streamich/memfs

Health v2 · maintenance only

Adoption not part of the score

2089 stars · 150 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

memfs is a TypeScript library providing in-memory implementations of the Node.js `fs` module API and the browser File System Access API, plus adapters between the two. It lets code that expects a real filesystem run against a virtual one in tests, browsers, or sandboxed environments.

Use cases

• mock the node fs module in unit tests
• run node fs code in the browser
• use an in-memory filesystem for jest tests
• adapt between node fs and File System Access API
• test file-watching logic without touching disk
• snapshot and print virtual directory trees

When to choose

• you need to unit-test code that reads/writes files without hitting the real disk
• you want to run Node-style fs code in a browser or sandboxed environment
• you need fs/File System Access API interop adapters or OPFS file watching

When to avoid

• you need a persistent on-disk filesystem
• you need POSIX-perfect semantics like real permissions or hard links
• your project is not JavaScript/TypeScript

Facets

library · maturity active

file-system testing developer-tools developer-tools files testing web-development browser cross-platform in-memory-filesystem fs-mock opfs file-system-access-api typescript fs-adapters nodejs javascript

Member repositories

For agents

markdown · JSON · MCP: product_card(name="streamich/memfs")