CAPSEM

The fastest way to ship with AI securely.

Open in

Claude Code Codex Cursor
View setup prompt
Installation guide ↗

Download Capsem

Choose your platform

Release details ↗
curl -fsSL https://capsem.org/install.sh | sh

Install Capsem, build and preview a website in an AGY VM, explicitly create a separate Email productivity VM through the TUI, then open the GUI and create four more sessions. Type a different prompt in each tab while earlier agents keep working independently in their own VMs.

Your favorite AIs.

Switch anytime — or use all of them in parallel.

  • Claude Code

    Claude Code
    View setup prompt
    Installation guide ↗
  • Codex

    Codex
    View setup prompt
    Installation guide ↗
  • Gemini CLI

    Paste into your agent to get started.

    View setup prompt
    Installation guide ↗
  • Antigravity

    Paste into your agent to get started.

    View setup prompt
    Installation guide ↗
  • Ollama

    Paste into your agent to get started.

    View setup prompt
    Installation guide ↗

Everything you need, out of the box.

Code

  • Python
  • Node.js
  • NumPy
  • pandas
  • SciPy
  • scikit-learn
  • Matplotlib
  • pytest

Tools

  • Git
  • GitHub CLI
  • uv
  • tmux
  • curl
  • FastMCP

MCP tools

  • fetch_http
  • grep_http
  • http_headers

Make it yours. Your tools. Your MCP servers. Your own images.

Build your environment

Built to help you move fast.

Nothing slows you down.

1.2s

Launch an environment

3kreq/s

Network that keeps up

60ms

Duplicate your environment

Recorded benchmarks · May–June 2026
Measurement details

Environment launch and duplication: macOS ARM64, June 2026, means of 3 runs (1,132.2 ms and 55.9 ms), rounded conservatively to 1.2 s and 60 ms. Network: historical May 2026 proxy baseline, 3,042.6 requests/s at 10 concurrent requests over 10 seconds. These isolated benchmarks do not measure agent readiness or external network speed. Results vary by hardware and workload.

Secure by default
so you can focus on your goal.

Isolation, protected credentials, and checks on what goes in and out.

Legend
  • Components, inputs and outputs
    No host-permission level assigned by this diagram.
  • Control and processing
    Components or stages that manage and process operations.
  • Host-held credentials
    Credential material stays outside the VM.
  • Per-VM ownership
    Dashed boundary groups components assigned to one VM.
  • VM hardware boundary
    Separates the Linux VM and its workload from host processes.
FromConnectionTo
Isolated Linux VMusesSecurity engine — — Access rules — Privacy scanning — Credential interposition
Credentials — Kept outside the VMuses · controlSecurity engine — — Access rules — Privacy scanning — Credential interposition
Security engine — — Access rules — Privacy scanning — Credential interpositionusesAI models
Security engine — — Access rules — Privacy scanning — Credential interpositionusesMCP tools
Security engine — — Access rules — Privacy scanning — Credential interpositionusesWeb & APIs
Security engine — — Access rules — Privacy scanning — Credential interpositionuses · controlLogging & reporting — Activity. Decisions. Evidence.
Explore the security architecture

Stay in control.

See everything.

Every action, request, and decision is recorded.

Interactions
Tool calltrace a8f2 · turn 1
fetch_httpcapsemallow

Arguments

{"url":"https://example.com"}

Observed response

200 OK · text/html · 2.4 KB

Model response09:41:04

Full control.

Seamlessly set boundaries at the semantic level.

CEL rules
Restrict MCP toolsdeny
mcp.tool_call.name == "delete_file"
Choose agent modelsallow
model.provider == "openai"
Restrict websitesdeny
http.host == "untrusted.example"

Detect threats.

Flag access to password files and secrets.

How to write a detection rule
title: Password file accessedlevel: highdetection:  selection:    file.read.name: passwords.txt  condition: selection
Password file accessedHigh

file.read.name = passwords.txt