Authentication

Every request to Zerion API carries one credential. Pick the one that fits how you call it:

API keyMost common Free key, plan-based rate limits. For apps with steady traffic. Authorization: Basic Pay per call in USDC on Base or Solana. Agent-friendly, no key needed. PAYMENT-SIGNATURE Pay per call in USDC on Tempo. Agent-friendly, no key needed. Authorization: Payment

All three unlock the same endpoints with the same parameters. Only the header changes.

API key

Zerion API uses HTTP Basic Authentication, with your API key as the username and an empty password. Get a key from the Dashboard; its Get Started section also has ready-to-use snippets with your key pre-filled.

1 · Key + colonYOUR_API_KEY:

→

2 · Base64-encodeWU9VUl9BUElfS0VZOg==

3 · Send as headerAuthorization: Basic WU9VUl9BUElfS0VZOg==

Username = your API key, password = empty. Keep the trailing colon: it separates the two.

Make your first call

From the docs: every API reference page has a playground. Click Try it, paste your API key in Username, leave Password empty, and click Send. From your code: most HTTP clients build the header when you pass the key as the Basic Auth username. Otherwise, encode it as shown above.

# -u builds the Basic Auth header for you (note the trailing colon)
curl "https://api.zerion.io/v1/wallets/0x42b9df65b219b3dd36ff330a4dd8f327a6ada990/portfolio" \
  -u "YOUR_API_KEY:" \
  -H "accept: application/json"

// Transform your API key for Basic Auth
const apiKey = 'YOUR_API_KEY';
const apiKeyTransformed = btoa(apiKey + ':');

// Make the request
const response = await fetch(
  'https://api.zerion.io/v1/wallets/0x42b9df65b219b3dd36ff330a4dd8f327a6ada990/portfolio',
  {
    headers: {
      'Authorization': `Basic ${apiKeyTransformed}`,
      'accept': 'application/json'
    }
  }
);
const data = await response.json();
console.log(data);

import requests
import base64

# Transform your API key for Basic Auth
api_key = 'YOUR_API_KEY'
api_key_transformed = base64.b64encode(f'{api_key}:'.encode()).decode()

# Make the request
response = requests.get(
    'https://api.zerion.io/v1/wallets/0x42b9df65b219b3dd36ff330a4dd8f327a6ada990/portfolio',
    headers={
        'Authorization': f'Basic {api_key_transformed}',
        'accept': 'application/json'
    }
)
data = response.json()
print(data)

import (
    "encoding/base64"
    "net/http"
)

// Transform your API key for Basic Auth
apiKey := "YOUR_API_KEY"
apiKeyTransformed := base64.StdEncoding.EncodeToString([]byte(apiKey + ":"))

// Make the request
client := &http.Client{}
req, _ := http.NewRequest("GET", "https://api.zerion.io/v1/wallets/0x42b9df65b219b3dd36ff330a4dd8f327a6ada990/portfolio", nil)
req.Header.Set("Authorization", "Basic " + apiKeyTransformed)
req.Header.Set("accept", "application/json")

resp, _ := client.Do(req)
defer resp.Body.Close()

Security best practices

Never expose your API key in client-side code or public repositories.

Store your API key in environment variables
Make API requests from server-side code
Rotate your key immediately if it’s ever compromised
Use separate keys for development and production

Pay-per-request: x402 and MPP

Both x402 and MPP let you call Zerion API by paying a small USDC fee per request instead of presenting an API key. They’re a better fit than API keys when:

You’re building an AI agent or automated pipeline that shouldn’t manage long-lived credentials
Traffic is bursty or unpredictable and you don’t want to size a rate-limited plan
You want usage-based cost accounting at the request level

Pick whichever chain your wallet already holds USDC on, then follow the x402 guide or the MPP guide. The Zerion CLI supports both via --x402 / --mpp flags.

Get started

Core concepts

Migrating to Zerion API

API key

Make your first call

Security best practices

Pay-per-request: x402 and MPP

​API key

​Make your first call

​Security best practices

​Pay-per-request: x402 and MPP

API key

Make your first call

Security best practices

Pay-per-request: x402 and MPP