How to Upload Files to AWS S3 From NextJS App | by Szymon Kolber | Apr, 2022

With out the wrestle with CORS coverage.

Requests making an attempt to succeed in the totally different origin

NextJS is a frontend framework, and because the frontend doesn’t have an entry to the totally different origins because of the CORS coverage, it’s tedious to implement it if you happen to’re doing it within the fallacious means. In fact which you can alter going out requests within the subsequent.config.js file with redirection from an API route, however then utilizing NextJS serverless API which is tremendous helpful, lose its advantages. On this “quick, to the purpose” article we’re gonna go over the steps wanted as a way to make it work.

Btw if you happen to want to work with prepared code, you could find such right here:

Should you don’t know what AWS S3 is, S3 stands for Easy Storage Service and it’s precisely that. It lets you retailer the entire totally different recordsdata on-line on Amazon servers, and retrieve them quick and safely. An extra bonus is the “pay as you scale” enterprise mannequin, which allow you to strive the service out, even use it in manufacturing without cost if you happen to’re wants aren’t that large. With that stated, let’s now deal with what we have now to do as a way to use it in our internet app.

1. Create an AWS account

You may register to the console there. The distinction between a root consumer and an IAM consumer is, {that a} root consumer’s credentials are the credentials by way of which you’ve registered, offering your card and billing particulars. IAM consumer accounts are those, which you create for particular person AWS companies. Summing it up, you wish to create a root consumer there.

Amazon register to the console web page

2. Navigate to the S3 / IAM service

AWS display screen after logging in

If it’s your first time utilizing AWS, don’t fear, it’s intuitive. Principally, you’ve got an entry to the entire companies from one account, and also you seek for them both from the just lately visited companies part or the search bar. Within the case of this tutorial, we’ll want simply two companies — S3 which is able to present us with storage capabilities, and IAM the place we’ll create entry insurance policies.

1. Making a bucket

The very first thing which we’ll gonna configure is S3. As you’ll be able to see within the under picture S3 works on “Buckets” philosophy. You create a bucket through which you’ll gonna retailer your recordsdata.

Bucket web page

Whereas making a bucket you’d most likely like to depart nearly every part as it’s, with an exception to the “block all public entry” possibility. Since we wish to permit a public add from our customers, we’ll stay it empty.

Leaving the “Block all public entry” possibility empty

2. Bucket properties configuration

Bucket Insurance policies — are answerable for managing entry. For the sake of simplicity, we’re gonna set it to the general public so we will entry the useful resource afterward with none pointless authentication. The configuration is fairly customary. Simply keep in mind to insert your bucket identify within the place of YOUR_BUCKET_NAME_HERE if you happen to’re copy-pasting it (in fact you’re, we’re all programmers).

"Model": "2012-10-17",
"Assertion": [

"Sid": "PublicListGet",
"Effect": "Allow",
"Principal": "*",
"Action": [
"Useful resource": [


CORS — Cors properties additionally will be set from inside the permissions tab. Be at liberty to copy-paste my configuration, which as you’ll be able to see is nothing loopy. We mainly permit the entire origins to entry our bucket.


"AllowedHeaders": [
"AllowedMethods": [
"AllowedOrigins": [
"ExposeHeaders": [


IAM aka API Key

Since we’re gonna join with Amazon we want some kind of authentication. We are able to do it from the IAM part. As you’ll be able to see I have already got one consumer group created

Consumer teams web page

Click on create group, and also you’ll be capable of select acceptable rights. Merely go along with AmazonS3FullAccess.

Setting group permissions

Afterward, you need to see a gaggle that you simply’ve simply created in your panel.

Created group

Then we wish to create a Consumer to which we’ll assign an entry group created a second in the past.

Creating an IAM consumer

Select programmatic entry since we wish to elevate AWS SDK utilizing an API, and for this objective, we’ll want API credentials. After profitable consumer creation, you’ll be capable of fetch its Entry key ID and secret entry key. You wish to seize these, and we’ll make use of them within the subsequent part associated to Subsequent JS.

