The latest articles on DEV Community by Daniel Freitas (@daniel_freitas_6b99d8e91b). https://dev.to/daniel_freitas_6b99d8e91b https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.us-east-2.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F2568021%2F33665614-e4e9-48a4-ba30-d935f3a59a6d.jpg https://dev.to/daniel_freitas_6b99d8e91b en Daniel Freitas Thu, 18 Jun 2026 20:56:39 +0000 https://dev.to/daniel_freitas_6b99d8e91b/i-built-cepify-a-free-brazilian-postal-code-cep-api-viacep-compatible-spring-boot-4-java-25-5hl9 https://dev.to/daniel_freitas_6b99d8e91b/i-built-cepify-a-free-brazilian-postal-code-cep-api-viacep-compatible-spring-boot-4-java-25-5hl9 <p>Quick context for non-Brazilian readers: a <strong>CEP</strong> (<em>Código de Endereçamento Postal</em>) is Brazil's equivalent<br> of a ZIP/postal code. The de-facto free API for it is <a href="https://viacep.com.br" rel="noopener noreferrer">ViaCEP</a>, which is great — but<br> I wanted a project to really dig into <strong>Spring Boot 4 + Java 25</strong>, and I kept wanting something I fully<br> control. So I built <strong>Cepify</strong>, a free, high-performance CEP lookup web service.</p> <p>🔗 <a href="https://cepify.com.br" rel="noopener noreferrer">https://cepify.com.br</a></p> <h2> What it does </h2> <ul> <li>CEP lookup returning <strong>JSON, XML and JSONP</strong> </li> <li> <strong>Address search</strong> (state / city / street)</li> <li> <strong>ViaCEP compatibility</strong>: it mirrors ViaCEP's routes and response shape (including the classic <code>{"erro": "true"}</code> for a missing CEP), so you can switch the base URL on existing ViaCEP code</li> <li>A "proper" REST API too (<code>/v1/ceps/{cep}</code>) with <code>ETag</code> / <code>Cache-Control</code> and standardized errors</li> <li> <strong>No sign-up, no API key</strong>, with per-IP rate limiting</li> </ul> <h2> A few technical decisions I found interesting </h2> <ul> <li>The database holds <strong>~1.5M postal codes</strong>, loaded by an ETL that processes the Brazilian Post Office's <strong>e-DNE</strong> dataset. Keeping it fresh without taking the production table down was honest work.</li> <li> <strong>Caffeine cache</strong> in front of lookups (the service is far more read than write) — made responses snappy.</li> <li> <strong>Observability via logs, not a table</strong>: every request becomes a JSON access-log line + Prometheus metrics. For a read-heavy service (and with privacy/LGPD in mind) that felt healthier than writing everything to the DB.</li> <li>Docs via <strong>Swagger/OpenAPI</strong>.</li> </ul> <p>Stack: Spring Boot 4, Java 25, PostgreSQL, Caffeine, Flyway, behind Cloudflare.</p> <h2> About </h2> <p>It's a <strong>personal, free project</strong> — no enterprise SLA, but it's live and working. I'd genuinely love<br> feedback, especially: <strong>what would you want from a postal-code API that existing ones don't offer today?</strong></p> api java showdev springboot