Show HN: Tinysandbox – An ultra-minimal sandbox with QuickJS WASM isolates

Description and use

**Brief summary (2‑3 sentences)**
Tinysandbox is an ultra‑minimal sandbox library that runs QuickJS‑compiled WebAssembly isolates, letting you execute untrusted JavaScript safely in the browser. By providing a tiny, zero‑dependency API, it removes the need to build custom sandboxing logic for user‑facing interfaces, accelerating UI prototyping and component reuse.

**Value**

• **Speed to market** – Developers can embed a ready‑made, secure JS execution environment without writing low‑level sandbox code, so UI features that need user‑provided scripts (e.g., plugins, custom formulas, live previews) can be shipped faster.
• **Low footprint** – The library is only a few kilobytes, keeping bundle size small and preserving front‑end performance.
• **Consistency** – Using the same QuickJS‑WASM isolate across the app ensures uniform security guarantees and simplifies testing.

**Practical adoption path**

| Step | Action | Reason |
|------|--------|--------|
| 1️⃣ | **Review repository** – clone the repo, read the README, check the license (MIT/Apache‑style) and examine recent commit history. | Confirms legal compliance and maintenance activity. |
| 2️⃣ | **Run the demo** – execute npm run demo (or the provided HTML page) to see the sandbox in action and verify it meets your functional needs. | Quick sanity check before integration. |
| 3️⃣ | **Add as a dependency** – npm i tinysandbox (or use a CDN bundle) and import the API (import { createIsolate } from 'tinysandbox'). | Minimal integration effort; no extra build steps. |
| 4️⃣ | **Wrap your UI component** – create a thin wrapper that instantiates an isolate, feeds user code, and returns results via promises. | Isolates side‑effects and memory leaks. |
| 5️⃣ | **Add security hardening** – configure the QuickJS memory limits, timeout callbacks, and restrict exposed globals according to your threat model. | Aligns sandbox with production security policies. |
| 6️⃣ | **Automated tests** – add unit tests that simulate malicious payloads (e.g., infinite loops, global hijacking) to verify the sandbox behaves as expected. | Guarantees reliability before release. |
| 7️⃣ | **Monitor & update** – set up a Dependabot or Renovate job to watch for new releases and security advisories. | Keeps the dependency up‑to‑date. |

**Production readiness**

• **Maturity**: The project is updated as of 2026‑07‑05 and has a modest score (41/100). It is suitable for prototypes, internal tools, or low‑risk customer‑facing features, but it lacks extensive community adoption metrics.
• **Risks**: Sparse documentation, limited issue tracking, and an unclear release cadence mean you should perform a manual security audit and verify that the QuickJS‑WASM binary is built from a trusted source.
• **Recommendation**: Treat Tinysandbox as a **medium‑readiness** component—use it in non‑critical paths after thorough testing, and consider a fallback or alternative sandbox (e.g., iframe sandbox or SES) for high‑stakes production workloads.

Use in a workflow

Show HN: Tinysandbox – An ultra-minimal sandbox with QuickJS WASM isolates helps ship user-facing interfaces with less custom UI work.

• build product UI faster
• reuse interface components
• improve frontend delivery

Limitations and review notes

Medium: useful for prototypes or internal workflows, with dependency and maintenance checks before production.