Key takeaways
- Forking mechanism enables A/B testing different agents on identical environments
- Acquired by Together AI (Dec 2024), now powers Together Code Interpreter
- Mature platform heritage from 7+ years building browser-based dev environments
FAQ
What is CodeSandbox SDK?
CodeSandbox SDK provides programmable microVM environments for AI agents with forking, snapshots, and hibernation capabilities.
Was CodeSandbox acquired?
Yes, Together AI acquired CodeSandbox in December 2024 to power their Together Code Interpreter feature.
Who competes with CodeSandbox SDK?
E2B, Daytona, Modal, Runloop, and Fly.io Sprites are direct competitors.
Executive Summary
CodeSandbox SDK provides programmable microVM environments for AI agents with unique forking capabilities for A/B testing. Originally a browser-based IDE company founded in 2017, CodeSandbox was acquired by Together AI in December 2024 to power their Together Code Interpreter feature.
| Attribute | Value |
|---|---|
| Company | CodeSandbox (acquired by Together AI) |
| Founded | 2017 |
| Funding | $15.2M (pre-acquisition) |
| Employees | ~25 (remote-first) |
| Headquarters | Amsterdam, Netherlands |
Product Overview
CodeSandbox was founded in 2017 by Ives van Hoorne and Bas Buursma as a browser-based development environment. Over seven years, they built expertise in isolated code execution environments, eventually launching the SDK to let developers programmatically create and manage sandboxes.
In December 2024, Together AI acquired CodeSandbox to integrate their sandbox technology into the Together Inference Platform as the Together Code Interpreter. The SDK continues to operate, now with the backing of a major AI infrastructure company.
Key Capabilities
| Capability | Description |
|---|---|
| Forking | Clone sandboxes instantly for A/B testing agents |
| Snapshots | Save and restore sandbox state |
| Hibernation | Auto-hibernate idle sandboxes to reduce costs |
| Quick Resume | Restore hibernated sandboxes in ~2 seconds |
| Multi-Region | Data centers in US, APAC, and EMEA |
| Persistent Storage | Git-based source control for persistence |
Product Surfaces / Editions
| Surface | Description | Availability |
|---|---|---|
| JavaScript SDK | npm install @codesandbox/sdk | GA |
| REST API | HTTP endpoints for sandbox management | GA |
| Together Integration | Together Code Interpreter | GA |
| Browser IDE | Full CodeSandbox development environment | GA |
Technical Architecture
CodeSandbox uses microVMs for isolation, providing rapid startup times (~2 seconds) while maintaining security boundaries between sandboxes. The architecture supports persistent storage through git integration.
┌─────────────────────────────────────────┐
│ CodeSandbox SDK Platform │
├─────────────────────────────────────────┤
│ ┌──────────┐ ┌──────────┐ │
│ │ Sandbox │──│ Fork │ │
│ │ (μVM) │ │ (μVM) │ ... │
│ └────┬─────┘ └────┬─────┘ │
│ │ │ │
│ ┌────┴─────────────┴─────┐ │
│ │ Snapshot Store │ │
│ │ (Git-based) │ │
│ └────────────────────────┘ │
│ │
│ ┌────────────────────────────────┐ │
│ │ Multi-Region microVMs │ │
│ │ (US, APAC, EMEA) │ │
│ └────────────────────────────────┘ │
└─────────────────────────────────────────┘
Key Technical Details
| Aspect | Detail |
|---|---|
| Isolation | microVMs (hardware-level) |
| Cold Start | ~2 seconds |
| Persistence | Git-based with snapshots |
| Forking | Instant sandbox cloning |
| Hibernation | Auto-sleep with quick resume |
| Open Source | No (proprietary) |
Strengths
- Forking mechanism — Unique ability to instantly clone sandboxes for A/B testing different agents
- Mature platform — 7+ years of experience building isolated code execution environments
- Together AI backing — Acquisition by well-funded AI infrastructure company ensures longevity
- Multi-region — Data centers in US, APAC, and EMEA for low-latency access
- Hibernation — Auto-sleep reduces costs for intermittent workloads
- Continuous context — Resume development in the same sandbox after inactivity
