Backend Adapters

Getting started with Fastify

Added in v5.6

Package Setup

Install the package

npm install uploadthing

Add env variables


If you don't already have a uploadthing secret key, sign up (opens in a new tab) and create one from the dashboard! (opens in a new tab)

UPLOADTHING_SECRET=... # A secret key for your app (starts with sk_live_)
UPLOADTHING_APP_ID=... # Your app id

Set Up A FileRouter

Creating your first FileRoute

All files uploaded to uploadthing are associated with a FileRoute. The following is a very minimalistic example, with a single FileRoute "imageUploader". Think of a FileRoute similar to an endpoint, it has:

  • Permitted types ["image", "video", etc]
  • Max file size
  • (Optional) middleware to authenticate and tag requests
  • onUploadComplete callback for when uploads are completed

To get full insight into what you can do with the FileRoutes, please refer to the File Router API.

import { createUploadthing, type FileRouter } from "uploadthing/fastify";
const f = createUploadthing();
export const uploadRouter = {
  imageUploader: f({
    image: {
      maxFileSize: "4MB",
      maxFileCount: 4,
  }).onUploadComplete((data) => {
    console.log("upload completed", data);
} satisfies FileRouter;
export type OurFileRouter = typeof uploadRouter;

Register the UploadThing plugin

import Fastify from "fastify";
import { createRouteHandler } from "uploadthing/fastify";
import { uploadRouter } from "./router";
const fastify = Fastify({ logger: true });
  /** ... */
  .register(createRouteHandler, {
    router: uploadRouter,
    config: { ... },

See configuration options in server API reference

Use the FileRouter in your app

Client side usage differs ever so slightly from the fullstack framework setups when using a separate backend server. You'll need to set the URL of your server when you generate the components and helpers.

import { generateUploadButton } from "@uploadthing/react";
export const UploadButton = generateUploadButton({
  url: "",
// ...

Please note that you might need to setup some CORS rules on your server to allow the client to make requests to the server.

For the remaining usage, please refer to client side examples of the fullstack framework guides: