Yafl

dev.yaflPublished by yafl.devv0.1.6Updated Oct 24, 2026

Agent-first E2EE file transfer over MCP: move files between machines in one tool call, gone in 24h.

VerifiedSTDIODesktop onlyFiles & Storage Security & Monitoring

Server details

Identifier: dev.yafl/mcp
Transport: STDIO
Runtime: Desktop only
Trust: Verified
Published: Sep 16, 2026

Security note

MCP servers receive tool arguments from a conversation and may perform external actions. Review what a server can do before you enable it, and give it only the access it needs.

The registry verified that this server's namespace belongs to yafl.dev. It runs from a package rather than a hosted endpoint, so there is no endpoint to match against that domain.

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Overview

AI-generated overview

YAFL is a local MCP server that lets an assistant upload, download, check, list, delete and email end-to-end encrypted file transfers that expire after 24 hours

What you can do: Upload files or directories, encrypted client-side, with optional password and one-time links, returning a share link and zipping directories first. Download and decrypt a transfer from a link to a local directory. Check a link's liveness and remaining time-to-live without downloading bytes. List your own transfers (metadata only) and revoke one before expiry. Email a share link to a recipient from within the session. Authorize the agent through a device-flow login that gives it its own revocable key.
When to use it: Useful when an assistant needs to hand files between machines or environments, such as laptop to VPS or agent to agent, without a person manually moving files or copying links. Also suited to headless boxes where a short-lived, encrypted share link is preferable to a permanent one.
Requirements: Runs locally via npx, requiring Node.js 18 or newer; no global install needed. An API key can be supplied through the YAFL_API_KEY environment variable, or omitted and replaced by a device-flow login approved in a browser. Network access to the YAFL service is required. Desktop MCP clients only.

Before you install

Uploads send file bytes to third-party storage, though encrypted on your machine; the service sees only ciphertext. The API key is not the decryption key, but a stolen key exposes metadata for that key's transfers, so use one revocable key per agent and machine. Links expire after 24 hours and the free tier caps files at 100 MB. The email_link tool sends a share link to a recipient outside the session.

Installation

In SourceWeft

Open Yafl in the dashboard and add it to a workspace.
Enable the server for the chats that should use its tools.

Desktop only via STDIO. STDIO servers start a local process, so they need the SourceWeft desktop host.

Other MCP clients

Follow the launch instructions in the repository.

README

YAFL — Yet Another File Layer (MCP server + CLI)

Your AI agent moves files between machines with one MCP call — encrypted client-side, links gone in 24 hours.

This repository is the open-source MCP server and CLI client for YAFL. Your agents (Claude Desktop, Claude Code, Cursor, any MCP client — including agents on remote VPSes) hand files across environments — laptop ↔ VPS, agent ↔ agent — with a single tool call, instead of a human dragging files into WeTransfer and copying links around. Files are encrypted on your machine before they leave it; the service only ever sees ciphertext.

The client is open source so you can audit exactly what touches your files. The YAFL service lives at yafl.dev.

Install

Add YAFL to your MCP client config:

json

{  "mcpServers": {    "yafl": {      "command": "npx",      "args": ["-y", "@yafldev/mcp"],      "env": { "YAFL_API_KEY": "<your key — or leave unset and run yafl login>" }    }  }}

{  "mcpServers": {    "yafl": {      "command": "npx",      "args": ["-y", "@yafldev/mcp"],      "env": { "YAFL_API_KEY": "<your key — or leave unset and run yafl login>" }    }  }}

Works in Claude Desktop, Claude Code, Cursor, and any MCP client. Claude Desktop users can install the one-click .mcpb bundle. Prefer the CLI:

No API key is required to start. On the first tool call the server returns a guided error pointing to yafl login — an RFC 8628 device flow: the agent shows a short code, you approve it in a browser, and the agent holds its own revocable key. Built for headless boxes. Runs via npx (Node.js 18+); no global install needed.

Tools

Tool	Call	What it does
`upload_file`	`{ path, password?, oneTime? }`	Encrypts client-side, uploads ciphertext, returns the share link. Zips a directory first. Optional password layer; optional one-time link that burns after the first download.
`download_file`	`{ url, destDir?, password? }`	Fetches, decrypts, writes the file to local disk.
`get_status`	`{ url }`	Checks liveness and remaining TTL — no bytes downloaded.
`list_files`	`{ limit? }`	The caller's own transfers, metadata only.
`delete_file`	`{ id \| url }`	Revoke one of your transfers before expiry.
`email_link`	`{ link, recipient }`	Email a share link straight to a recipient — the agent-to-human handoff without leaving the session.
`login`	device flow	Authorize this agent (RFC 8628); it holds its own revocable key.

Errors are stable and machine-readable — your agent gets expired or not_found, not a mystery 404.

How encryption works

The file is encrypted with a fresh AES-256-GCM key before upload. The key travels only in the share URL's #fragment — browsers never send fragments to servers, so it is never transmitted to, logged by, or stored on any server. An optional link password adds a second derived layer the server never sees either, and a one-time link self-destructs after the first successful download. File bytes go directly to storage via pre-signed URLs; the app server never handles them, and storage only ever receives ciphertext. Access stops at 24 hours. Free tier: 100 MB per file.

What happens if an agent's key leaks

The API key is not the decryption key. If a machine is compromised and its YAFL key is stolen, the attacker can at most see ciphertext metadata for that key's own transfers — file contents stay unreadable, because decryption keys exist only in the links you exchanged. Revoke the key and move on. This is why the recommended setup is one key per agent, per machine — keys are named and individually revocable.

License

MIT — see LICENSE.

Source: README.md at commit fdd803f

Tools

SourceWeft has not started this package in its sandbox yet, so its tools are not known.

Version history

v0.1.6LatestSep 16, 2026

Score

50% of the applicable checks met

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Reached in the last 30 days25 pts
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Auth declared10 pts
Declare the credential headers in the registry entry, or keep the endpoint answering the probe so its auth can be classified.
Tools listed15 pts
Answer tools/list without a credential, or ship a package that starts in a sandbox without one.
DescriptionRequired15 pts
Logo10 pts
Documentation15 pts
License10 pts