Consumer credentials

Phew, we have now the least intersting work carried out (I’m sorry AWS admins, it’s simply my private opinion). Now we will reply the query about how we will add recordsdata utilizing a frontend framework.

Firstly, it’s vital that it’s going to not all be frontend. Since we will’t actually have atmosphere variables on the frontend (as a result of it’s all compiled into Javascript code, and on the finish of the day all can be seen within the browser), we’ll elevate NextJS API routes. That’s mainly a serverless resolution that’s easy and intuitive to make use of.

So how will we strategy this drawback? We’ll create an API route, which is able to create signedUrl for us, to which we then gonna make a PUT request passing the file; we wish to add as a physique. If it sounds difficult simply undergo the code, it would have rather more sense in a minute.

1. Putting in NextJS together with Tailwind CSS and Typescript

I don’t learn about you, however my most well-liked means of working with NextJS is to do it with Typescript and Tailwind CSS. Typescript offers me kind checks, and tailwind permits me to write down CSS super-fast, nearly like on the steroids. To avoid wasting your self a trouble in setting it up, here’s a template with preconfigured Typescript and Tailwind which you need to use:

2. Set up mandatory libraries

For this to work we simply want two libraries:

  • axios: which permit us to make HTTP requests,
  • aws-sdk: which permit us to utilize AWS companies
Set up of wanted libraries with yarn

3. Create file enter

The next code creates only a easy enter of kind file, which permit us to fetch a file we’ve inputted in.

Code for creating easy HTML enter

In case you’re doing it for the primary time, that is how the file data is saved inside a javascript.

Enter kind file output data

Let’s simply retailer it in useState.

File useState hook

4. Retailer your API keys from an AWS in .env.native file

Bear in mind as I informed you that there’s no actually one thing like protected saved environmental variables in frontend? I’ve meant that. However since Subsequent JS API is serverless and it’s our backend we will safely make use of them right here. Any environmental variables which aren’t prefixed with NEXT_PUBLIC_ gained’t be uncovered to the browser. In .env.native file create three variables ACCESS_KEY, SECRET_KEY, and bucket identify:

5. Arrange an S3 occasion and config properties

First issues first. You need to import S3 and create a brand new occasion of it. As you’ll be able to see properties are fairly self-explanatory, you need to specify a area, cross an entry key and secret key, and signature model which we’ll set to v4. In NextJS if you want to specify any totally different than default body-parsing properties you are able to do it within the config variable which you need to export. We’re setting a most uploaded file measurement to 8mb.

Creating an S3 occasion and exporting a config

6. Create an API route logic

First, we exclude some other HTTP methodology than POST, then we create file params wanted for s3 to generate a signedUrl for us. As you’ll be able to see there are some choices wanted. Within the POST physique, we ship a reputation and the kind of file, which we wish to add. We additionally set the “expires” time to 600 seconds, and ACL for the “public-read” which is able to make this asset publicly accessible.

API endpoint configuration

7. Importing a File to AWS S3 bucket

Protip: if you happen to’ve added your .env variables after beginning up an app with yarn dev, keep in mind to restart it, as a result of env variables are fetched firstly of an utility.

Importing a file and utilizing a beforehand created API endpoint

We first make use of the beforehand created uploadFile endpoint, to which we ship the identify and kind of a picked file. Then we fetch the URL which is able to permit us to add a file to the AWS. The URL seems like within the screenshot under. Afterward, we ship a PUT request with the file to the acquired URL.

Instance of signed URL which we acquired from the API endpoint

Within the URL the half until “.com/” is your bucket URL. You may copy it and retailer it someplace if you wish to entry it later.

8. See the uploaded file in your bucket

Now you need to see your freshly added file within the bucket. We’re carried out right here.

Efficiently uploaded file within the bucket

If you want to show a picture within the HTML you are able to do it like that

Displaying saved picture

On this article, you’ve discovered easy methods to create an AWS account, and easy methods to create an S3 bucket together with IAM customers. Now you’re additionally able to NextJS app creation which is able to present the performance of importing recordsdata to your bucket, and displaying outcomes.

If you wish to seize a code, it’s accessible right here:

More Posts