What is the STF file format?
.stf files are Microsoft ACME Setup Table Files - the primary configuration tables for ACMSETUP.EXE, Microsoft's internal installer technology used through the mid-1990s.
The file is a plain ASCII, tab-delimited table whose rows define every step of an installation: copying files, writing registry keys, displaying dialog boxes, and branching on user choices. ACMSETUP.EXE reads the .stf alongside two companion files - SETUP.TDF (binary table data) and SETUP.INI (session configuration). Without the full set and the executable, an .stf file cannot be run.
ACME Setup shipped with Microsoft Office 4.x, Office 95, Office 97, and Visual Studio 6.0. Windows Installer (.msi) replaced it starting with Office 2000, and ACME Setup was retired around 1999. Finding an .stf file today almost always means encountering legacy installation media from that era.
The .stf is plain text and can be opened in any text editor or spreadsheet application, but no modern installer reads it programmatically. It is a pure historical artifact with no active use case.
Security & safety
RISK: LOWSTF files are plain text data files - no executable code in the STF itself. The danger would be running the accompanying ACMSETUP.EXE from an untrusted source, not the STF. Legacy ACME Setup executables from unofficial sources should be treated with caution.
Format details
in a nutshellPrograms that open STF files
Windows3 apps
Microsoft Notepad / Notepad++
Open-source Open the STF file in any text editor to read the tab-delimited contents. No execution possible without ACMSETUP.EXE.
Microsoft Excel / LibreOffice Calc
Open-source File > Open, set delimiter to Tab - displays the table structure in rows and columns for analysis.
Microsoft Office (ACME Setup)
Paid Modern Microsoft Office (2000+) does not use or recognise STF files. Listing is incorrect - remove. Technical details
deep spec| Encoding | ASCII plain text |
| Delimiter | Tab-separated columns |
| Container | None (plain text file) |
| Typical size | 50 KB - 500 KB |
| Row structure | Tree of setup actions: copy file, write registry key, show dialog, branch on condition |
| Required companion files | SETUP.TDF (binary data) and SETUP.INI (configuration) |
| Runtime engine | ACMSETUP.EXE |
| Associated OS | Windows 3.x, Windows 95, Windows 98, Windows NT 4.0 |
| Products using it | Microsoft Office 4.x, Office 95, Office 97, Visual Studio 6.0 |
| Superseded by | Windows Installer (.msi) from Office 2000 onward |
| Released | 1993-1994 (Microsoft ACME Setup, used with early Microsoft Office for Windows) |
| Latest version | N/A (format tied to ACME Setup, which was retired with Office 2000 in 1999) |
| Specification | learn.microsoft.com |
Community Q&A
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