dotnet add package AWSSDK.S3 --version 3.3.110.19

PM> Install-Package AWSSDK.S3

PM> Install-Package AWSSDK.S3 -Version 3.3.106.6

using System;
using Amazon;
using Amazon.S3;
using Amazon.S3.Util;
using Amazon.S3.Model;
using Amazon.S3.Transfer;
using System.Threading.Tasks;

public class MyS3Service
{
    private readonly IAmazonS3 s3Client;
    public MyS3Service()
    {
        s3Client = new AmazonS3Client(
             "Your Aws Access Key Id here",
             "Your Aws Secret Access Key here",
             RegionEndpoint.GetBySystemName("Your Region Name here"));
    }
}

public async Task CreateNewBucketAsync()
{
    try
    {
        // to check if there is another bucket with the same name
        // make sure to use V2 of the function because V1 is obsolete
        if (!(await AmazonS3Util.DoesS3BucketExistV2Async(s3Client, "Your New Bucket Name Here")))
        {
            var putBucketRequest = new PutBucketRequest
            {
                BucketName = "Your New Bucket Name Here",
                UseClientRegion = true
            };
            PutBucketResponse putBucketResponse = await s3Client.PutBucketAsync(putBucketRequest);
        }
    }
    catch (AmazonS3Exception e)
    {
        Console.WriteLine("Error encountered on server. Message:'{0}' when writing an object", e.Message);
    }
    catch (Exception e)
    {
        Console.WriteLine("Unknown encountered on server. Message:'{0}' when writing an object", e.Message);
    }
}

public async Task UploadObjectAsync()
{
    try
    {
        // Method 1. Put object-specify only key name for the new object.
        var putRequest1 = new PutObjectRequest
        {
            BucketName = "Your Bucket Name Here",
            Key = "Unique identifier for the object",
            ContentBody = "sample text"
        };

        PutObjectResponse response1 = await s3Client.PutObjectAsync(putRequest1);

        //______________________________________________________________________

        //Method  2. Put the object-set ContentType and add metadata.
        var putRequest2 = new PutObjectRequest
        {
            BucketName = "Your Bucket Name Here",
            Key = "Unique identifier for the object",
            FilePath = "File path goes here",
            ContentType = "text/plain"
        };

        putRequest2.Metadata.Add("x-amz-meta-title", "someTitle");
        PutObjectResponse response2 = await s3Client.PutObjectAsync(putRequest2);
    }
    catch (AmazonS3Exception e)
    {
        Console.WriteLine(
                "Error encountered ***. Message:'{0}' when writing an object"
                , e.Message);
    }
    catch (Exception e)
    {
        Console.WriteLine(
            "Unknown encountered on server. Message:'{0}' when writing an object"
            , e.Message);
    }
}

public async Task UploadFileAsync()
{
    try
    {
        var yourBucketName = "TestBucket";
        var yourFilepath = "Your File path";
        var yourfileKey = "Your Unique Key here";

        var fileTransferUtility =new TransferUtility(s3Client);

        // Option 1. Upload a file. The file name is used as the object key name.
        await fileTransferUtility.UploadAsync(yourFilepath, yourBucketName);
        Console.WriteLine("Upload 1 completed");

        //______________________________________________________________________

        // Option 2. Specify object key name explicitly.
        await fileTransferUtility.UploadAsync(yourFilepath, yourBucketName, yourfileKey);
        Console.WriteLine("Upload 2 completed");

        //______________________________________________________________________

        // Option 3. Upload data from a type of System.IO.Stream.
        using (var fileToUpload =new FileStream(yourFilepath, FileMode.Open, FileAccess.Read))
        {
            await fileTransferUtility.UploadAsync(fileToUpload, yourBucketName, yourfileKey);
        }
        Console.WriteLine("Upload 3 completed");

