# Kyushu

A Self-Hostable Wasm Sandbox for JavaScript Workers — run a Cloudflare Workers-style handler on a VPS or anywhere, without Node.js, Bun, or even Docker.

Source: https://wheredoirunthis.com/products/kyushu · JSON: https://wheredoirunthis.com/api/products/kyushu · Read on 2026-10-14

## At a glance

- Type: Serverless
- Kind: Open source tool
- Isolation: WebAssembly
- Free tier: Not documented
- Starting price: Not disclosed
- GPU: No
- Regions: Not disclosed
- Coverage: 3 of 61 assessed capabilities supported
- Agent readiness: read 5 of 10 signals, drive 1 of 8 signals

## Links

- Homepage: https://kyushu.dev/
- Docs: https://kyushu.dev/getting-started
- Repository: https://github.com/peterpeterparker/kyushu

## Website design

Desktop public website · assessed 2026-10-14

Complete assessment.

The desktop landing and getting-started documentation share a restrained white, text-led presentation with fine dividers, dark command panels and a small illustrated logo. Documentation adds persistent side navigation and colored instructional callouts; hosted pricing is not applicable to this MIT-licensed self-hosted CLI.

- Styles: Editorial minimalism
- Landing page: captured
- Pricing: not applicable
- Docs: captured

## Runtime

- **GPU & accelerators**: No — "No GPU — a CPU wasm worker runtime." [source](https://kyushu.dev/)
- **BYOC (Bring your own cloud)**: na [source](https://kyushu.dev/)
- **Secrets management**: Explicit worker.env key/value injection into the worker; no dedicated secret vault or rotation documented. [source](https://kyushu.dev/reference/configuration)
- **Storage options**: Explicit host/guest filesystem mounts, read-only by default with writable opt-in; static assets can be embedded in the worker or served from filesystem. No managed database/object store. [source](https://kyushu.dev/reference/configuration)
- **Supported workloads**: Self-hosted JS/TS HTTP fetch handlers, Static websites/assets embedded into a Wasm worker, Experimental sandboxing of user-defined or third-party logic; production untrusted input explicitly cautioned against [source](https://github.com/peterpeterparker/kyushu)
- **Persistence**: JavaScript module state is reset between requests. Explicit host filesystem mounts may be writable and retain operator-owned files; no managed persistent volume service. [source](https://kyushu.dev/reference/configuration)
- **Data jurisdiction**: na [source](https://kyushu.dev/)
- **Resource limits & quotas**: No documented operator-facing memory/fuel/concurrency quotas in the current run configuration. Experimental, unaudited runtime. [source](https://kyushu.dev/reference/configuration) (confidence: medium)
- **SDK languages**: JavaScript, TypeScript [source](https://kyushu.dev/getting-started)
- **Network & egress controls**: Outbound DNS name lookup, TCP and UDP are individually disabled by default and enabled with worker.network.ip_name_lookup/tcp/udp. No per-destination allowlist documented. Outbound fetch uses wasi:http separately; do not interpret these raw socket flags as a verified HTTP deny policy. [source](https://kyushu.dev/reference/configuration) (confidence: high)
- **Snapshots & forks**: Wizer freezes pre-initialized JavaScript memory into the build artifact. No user-facing checkpoint/fork of a live serving instance documented. [source](https://github.com/peterpeterparker/kyushu)
- **Deployment methods**: cli [source](https://kyushu.dev/getting-started)
- **Isolation**: WebAssembly — "'The worker is a wasm32-wasip2 component that embeds a QuickJS JavaScript runtime ... The runner (kyu run) is a Rust binary powered by Wasmtime ... Your JavaScript runs inside the sandbox - isolated from the host filesystem and environment, except for what you explicitly allow via config.' WebAssembly (Wasmtime host) sandbox." [source](https://github.com/peterpeterparker/kyushu) (confidence: high)

## Capabilities

### AI & agents

| Capability | Status | Evidence |
| --- | --- | --- |
| Agent skills | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| AI app builder | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Autonomous QA agent | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Built-in coding agent | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| BYOK for LLMs | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Credential-injection proxy | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| LLM gateway | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| MCP client | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| MCP-server hosting | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| MCP server | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Model inference API (first-party) | Not applicable | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Preinstalled coding agent | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |

### Networking & delivery

| Capability | Status | Evidence |
| --- | --- | --- |
| Automatic HTTPS | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Custom domains | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Direct public IPv6 | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Edge KV store | Not applicable | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Egress controls | Partially supported | "Allow outbound TCP connections" [source](https://kyushu.dev/reference/configuration) |
| Email send / receive | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Public preview URLs | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Private networking | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Built-in reverse proxy | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |

### Organisation & security

| Capability | Status | Evidence |
| --- | --- | --- |
| Built-in auth | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| BYOC | Not applicable | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Deploy into customers' VPCs | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Secrets management | Partially supported | "Environment variables to expose to the worker" [source](https://kyushu.dev/reference/configuration) |
| Self-host / OSS core | Supported | "Permission is hereby granted, free of charge, to any person obtaining a copy" [source](https://github.com/peterpeterparker/kyushu/blob/main/LICENSE) |
| Sharing | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| SSO / SAML | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Teams | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Workload identity | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |

