List of OSS or free STEP programs

Express Schemas

SC4 Express Archive - for STEP AP schemas that are International Standards (IS)

STEPmod on Sourceforge - for versions of modular STEP AP schemas that are in development

Express Engine - used to validate models with schemas. Old website is here

Open Source BIM Collective

JSDAI, similar to STEPcode but written in Java. Created by LKSoftWare GmbH.

STEP-toybox

Express for Free, also here

SEBNF2Pars - Creates Part 21 parsers from an EBNF representation

lgtstep - a Logtalk STEP implementation

Scripting Applications for STEP Part 21 files - uses Prolog

http://github.com/mvaerle/python-ifc

http://www.ifcgears.com/extender.php

expfront - free on-line EXPRESS schema checker

IDA-STEP Viewer - free downloadable STEP file viewer

Jen-X p28 schema generator and p21-p28 mediators - for shipbuilding STEP AP’s

OntoSTEP Protégé plugin

Reeper

STEP File Analyzer