So to use IBExpert with a 64-bit Firebird version, you will need to use the Firebird 32-bit client library. Simply download a 32-bit Firebird version, for example, Firebird 2.5 32-bit ZIP version, extract the 32-bit fbclient.dll from the archive and replace the 64-bit fbclient.dll. Ibexpert 64 bit download - X 64-bit Download - x64-bit download - freeware, shareware and software downloads.
Firebird 64-bit is a relational database offering many ANSI SQL standard features that runs on Linux, Windows, and a variety of Unix platforms. Firebird offers excellent concurrency, high performance, and powerful language support for stored procedures and triggers. 
It has been used in production systems, under a variety of names, since 1981.
The Firebird Project is a commercially independent project of C and C++ programmers, technical advisors and supporters developing and enhancing a multi-platform relational based on the source code released by Inprise Corp (now known as Borland Software Corp) on 25 July, 2000. Download Firebird Offline Installer Setup 64bit for Windows Anyone can build a custom version of Firebird 64-bit, as long as the modifications are made available, under the same IDPL licensing, for others to use and build on. No fees for download, registration, licensing or deployment, even you distribute Firebird as part of your commercial software package. Firebird Features: • Support of all major platforms and operation systems • Multi-generation architecture • Powerful and developer-friendly SQL language • Logging and monitoring • Windows Trusted Authentication • Developer Tools (Firebird.NET, JayBird (Java), Delphi/C++, PHP, FireRuby.) • True Open Source • Backup and restore • Full Text Search Also Available.