Filelayer MCP server

Filelayer

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Alpha — developer preview, not production software. Nobody is running it

in production, including us. Should you depend on this?

has the real numbers, including the ones that are zero, and exactly what would

change them. Limitations is the complete list of what it

does not do.

We are looking for three to five design partners. If you are building

something with private user files, we will help you integrate this and stay on

hand while you do, in exchange for telling us where it breaks. That is the only

thing on our roadmap to 1.0 we cannot build ourselves.

Open an issue or say hello.

The file layer for SaaS applications. Public files and private files, with one authorization model behind both.

You tell Filelayer who the caller is. Filelayer decides what they may do with a file, serves the bytes with the right headers, and writes the audit event. For file access that goes through Filelayer, that decision is made in one place, packages/core/src/authz.ts, so you write no ownership checks in route handlers, no presigned-URL expiry logic, and no per-route access rules of your own.

Filelayer is authorization middleware, not row-level security. It runs in your application process, in front of Postgres and your bucket. Code that queries these tables directly does not go through it. The schema does enforce a set of invariants against every writer: cross-tenant grants, cross-project identities, and delegation that amplifies authority or subject breadth are refused by constraints and triggers, so a migration or a psql session cannot write them. But there is no RLS policy in schema.sql, and a direct SELECT is not filtered by anything. If you need enforcement that survives arbitrary database clients, use database-level enforcement; Filelayer is the layer above it, and the two compose.

<!-- doccheck-setup import { Filelayer } from '@filelayer/core'; const fl = await Filelayer.quickstart({ baseUrl: 'http://localhost:3000' }); const bytes = new TextEncoder().encode('hello'); -->

// Public avatar
const { url } = await fl.files.put(bytes, { public: true });

// Private, user-owned
const { id } = await fl.files.put(bytes, { owner: 'user_123' });
const file  = await fl.files.get(id, { as: 'user_123' });

// Multi-tenant, role-controlled
await fl.files.put(bytes, { org: 'acme', owner: 'user_123' });

// Shared with an expiry, a password and a download cap, and revocable
const share = await fl.shares.create(id, {
  as: 'user_123', expiresIn: 3600, maxDownloads: 3, password: 'hunter2',
});
await fl.shares.revoke(share.grantId, { as: 'user_123' });   // this link, now

// Shared with a named user, and taken back. `unshare` is the one you want for
// a person: `create()` is not idempotent, so revoking a single grant id you
// happen to be holding can leave an earlier one live.
await fl.shares.create(id, { as: 'user_123', withUser: 'user_456' });
await fl.shares.unshare(id, { as: 'user_123', user: 'user_456' });   // all of it

Shortened. The full README is on GitHub.