        //______________________________________________________________________
        // Option 4. Specify advanced settings.
        var fileTransferUtilityRequest = new TransferUtilityUploadRequest
        {
            BucketName = yourBucketName,
            FilePath = yourFilepath,
            StorageClass = S3StorageClass.StandardInfrequentAccess,
            PartSize = 6291456, // 6 MB.
            Key = yourfileKey,
            CannedACL = S3CannedACL.PublicRead // to determine Access control list to file
        };

        //if you need to add metadata to your files
        fileTransferUtilityRequest.Metadata.Add("param1", "Value1");
        fileTransferUtilityRequest.Metadata.Add("param2", "Value2");

        await fileTransferUtility.UploadAsync(fileTransferUtilityRequest);
        Console.WriteLine("Upload 4 completed");
    }
    catch (AmazonS3Exception e)
    {
        Console.WriteLine("Error encountered on server. Message:'{0}' when writing an object", e.Message);
    }
    catch (Exception e)
    {
        Console.WriteLine("Unknown encountered on server. Message:'{0}' when writing an object", e.Message);
    }
}

public async Task ReadObjectDataAsync()
{
    var yourBucketName = "TestBucket";
    var yourfileKey = "Your Unique Key here";
    string responseBody = "";
    try
    {
        GetObjectRequest request = new GetObjectRequest
        {
            BucketName = yourBucketName,
            Key = yourfileKey
        };
        using (GetObjectResponse response = await s3Client.GetObjectAsync(request))
        using (Stream responseStream = response.ResponseStream)
        using (StreamReader reader = new StreamReader(responseStream))
        {
            string title = response.Metadata["x-amz-meta-title"]; // Assume you have "title" as medata added to the object.
            string contentType = response.Headers["Content-Type"];
            Console.WriteLine("Object metadata, Title: {0}", title);
            Console.WriteLine("Content type: {0}", contentType);
            responseBody = reader.ReadToEnd(); // Now you process the response body.
        }
    }
    catch (AmazonS3Exception e)
    {
        // If bucket or object does not exist
        Console.WriteLine("Error encountered ***. Message:'{0}' when reading object", e.Message);
    }
    catch (Exception e)
    {
        Console.WriteLine("Unknown encountered on server. Message:'{0}' when reading object", e.Message);
    }
}

public async Task DeleteObject()
{
    try
    {
        var yourBucketName = "TestBucket";
        var yourfileKey = "Your Unique Key here";
        var deleteObjectRequest = new DeleteObjectRequest
        {
            BucketName = yourBucketName,
            Key = yourfileKey
        };

        Console.WriteLine("Deleting an object");
        await s3Client.DeleteObjectAsync(deleteObjectRequest);
    }
    catch (AmazonS3Exception e)
    {
        Console.WriteLine("Error encountered on server. Message:'{0}' when deleting an object", e.Message);
    }
    catch (Exception e)
    {
        Console.WriteLine("Unknown encountered on server. Message:'{0}' when deleting an object", e.Message);
    }
}

public async Task GetObjectsList()
{
    try
    {
        ListVersionsRequest request = new ListVersionsRequest()
        {
            BucketName = "Your Bucket Name",
            // You can optionally specify key name prefix in the request
            // if you want list of object versions of a specific object.

            // For this example we limit response to return list of 2 versions.
            MaxKeys = 2
        };
        do
        {
            ListVersionsResponse response = await s3Client.ListVersionsAsync(request);
            // Process response.
            foreach (S3ObjectVersion entry in response.Versions)
            {
                Console.WriteLine("key = {0} size = {1}",entry.Key, entry.Size);
            }

            // If response is truncated, set the marker to get the next 
            // set of keys.
            if (response.IsTruncated)
            {
                request.KeyMarker = response.NextKeyMarker;
                request.VersionIdMarker = response.NextVersionIdMarker;
            }
            else
            {
                request = null;
            }
        } while (request != null);
    }
    catch (AmazonS3Exception e)
    {
        Console.WriteLine("Error encountered on server. Message:'{0}' when writing an object", e.Message);
    }
    catch (Exception e)
    {
        Console.WriteLine("Unknown encountered on server. Message:'{0}' when writing an object", e.Message);
    }
}