SFTP

SFTP (SSH File Transfer Protocol) via ssh2-sftp-client. Node-only. Connect-per-operation with an injectable client for batch work; url() needs an HTTP front.

Installation

ssh2-sftp-client is an optional peer dependency of files-sdk - install alongside the SDK so the adapter's imports resolve at runtime.

npm install files-sdk ssh2-sftp-client

SFTP via the ssh2-sftp-client library (built on ssh2). Virtual keys map to paths under a configurable root on the remote server, with a .. traversal guard. Node-only — SFTP uses raw sockets, so this adapter does not run on edge/browser/Workers runtimes.

By default the adapter opens a fresh connection per operation and closes it afterwards. For batch work, connect once and pass the client so every call reuses the same connection — you own its lifecycle.

import { Files } from "files-sdk";
import { sftp } from "files-sdk/sftp";

const files = new Files({
  adapter: sftp({
    host: "files.example.com",
    username: process.env.SFTP_USERNAME!,
    // Password or private-key auth (privateKey takes precedence):
    privateKey: process.env.SFTP_PRIVATE_KEY!,
    // passphrase: process.env.SFTP_PASSPHRASE,
    root: "/uploads", // virtual keys resolve under here; defaults to "."
  }),
});

await files.upload("reports/q1.csv", csv, { contentType: "text/csv" });
const file = await files.download("reports/q1.csv");

Auth falls back to SFTP_HOST, SFTP_USERNAME, SFTP_PASSWORD, SFTP_PRIVATE_KEY, SFTP_PASSPHRASE, and SFTP_PORT (default 22) when the matching option is omitted. Pass connectOptions to forward anything else to ssh2 (e.g. hostVerifier, algorithms, agent).

Reusing a connection

import SftpClient from "ssh2-sftp-client";

const client = new SftpClient();
await client.connect({ host: "files.example.com", username, privateKey });

const files = new Files({ adapter: sftp({ client }) });
// ...many operations over the one connection...
await client.end();

Method	Status	Notes
`upload`	⚠️	User `metadata` and `cacheControl` throw - SFTP files have no arbitrary-metadata or cache-header field. `contentType` is accepted for the return value but not stored (it's inferred from the key's extension on read). Stream bodies upload directly. Node-only (raw sockets).
`download`	✅
`delete`	✅
`list`	⚠️	Walks the directory tree recursively on every call - SFTP has no native prefix scan or pagination - and skips symlinks. `prefix`/`limit`/`cursor` are applied client-side over the full walk, so they're accurate but a large tree means a full traversal per call. Content type is inferred from each key's extension; `size`/`lastModified` come from the listing.
`head`	⚠️	SFTP stores no content type, etag, or user metadata - `head()` infers the type from the key's extension (or `application/octet-stream`) and returns no etag. `size` and `lastModified` come from `stat`.
`exists`	✅
`copy`	⚠️	Read-then-write - base SFTP has no portable server-side copy, so the source is downloaded and re-uploaded over one connection. The whole object is buffered in memory; not atomic.
`url`	❌	Throws unless `publicBaseUrl` is set (an HTTP server fronting the same tree), in which case it returns `<publicBaseUrl>/<key>`. SFTP serves no HTTP and has no signing primitive. `responseContentDisposition` also requires `publicBaseUrl`.
`signedUploadUrl`	❌	Throws - SFTP has no presigned-upload concept. Use `upload()`, or inject a pre-connected `client` for batch transfers.

Installation

Usage

Reusing a connection

Options

Limitations

Compatibility

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