You can find the latest Forge Tools here: https://www.sinsofasolarempire.com/downloads.aspx.
Available for download are:
Galaxy Forge - Design your own galaxies. (*included in Forge Tools Bundle and seperately)
Particle Forge - Design your own particle effects. (*included in Forge Tools Bundle and seperately)
Map Converter - Created by Ross Placing. Converters one map version to another. Defaults to converting version 2 to version 3.
Developer Exe - Debugmenu, error reporting, asserts and more for both Sins 1.15 and Entrenchment 1.01 (with some new capabilities). (*included in Forge Tools Bundle)
ConvertData - Convert between binary and text or vice versa for both Sins 1.15 and Entrenchment 1.01. (*included in Forge Tools Bundle)
ConvertXSI - Convert XSI files to the Iron Engine Mesh format. (*included in Forge Tools Bundle)
Reference Data - Text versions of all the Mesh and GameInfo for both Sins 1.15 and Entrenchment 1.01. (*included in Forge Tools Bundle)
Documentation - The original Sins modding docs. (*included in Forge Tools Bundle)