---
title: FAQ
description: Common questions about supported providers, bundling and peer dependencies, switching backends, browser uploads, error handling, and the CLI.
---

## Which providers are supported?

49 adapters, behind one API: AWS S3 and the whole S3-compatible long tail (R2, MinIO, RustFS, Backblaze, Wasabi, DigitalOcean Spaces, Scaleway, OVH, Hetzner, Tigris, Storj, Filebase, Akamai, IDrive, Vultr, IBM COS, Oracle, Exoscale, Alibaba, Tencent, Yandex, Archil, Neon, Railway Buckets), Vercel Blob, Netlify Blobs, Google Cloud Storage, Azure, Supabase, the consumer providers (Dropbox, Box, Google Drive, OneDrive, SharePoint), upload and media services (UploadThing, Cloudinary, Bunny Storage), the BaaS stack (Appwrite, PocketBase, Firebase Storage, Convex), FTP, SFTP, and WebDAV servers, Bun's native S3 client, and local `fs` and in-memory adapters for tests. The [provider catalog](/docs/providers) lists every one, and each has its own page under [Adapters](/docs/adapters/s3).

## Do I have to install every provider's SDK?

No. Adapters are subpath exports (`files-sdk/s3`, `files-sdk/r2`, ...) and each provider SDK is an optional peer dependency, loaded only when you import that adapter's subpath. Install only the one(s) you wire up - the SDK you don't import is never bundled. See [Installation](/docs/installation).

## Why am I getting "Cannot find module '@aws-sdk/client-s3'"?

Provider SDKs are peer dependencies - install only the ones for the adapters you use. The per-adapter docs list the exact packages.

## How do I switch providers?

Swap the adapter you pass to `new Files({ adapter })`. Every call site below the constructor stays identical - the code that uploads to S3 is the code that uploads to Vercel Blob. See [Usage](/docs/usage).

## What happens when a provider doesn't support a feature?

Every method normalizes to the same shape, but providers differ in what they offer natively. Where a provider lacks a primitive, the method throws a `FilesError` rather than silently misbehaving (for example, `signedUploadUrl` on Bunny Storage). Each [adapter's docs page](/docs/adapters/vercel-blob) has a Compatibility section listing its per-method support, and `files.raw` is the [typed escape hatch](/docs/escape-hatch) for anything outside the unified surface.

## Can I use it in the browser?

The core `Files` class and the `StoredFile` type are isomorphic, but most adapters wrap server-only SDKs. For browser uploads, mint a contract with [`signedUploadUrl()`](/docs/api/signed-upload-url) on the server and have the client `fetch` directly to the provider - the [`signedUploadUrl` reference](/docs/api/signed-upload-url) walks through the full pattern, and the [UI](/docs/ui) gateway and `useFiles` bindings package it up for React, Vue, and Svelte.

## How are errors handled?

Every method throws a single `FilesError` with a normalized `code` - `NotFound`, `Unauthorized`, `Conflict`, `ReadOnly`, `Invalid`, `Unsupported`, or `Provider` - and the original provider error attached as `cause`. See [Errors](/docs/api/errors).

## Does `delete` throw on a missing key?

Depends on the provider. S3, R2, Vercel Blob, FTP, Bunny Storage, and the local `fs` adapter treat a missing key as a successful no-op (other failures, such as a permission error, still throw); strict providers throw a `FilesError` with `code: "NotFound"`. If you need consistent behavior, gate on `await files.exists(key)` first. See [delete](/docs/api/delete).

## Why is `contentType` `application/octet-stream`?

When `upload` can't infer the type from the input (an `ArrayBuffer`, typed array, `ReadableStream`, or a `Blob` with no `type`), it defaults to `application/octet-stream`; strings default to `text/plain; charset=utf-8`. The key's extension isn't used. Pass `contentType` explicitly to override it, or add the [`contentType()`](/docs/plugins/content-type) plugin to detect it from the file's bytes.

## Why does the body come back empty from `head` / `list`?

`head`, `list`, and `search` return [`FileInfo`](/docs/api/stored-file): plain metadata with no body, so it serializes as-is. Only `download` returns a body, as a `StoredFile`; call `.arrayBuffer()` / `.text()` / `.blob()` / `.stream()` on that.

## Is there a CLI?

Yes - a `files` binary with JSON-by-default output, stdin/stdout streaming, and a built-in MCP server, with the same semantics as the SDK. See the [CLI](/docs/cli) docs.