stdout and stderr
execResult = repl.exec('for i in range(10):\n  print(i)')

for await (const output of execResult.output) {
  console.log(output.stream, output.data)
}

process.exit(0)

Working with Tags

You can create machines with tags and filter machines by tags:

import { ForeverVM } from '@forevervm/sdk'

const fvm = new ForeverVM({ token: process.env.FOREVERVM_TOKEN })

// Create a machine with tags
const machineResponse = await fvm.createMachine({
  tags: { 
    env: 'production', 
    owner: 'user123',
    project: 'demo'
  }
})

// List machines filtered by tags
const productionMachines = await fvm.listMachines({
  tags: { env: 'production' }
})

Memory Limits

You can create machines with memory limits by specifying the memory size in megabytes:

// Create a machine with 512MB memory limit
const machineResponse = await fvm.createMachine({
  memory_mb: 512,
})