What It Does
CodeSandbox SDK is a programmatic API for creating and running VM sandboxes, originally built by CodeSandbox and now integrated with Together AI following their acquisition in December 2024. Each sandbox runs inside a microVM with snapshot/hibernation and forking capabilities — you can fork a running sandbox to create instant copies that share the parent’s state. VMs spin up in under 3 seconds, and memory snapshots restore in under 2 seconds.
The SDK provides sandboxes for AI agent code execution, educational platforms, and web development environments. Together AI has expanded infrastructure capacity since the acquisition, lowering pricing and raising rate limits.
Key Features
- MicroVM isolation: Each sandbox runs in its own microVM, providing hardware-level isolation
- Snapshot/hibernation: Save sandbox state and resume after inactivity — useful for long-running agent sessions
- VM forking: Fork a running sandbox to create instant copies sharing parent state — enables parallel experimentation
- Sub-3-second creation: Fresh VMs in under 3 seconds; memory snapshot restores in under 2 seconds
- Together AI integration: Integrated as Together Code Sandbox within the Together AI inference platform
- Free tier available: Usage-based scaling beyond free tier
Use Cases
- Web development agent sandboxes: Running AI-generated frontend/backend code in isolated environments
- Educational platforms: Providing sandboxed coding environments for students with snapshot/restore
- Together AI customers: Teams already using Together AI for inference who want integrated sandbox capabilities
Adoption Level Analysis
Small teams (<20 engineers): Reasonable fit. Free tier for experimentation. The forking mechanism is useful for agent development. However, the acquisition by Together AI introduces uncertainty about long-term product direction.
Medium orgs (20-200 engineers): Moderate fit. The snapshot/hibernation and forking features are genuinely useful. However, the product’s direction is now controlled by Together AI (an inference platform), and sandbox features may become secondary to Together’s core business.
Enterprise (200+ engineers): Limited fit. SOC2 is documented (from pre-acquisition CodeSandbox). However, the Together AI acquisition creates strategic uncertainty. Enterprise teams should prefer E2B or Northflank for long-term stability.
Alternatives
| Alternative | Key Difference | Prefer when… |
|---|---|---|
| E2B | Firecracker microVMs, market leader, ephemeral focus | You want the most established sandbox platform with widest ecosystem support |
| Sprites (Fly.io) | Persistent Firecracker with checkpoint/restore and auto-sleep | You need persistent state with auto-sleep billing |
| Runloop | Custom hypervisor with SWE-bench integration | You need agent benchmarking capabilities |
Evidence & Sources
- CodeSandbox SDK official page
- CodeSandbox blog: Joining Together AI and Introducing SDK
- Together AI: CodeSandbox acquisition announcement
- PR Newswire: Together AI acquires CodeSandbox
- AI Agent Sandboxes Compared — Ry Walker
Notes & Caveats
- Acquired by Together AI (Dec 2024): Product direction may shift toward Together AI’s inference platform needs. Standalone sandbox features may receive less investment.
- Strategic uncertainty: Together AI is an inference company, not a sandbox company. Long-term commitment to the SDK as a standalone product is unclear.
- Slower creation than E2B/Daytona: Sub-3-second creation is 20x slower than E2B (150ms) or Daytona (90ms). Not suitable for high-throughput batch evaluation.
- Pre-acquisition SOC2 status: SOC2 certification was achieved pre-acquisition. Verify current compliance status if this matters for your use case.