This powershell snippet makes a api call to url with a json body converted from csv.

rest_example.ps1

add-type @"
    using System.Net;
    using System.Security.Cryptography.X509Certificates;
    public class TrustAllCertsPolicy : ICertificatePolicy {
        public bool CheckValidationResult(
            ServicePoint srvPoint, X509Certificate certificate,
            WebRequest request, int certificateProblem) {
            return true;
        }
    }
"@
[System.Net.ServicePointManager]::CertificatePolicy = New-Object TrustAllCertsPolicy
[System.Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12

$body = Import-Csv "path\to\body.csv" | ConvertTo-Json

$headers = New-Object "System.Collections.Generic.Dictionary[[String],[String]]"
$headers.Add("Content-Type", "application/json")

$response = Invoke-RestMethod 'https://api-url.com' -Method 'POST' -Headers $headers -Body $body
$response | ConvertTo-Json