- Web development heritage — Particularly strong for frontend/web agent use cases
Cautions
- Acquisition uncertainty — Integration with Together AI may shift product focus
- Less AI-focused — Originally built for human developers, not specifically AI agents
- Slower cold starts — ~2 seconds vs 90-150ms for dedicated AI sandbox platforms
- Not open source — Proprietary platform; no self-hosting option
- Limited GPU support — No GPU access; ML workloads need Modal
- Smaller AI ecosystem — Fewer AI-specific integrations than E2B or Daytona
Pricing & Licensing
| Tier | Price | Includes |
|---|---|---|
| Free | $0 | Limited sandboxes for development |
| Usage-Based | Pay-per-use | Full SDK access |
| Enterprise | Custom | SLAs, dedicated support |
Licensing model: Proprietary, usage-based pricing
Note: Pricing may evolve under Together AI ownership; Together Code Interpreter has separate pricing
Competitive Positioning
Direct Competitors
| Competitor | Differentiation |
|---|---|
| E2B | E2B is AI-native with Firecracker isolation; CodeSandbox has forking and web dev heritage |
| Daytona | Daytona has Computer Use and faster starts; CodeSandbox has mature tooling and forking |
| Modal | Modal has GPUs; CodeSandbox is sandbox-focused with web dev strength |
| Runloop | Runloop has SWE-bench; CodeSandbox has forking and Together AI integration |
When to Choose CodeSandbox SDK Over Alternatives
- Choose CodeSandbox SDK when: You need forking for A/B testing agents, or building web development agents
- Choose E2B when: You want AI-native infrastructure with larger ecosystem
- Choose Daytona when: You need Computer Use or fastest creation time
- Choose Runloop when: You're focused on coding agent benchmarking
Ideal Customer Profile
Best fit:
- Teams already using CodeSandbox for development
- Web development agent use cases (frontend, full-stack)
- Organizations wanting forking for A/B testing agent approaches
- Together AI customers wanting integrated code interpretation
- Educational platforms needing isolated student environments
Poor fit:
- Teams needing fastest cold starts (E2B, Daytona faster)
- Security-critical workloads wanting open-source transparency
- GPU-required ML workloads (Modal better fit)
- Teams wanting self-hosted deployment
Viability Assessment
| Factor | Assessment |
|---|---|
| Financial Health | Strong — Now backed by Together AI |
| Market Position | Challenger — Established but pivoting to AI focus |
| Innovation Pace | Moderate — Integration focus post-acquisition |
| Community/Ecosystem | Established — Large existing user base |
| Long-term Outlook | Positive — Together AI backing ensures resources |
The Together AI acquisition provides financial stability and clear strategic direction. The question is whether CodeSandbox's web development heritage translates effectively to AI agent use cases, where competitors like E2B and Daytona were built AI-native.
Bottom Line
CodeSandbox SDK offers mature sandbox infrastructure with a unique forking capability that enables A/B testing different agent approaches on identical environments. The acquisition by Together AI ensures longevity and integration with a major AI inference platform.
The trade-off is that CodeSandbox wasn't built AI-native — it evolved from a browser-based IDE into agent infrastructure. Platforms like E2B and Daytona were purpose-built for AI agents and may have advantages in performance and AI-specific features.
Recommended for: Teams needing forking for A/B testing, building web development agents, or already using Together AI infrastructure.
Not recommended for: Teams needing fastest cold starts, open-source transparency, or GPU access.
Outlook: CodeSandbox will likely become more deeply integrated with Together AI's inference platform. Expect the SDK to continue operating while Together Code Interpreter becomes the primary product focus.
Research by Ry Walker Research • methodology