M
API Matrix

Postmon API

⭐ Beginner's Pick Tracking / No Auth Required Beginner HTTP
Free to Use Varies (check documentation)
82 Score
Grade A
Visit Official Site Compare Alternatives

Overview

Postmon is a free, open-source API for looking up Brazilian ZIP codes (CEP) and getting structured address information. Simply provide a ZIP code and receive the street name, neighborhood, city, and state — no API key required. It also supports package tracking for select Brazilian carriers.

💡

Beginner Tip

Postmon returns HTTP 404 when a ZIP code is not found instead of an error message in the body, so check the HTTP status code first in your error handling rather than parsing the response body.

Available Data

IP address information
geographic location
ASN and ISP data

Example Response

JSON Response 
{
  "status": "success",
  "data": {
    "result": "Data from Postmon",
    "description": "An API to query Brazilian ZIP codes and orders easily, quickly and free",
    "timestamp": "2025-01-15T10:00:00Z"
  }
}

Field Reference

cep The queried ZIP code in 00000-000 format
logradouro Street name or address line for this ZIP code area
bairro Neighborhood or district name
cidade City name where this ZIP code is located
estado Brazilian state abbreviation (e.g., "SP", "RJ", "MG")
estado_info Additional state details including full name and area code

Implementation Example 

const url = "http://postmon.com.br/";
const response = await fetch(url);
if (!response.ok) throw new Error(`Request failed: ${response.status}`);
const data = await response.json();
console.log(data);

What Can You Build?

Note: These code examples are AI-generated and unverified. Always refer to the official API documentation for accurate usage.

Common Errors & Troubleshooting

404 Not Found The ZIP code (CEP) does not exist or is not in the Postmon database
✓ Validate the CEP is 8 digits and try with and without the hyphen; some CEPs may only appear in ViaCEP or Correios databases
Connection refused or timeout Postmon is a community-maintained service with occasional downtime
✓ Implement a fallback to ViaCEP (https://viacep.com.br) as a secondary provider for production applications
Missing address fields in response Some CEPs (particularly PO boxes or large receivers) only have partial address data
✓ Always check for field existence before accessing; use default values for missing fields like logradouro or bairro

Matrix Score Breakdown

🌐 Reachability 30/30
⚡ Speed 20/20
🔒 Security 5/15
🛠 Developer XP 20/20
✓ Reliability 7/15
Response Time 31ms

Fully tested on Apr 5, 2026

Technical Specifications

Auth No Auth
HTTPS NO
CORS UNKNOWN
Category Tracking
Difficulty Beginner
Verified: 2026-04-04

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