Fences, Not Sandboxes: A New Approach to System Design

tosh· August 24, 2026 View original

Key takeaways

  • The "fences" philosophy prioritizes strong, explicit boundaries in system design.
  • It contrasts with "sandboxes," which offer flexibility but may lack stringent control.
  • Adopting "fences" can lead to more secure and predictable systems.
  • This approach is particularly relevant for high-security or critical infrastructure applications.

Who benefits

CybersecuritySoftware DevelopmentCloud ComputingFinancial ServicesGovernment

Summary

This post advocates for a system design philosophy that prioritizes "fences" – robust, clearly defined boundaries and protections – over "sandboxes," which offer more flexibility but potentially less security or control. It suggests a shift towards more structured and secure environments.

The article presents an argument for adopting a "fences" approach in system architecture and design, contrasting it with the more common "sandbox" methodology. It posits that while sandboxes offer flexibility and isolation, they may not provide the stringent security and control needed for certain applications. The author suggests that establishing clear, strong boundaries and explicit rules ("fences") can lead to more secure, predictable, and manageable systems, particularly in environments where risk mitigation is paramount.

Why it matters

For engineering and product leaders, this perspective challenges conventional wisdom in system design, prompting a re-evaluation of security, control, and flexibility trade-offs in their architectural decisions.

How to implement this in your domain

  1. 1Review current system architectures to identify areas where "sandbox" approaches might be replaced by "fences" for enhanced security.
  2. 2Develop stricter access control policies and data segregation mechanisms within existing systems.
  3. 3Train engineering teams on the principles of "fences" design, emphasizing explicit boundaries and secure defaults.
  4. 4Evaluate new project designs with a focus on implementing robust, unbreachable perimeters rather than flexible, isolated zones.

Original post by tosh

"Fences, Not Sandboxes"

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Originally posted by tosh on X · view source

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