Response Headers

Every API response includes these headers:

Header	Type	Description
x-cost	integer	Credits deducted from your wallet for this request
x-balance	integer	Credits remaining in your wallet after this request

Note

x-balance is the most efficient way to monitor your balance — it’s included on every response at no extra cost, so you don’t need to call the balance endpoint separately.

Reading Headers

cURL

# Use -i to show response headers
curl -i 'https://api.echovalue.dev/kv/default/mykey' \
  -H 'x-token: mytoken'

# Output includes:
# x-cost: 1
# x-balance: 99

JavaScript

fetch('https://api.echovalue.dev/kv/default/mykey', {
  headers: { 'x-token': 'mytoken' }
})
.then(response => {
  console.log('Cost:', response.headers.get('x-cost'));
  console.log('Balance:', response.headers.get('x-balance'));
  return response.text();
});

Python

import requests

response = requests.get('https://api.echovalue.dev/kv/default/mykey',
  headers={'x-token': 'mytoken'}
)
print('Cost:', response.headers.get('x-cost'))
print('Balance:', response.headers.get('x-balance'))

PHP

<?php
$ch = curl_init('https://api.echovalue.dev/kv/default/mykey');
curl_setopt($ch, CURLOPT_HTTPHEADER, ['x-token: mytoken']);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HEADER, true);

$response = curl_exec($ch);
$headerSize = curl_getinfo($ch, CURLINFO_HEADER_SIZE);
$headers = substr($response, 0, $headerSize);
curl_close($ch);

// Parse x-balance from headers
preg_match('/x-balance:\s*(\d+)/i', $headers, $matches);
echo 'Balance: ' . $matches[1];
?>

Go

package main

import (
    "fmt"
    "net/http"
)

func main() {
    req, _ := http.NewRequest("GET", "https://api.echovalue.dev/kv/default/mykey", nil)
    req.Header.Set("x-token", "mytoken")

    client := &http.Client{}
    resp, _ := client.Do(req)
    defer resp.Body.Close()

    fmt.Println("Cost:", resp.Header.Get("x-cost"))
    fmt.Println("Balance:", resp.Header.Get("x-balance"))
}