### Developer access

| Capability | Status | Evidence |
| --- | --- | --- |
| CLI | Supported | "kyu dev [config]" [source](https://kyushu.dev/reference/cli) |
| E2B-compatible API | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Filesystem API | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Git deploy | Partially supported | "This guide covers automating the deployment of a Kyushu worker to a VPS using GitHub Actions." [source](https://kyushu.dev/guides/github-actions) |
| HTTP data API | Not applicable | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| OpenAPI spec | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Private container registry | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Public API | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| SDK | Partially supported | "For autocompletion, install the `kyushu-types` library." [source](https://kyushu.dev/getting-started) |
| SSH access | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |

### Compute & storage

| Capability | Status | Evidence |
| --- | --- | --- |
| Cloud-init / ignition config | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Desktop / computer-use sandbox | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| GPU compute | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Live-state (memory) snapshots | Supported | "The resulting `.wasm` file contains your code frozen in memory, ready to handle requests with no startup overhead." [source](https://kyushu.dev/how-it-works) |
| Multi-region | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Object storage | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Persistent disk | Partially supported | "Read and write files by mounting a host directory into the sandbox." [source](https://kyushu.dev/examples/file-system) |
| Sandbox templates / custom images | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Scale to zero | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Selectable isolation runtime | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Snapshots / forking | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |

### Data

| Capability | Status | Evidence |
| --- | --- | --- |
| Database branching | Not applicable | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Ephemeral instant DB (no-signup) | Not applicable | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| First-party database | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Vector search | Not applicable | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |

### Platform & operations

| Capability | Status | Evidence |
| --- | --- | --- |
| Managed CI/CD runners | Not applicable | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Built-in observability | Partially supported | "Only log starting from the `fetch` handler, not at module scope (which is ignored)." [source](https://github.com/peterpeterparker/kyushu) |
| Preview environments | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Scheduled tasks | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Project template marketplace | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |
| Durable workflows | Not supported | "Write a simple `fetch` handler, build it into a self-contained WebAssembly binary, and run it anywhere with a single CLI binary - `kyu`." [source](https://github.com/peterpeterparker/kyushu) |

## Agent readiness

### Read: 5 of 10 signals present

5/10 signals (4 full, 2 partial)

- Llms txt: fail — "/llms.txt + /.well-known/llms.txt both 404."
- Llms full txt: fail — "/llms-full.txt 404."
- Robots AI policy: partial — "/robots.txt 404 = default-allow (nothing disallowed) = half per rubric v3."
- JSON LD: fail — "0 <script type=application/ld+json> on the homepage."
- Sitemap: pass — "https://kyushu.dev/sitemap-index.xml links sitemap-0.xml with 19 official page URLs, both retained."
- Meta quality: pass — "Complete title + description + OG (title/description/image/type) + Twitter summary_large_image; descriptive."
- Markdown negotiation: fail — "Accept: text/markdown returned HTML; .md probe returned 404. Retained homepage-markdown.txt and probe manifest."
- Content efficiency: partial — "Retained homepage.html: 1084 readable UTF-8 text bytes / 24308 HTML bytes = 4.46% after excluding script/style text; within 1–5% half-credit band."
- Docs discoverable: pass — "Homepage hero links 'Get started' / 'Read docs' -> /getting-started, first-class without JS."
- Pricing machine readable: na — "oss-tool — no pricing (/pricing 404)."
- Anti bot: pass — "Fresh anonymous browser and retained homepage/docs/raw well-known fetches did not show a public bot challenge."

### Drive: 1 of 8 signals present

1/8 signals (1 full, 0 partial)

- Public API: fail — "No programmatic HTTP control API — the interface is the `kyu` CLI."
- Openapi spec: fail — "No OpenAPI spec."
- MCP server: fail — "No MCP server."
- SDK packages: fail — "Official kyushu-types is an authoring types package, not a functional API client SDK; no client SDK documented."
- Auth docs: na — "Self-hosted CLI — no hosted API to authenticate."
- Agent self serve creds: na — "No hosted signup/credential issuance (self-host)."
- Webhooks: fail — "No webhooks."
- CLI tool: pass — "https://kyushu.dev/reference/cli documents kyu build, run, dev and --version."
- Error model: fail — "No documented JSON error model (worker responses are user-defined)."
- Rate limit docs: na — "Self-hosted — no hosted API rate limiting."
- Agent config: fail — "No agents.md / /.well-known/agent / skills listing."

## Open source

- Repository: https://github.com/peterpeterparker/kyushu
- License: MIT
- Stars: 193
- Forks: 4
- Self-host methods: binary, source-build

## Company & presence

- Founded: 2026-05-29
- GitHub: https://github.com/peterpeterparker/kyushu
- Website / docs: https://kyushu.dev/

## Nearby in the atlas

- [Beam](/products/beam.md)
- [Chutes](/products/chutes.md)
- [Deno Deploy](/products/deno.md)
- [Koyeb](/products/koyeb.md)
- [Modal](/products/modal.md)
- [NVCF (NVIDIA Cloud Functions)](/products/nvcf.md)

## Method

Facts come from the product's own public pages. Each claim carries its evidence: a quote and the page it came from. We count capabilities rather than grade products, and "Not assessed" means we have not checked, never that the product lacks it.