What is the FOL file format?
.fol is a database file associated with PFS:First Choice, an integrated office suite developed by Software Publishing Corporation (SPC) for MS-DOS and early Windows systems. FOL files store flat-file databases that supported basic queries, data entry forms, and report generation - the database component of the First Choice application suite.
The format uses a proprietary binary record structure with fixed-length fields. The field schema (names and types) is stored in the file's own header area alongside the data records. Unlike the contemporary .DBF format used by dBASE and Clipper, FOL files are single-table flat-file stores tied exclusively to the First Choice application.
The .fol format is considered obsolete and is no longer supported by any current database management software. PFS:First Choice was discontinued in the early 1990s and is now abandonware. The software can still be run via DOSBox to open original FOL files directly. Free converter utilities - notably first2html (available on SourceForge) and FirstOut - can extract and convert FOL data to more accessible modern formats such as CSV.
Note that .fol is also used for Windows Mail folder configuration files - an entirely separate format that happens to share the same extension.
Security & safety
RISK: LOWFOL files are legacy data files with no executable capability. The only risk is data loss due to format obsolescence - always make a copy before attempting conversion.
Format details
in a nutshell- Microsoft Windows Mail Folder File - Windows Mail (Vista/7 era) saves user mailbox folder settings/layout in a .fol file; unrelated binary format.
- FirstOut Conversion Output - Some sources list .fol as output of the FirstOut DOS utility - same PFS format family.
Programs that open FOL files
Windows2 apps
DOSBox
Open-source Mount the directory containing the FOL file, then run the original PFS:First Choice DOS executable inside DOSBox to open the database. 
first2html
Open-source Command-line converter: 'first2html database.fol > output.html' extracts the database as an HTML table. Technical details
deep spec| Encoding | Binary/text mixed - fixed-width text fields within a proprietary binary record structure |
| Byte order | Little-endian |
| Container | Proprietary flat-file; schema (field names and types) stored in the file header alongside data records |
| Record structure | Fixed-length records; all field definitions and data reside in the single .fol file (no separate schema file) |
| Database type | Single-table flat-file; no joins, no indexes, no relational query support |
| Compression | None - uncompressed flat-file format |
| Typical file size | 10 KB - 10 MB (typical DOS-era database file) |
| File signature | No publicly documented magic bytes; no standard header identifier - identified by context and DOS-era file provenance |
| MIME type | application/octet-stream (no registered MIME type) |
| Developer | Software Publishing Corporation (SPC) - not SoftKey International, which later distributed consumer software bundles |
| Version differences | Format evolved across PFS:First Choice 1.x, 2.x, and 3.0 (early 1990s); version differences are undocumented |
| Associated OS | MS-DOS; Windows legacy environments via DOSBox emulation |
| Data recovery tools | first2html and FirstOut utilities convert FOL files to HTML or CSV without requiring the original First Choice application |
| Released | circa 1985, with PFS:First Choice for MS-DOS |
| Latest version | PFS:First Choice 3.0 (early 1990s) - abandonware, no further versions |
FOL conversions
Community Q&A
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