Port 1527 is the default network server port for Apache Derby, a pure-Java relational database management system. When you connect to a Derby database running as a network service, you're almost certainly connecting through port 1527—unless someone explicitly changed it.
What Runs on This Port
Apache Derby Network Server listens on TCP port 1527 by default. Derby is a relational database written entirely in Java, small enough to embed in applications but capable of running as a client-server database for multiple connections.1
A typical JDBC connection URL looks like this:
The database server listens. Client applications connect. SQL queries flow back and forth. It's the standard client-server pattern, just happening on port 1527 instead of the more famous database ports like 3306 (MySQL) or 5432 (PostgreSQL).
The Story: From Cloudscape to Apache to Retirement
Port 1527's history is tied to a database that changed hands four times before finding its final home at Apache.
The Cloudscape Era (1996-1999)
In 1996, two engineers named Nat Wyatt and Howard Torf founded Cloudscape Inc. in Oakland, California with one goal: build a database management system entirely in Java.2
This was ambitious. Java was barely a year old. The idea of a pure-Java database—no native code, no platform dependencies, just bytecode—was novel enough to be interesting and risky enough to be worth trying.
Their first release in 1997 was called JBMS (Java-Based Management System). It worked. They renamed it Cloudscape and kept shipping releases every six months.
The Informix Years (1999-2001)
In 1999, Informix Software acquired Cloudscape Inc. and the database along with it. Two years later, IBM acquired Informix's database assets, including Cloudscape.
IBM rebranded it as IBM Cloudscape and used it internally. But in 2004, they did something unexpected: they contributed the entire codebase to the Apache Software Foundation.3
Apache Derby (2004-2025)
The Apache incubator accepted the donation in August 2004 and named it Derby. The database graduated from incubation in July 2005 and became an official Apache project.
Then Sun Microsystems noticed. They needed a lightweight database to ship with the Java Development Kit. Derby was pure Java, open source, and Apache-licensed. Perfect.
In December 2006, when Java 6 launched, Derby was inside it—rebranded as "Java DB."4 For nearly a decade, every developer who downloaded the JDK got Apache Derby bundled in. Most didn't know it was there. The ones who did found it useful for development, testing, and embedded applications that needed a real SQL database without the weight of a full server install.
When Oracle acquired Sun Microsystems in 2010, they kept shipping Java DB. But in June 2015, Oracle announced they would stop bundling it starting with JDK 9.5
Derby kept going as an Apache project. But on October 10, 2025, the Derby developers voted to retire the project into a read-only state. Development stopped. Bug-fixing ended. No further releases.2
Port 1527 became a monument.
Why Port 1527?
The port number itself has an odd footnote. The IANA registry lists port 1527 as officially assigned to Oracle for a service called "tlisrv."6 But that's not what port 1527 became famous for. Apache Derby claimed it as a de facto standard, and for twenty years, that's what mattered.
Derby's documentation simply states: "By default, the Network Server listens on TCP/IP port number 1527."7 If you wanted a different port, you could specify it on the command line. Most people didn't bother.
How Derby Network Server Works
Derby can run in two modes:
- Embedded mode — The database runs inside the same JVM as the application. No network, no port, just direct access to database files.
- Client-server mode — The database runs as a network service. Applications connect remotely via JDBC. This is where port 1527 matters.
When you start the Derby Network Server, it binds to port 1527 and listens for incoming connections. Multiple applications—running in different JVMs, possibly on different machines—can connect simultaneously.
Each connection speaks the Derby client protocol over TCP. The server processes SQL queries, manages transactions, enforces ACID guarantees, and sends results back to the client.8
It's a straightforward architecture. Derby wasn't trying to compete with Oracle Database or PostgreSQL on performance or features. It was trying to be simple, embeddable, and pure Java. For that use case, it succeeded.
What Made Derby Matter
Derby was never the fastest database. It wasn't the most feature-rich. But it had qualities that made it valuable for specific use cases:
- Pure Java — No native libraries, no platform dependencies. If you could run a JVM, you could run Derby.
- Small footprint — The entire database engine was about 2.6 MB. You could embed it in desktop applications or mobile devices.
- Zero administration — In embedded mode, there was no server to configure, no daemon to manage. Just add the JAR to your classpath and start writing SQL.
- Apache license — Open source and permissively licensed. Companies could use it, modify it, ship it in commercial products without worrying about GPL restrictions.
For developers building Java applications that needed a real SQL database without the overhead of installing and managing a separate database server, Derby was often the answer.
Security Considerations
Derby's Network Server on port 1527 requires authentication by default, but the security model is simpler than enterprise databases. A few things to keep in mind:
- Authentication is required — Clients must provide a username and password. But Derby's built-in authentication is basic. For production use, you'd integrate with LDAP or another external authentication system.9
- No encryption by default — Network traffic between client and server is unencrypted unless you explicitly configure SSL. Credentials and data travel in plaintext over port 1527 unless you protect it at the network level or enable Derby's SSL support.
- Firewall exposure — If port 1527 is exposed to the Internet (which it shouldn't be), an attacker can attempt to connect. Derby's authentication will stop unauthorized access, but unencrypted traffic is still visible to anyone sniffing packets.
- Deprecated and unmaintained — As of October 2025, Derby is no longer actively developed. No new security patches will be released. If you're still running Derby in production, you should plan a migration.
Derby was designed for development and embedded use cases, not high-security production environments. Treat it accordingly.
Checking What's Listening on Port 1527
If you want to see if Derby (or anything else) is listening on port 1527:
On Linux/Mac:
On Windows:
If Derby Network Server is running, you'll see a process bound to port 1527.
To test connectivity:
If the port is open, telnet will connect (though you won't be able to do much without speaking the Derby client protocol).
Related Ports
- Port 1521 — Oracle Database's default listener port. Often confused with 1527 because both are Oracle-related, but they serve completely different databases.
- Port 3306 — MySQL's default port.
- Port 5432 — PostgreSQL's default port.
- Port 50000 — IBM DB2's default port.
Derby was the lightweight alternative to these enterprise databases—simpler, smaller, embeddable.
The End of an Era
On October 10, 2025, the Apache Derby project retired. The developers voted to move the project into a read-only state. The mailing lists went quiet. The bug tracker froze. The final release, whatever it was, became the last release.2
This doesn't mean Derby disappeared overnight. Code that runs on Derby still runs. Databases that rely on port 1527 still work. But there's no one maintaining it anymore. No security patches. No bug fixes. No new features.
For two decades, port 1527 was the sound of Java applications talking to a database that shipped with the JDK. Now it's an artifact—a port number that still works but points to a project that's done.
Derby served its purpose. It was small, simple, and pure Java. It ran embedded in applications and as a network service. It gave developers a SQL database they could bundle without complications. And when its time was over, it stepped aside gracefully.
Port 1527 is a reminder that not every piece of infrastructure lasts forever. Sometimes the best thing a project can do is serve its era well and then retire.
Frequently Asked Questions About Port 1527
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